US3327311A - Extensible dipole with adjustable loading coils - Google Patents

Extensible dipole with adjustable loading coils Download PDF

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Publication number
US3327311A
US3327311A US379817A US37981764A US3327311A US 3327311 A US3327311 A US 3327311A US 379817 A US379817 A US 379817A US 37981764 A US37981764 A US 37981764A US 3327311 A US3327311 A US 3327311A
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antenna
contact
coil
sleeve
band
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US379817A
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Altmeyer John
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NEW TRONICS Inc
NEW-TRONICS Inc
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NEW TRONICS Inc
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q9/00—Electrically-short antennas having dimensions not more than twice the operating wavelength and consisting of conductive active radiating elements
    • H01Q9/04—Resonant antennas
    • H01Q9/06—Details
    • H01Q9/14—Length of element or elements adjustable

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  • This invention pertains to the art of radio antennas and more particularly to a radio antenna which may be remotely switched from one desired frequency band of operation to another.
  • the present invention is particularly applicable to a radio antenna of the type generally referred to as a dipole which is electrically energized at a point intermediate its ends, and will be described with particular reference thereto, although it will be appreciated that the invention has broader applications and may be used, for example, with end-fed quarter wave antennas.
  • the present invention deals with these problems of controlling the operating frequency band of an antenna and enables the operator to remotely select a desired frequency band without the requirement of physically manipulating adjustable taps on an antenna loading coil and without electrical problems. More particularly, the band switching mechanism of the present'invention provides for selectively short circuiting a portion of the loading coil with a metal shorting bar.
  • band switching means for remotely selecting the operating frequency band of an antenna which changes the inductance of an antenna loading coil with a shorting bar which is located exteriorly of the coil a sufiicient distance so as to not materially affect the magnetic field of the coil.
  • a multi-band antenna having a finite length antenna member, a resonator coil and an extendable antenna member movably secured to one end of the resonator coil.
  • a movable shorting bar is spaced from the coil a sufficient distance so as to not materially affect the magnetic field of the coil and is remotely actuated to short circuit a portion of the coil when desired to obtain band switching.
  • the primary object of the present invention is to provide means for remotely selecting the operating frequency band of an antenna which is simple in construction and economical to manufacture.
  • Another object of the present invention is to provide band switching means for varying the inductance of an antenna loading coil without materially affecting the magnetic field of the coil.
  • Another object of the present invention is to provide means for changing the operating frequency band of an antenna without resorting to the use of wave traps.
  • a still further object of the present invention is to provide an antenna having means for remote tuning of the antenna by varying the physical length of the antenna, as well as means for remotely changing the operating frequency band of the antenna.
  • a still further object of the present invention is to provide antenna band switching means exhibiting minimum are over so as to permit use with a resonator coil having voltage about the coil of relatively high power level.
  • Another object of the present invention is to provide antenna band switching means without the use of a metal shorting bar located within the interior of the resonator coil structure.
  • FIGURE 1 is a schematic elevational view illustrating the preferred embodiment of the invention
  • FIGURE 2 is an enlarged sectional view taken along line 2-2 of FIGURE 1;
  • FIGURE 3 is an enlarged fragmentary plan view of the antenna shown in FIGURE 1;
  • FIGURE 4 is an enlarged elevational view partly in section of one portion of the antenna shown in FIGURE 1;
  • FIGURE 5 is an enlarged plan view partly in section of another portion of the antenna shown in FIGURE 1;
  • FIGURE 6 is an elevational view of the portion of the antenna shown in FIGURE 5
  • FIGURE 7 is an enlarged elevational View partly in section of another portion of the antenna shown in FIG- URE 1;
  • FIGURE 8 is an enlarged sectional view of the portion of the antenna shown in FIGURE 7;
  • FIGURE 9 is a sectional view taken along line 9-9 of FIGURE 8.
  • FIGURE 10 is a schematic circuit diagram of a motor control circuit in accordance with the invention.
  • FIG. 1 there is illustrated a center fed, half wave dipole antenna 10 comprising an aluminum housing 12 having a pair of hollow coaxially aligned antenna elements 14 and 16 extending therefrom in opposing directions.
  • Antenna element 14 is of fixed length and includes an aluminum cylindrical sleeve 18, a hollow resonator coil assembly 22 and another aluminum cy indrical sleeve 26.
  • antenna element 16 is of fixed length, equal to that of element 14 and includes an aluminum cylindrical sleeve 20, a hollow resonator coil assembly 24 and another aluminum cylindrical sleeve 28.
  • Extending coaxially from antenna elements 14 and 16 are extendable aluminum antenna members 30 and 32 respectively, shown in their fully extended positions in FIGURE 1.
  • Radio frequency power is applied to the antenna 10 at spaced feed points or antenna terminals 34 and 36 from a transmitter 38 via a SWR (standing wave ratio) indicator or meter 40.
  • Any suitable feed line may be used to connect terminals 34 and 36 with the transmitter 38 although, as shown in FIGURE 1, a coaxial cable 42 is provided having a characteristic im- 0 pedance of approximately 52 ohms.
  • Each extendable antenna member 30 and 32 is connected to a reversible motor located within the housing (not shown in FIGURE 1) for purposes of varying the length of the antenna 10 to tune the antenna.
  • utilization is made of a motor control console 44 connected to the two reversible motors within the housing 12 via lead pairs 46 and 48 to control the operation of the motors.
  • the control console 44 includes a switch lever 47, selectively actuable to L and Hi positions for simultaneously energizing both motors to extend or retract the extendable antenna members 311 and 32.
  • a spring biased, normally closed, push button switch 50 is provided on the top of console 44 for purposes of deenergizing one of the reversible motors so that fine tuning of the antenna may be accomplished by extending or retracting only one of the extendable antenna members 30 and 32. Further, the console 44 is provided with an indicator lamp 52 which is operative to be energized and glow brightly only when one or both of the reversible motors in housing 12 is energized.
  • the housing 12 comprises a left half portion 13 and a right half portion 15 separated by a suitable gasket to provide a weather tight seal and electrically insulates the two housings, one from the other.
  • the housing portions 13 and 15 are secured together by any suitable means, such as nut and bolt assemblies, and rest in a cradle 17 and secured thereto by means of suitable straps 19.
  • the cradle 17 is securely mounted to the top of a post or pipe 21 in such a manner that antenna elements 14 and 16 are horizontally aligned with respect to ground level so as to thereby insure relatively constant capacitance to ground along the length of the antenna.
  • the description thus far has been particularly directed toward the general arrangement of the remotely tuned radio antenna described and claimed in my copending parent application, Ser. No. 327,713, identified hereinbefore, the description of which is incorporated herein by reference.
  • the antenna structure disclosed by that application does not provide means for remotely selecting a desired operating frequency band, but is directed toward means for remotely tuning the antenna within a particular frequency band.
  • the band selecting means includes a pair of band switch assemblies 54 and 56 respectively mounted on antenna elements 14 and 16 for purposes of changing the inductance of resonator coil assemblies 22 and 24 in order to obtain a desired operating frequency band.
  • Band switch assemblies 54 and 56 are respectively controlled by extendable and retractable shorting bars (not shown in FIGURE 1) which are encased within hollow aluminum tubes 58 and 60 respectively, extending from switch assemblies 54 and 56 to a band switch motor control housing 62.
  • the control console 44 also includes a slide switch 66 selectively actuable to provide band switching operation, as shown in the dotted position in FIGURE 1, or band tuning operation, as shown by the solid lines.
  • FIGURES 2 through 10 Since the features of both halves of the antenna 10, i.e., including the left and right half antenna elements 14 and 16 extending outwardly of housing 12 to the antenna members and 32, are the same, only the right half of antenna 10 will be described in detail. It is to be understood that the following description applies equally to the left half of the antenna 10.
  • a housing support bracket 67 is secured on the top surface of antenna housing 12 by any suitablemeans, such as bolts 68.
  • a band switch motor control housing cover 62 is removably secured to the bracket 67 as by screws 72 and defines a chamber 74 containing a reversible A.C. motor 76.
  • Motor 76 is secured within housing 62 to the bracket 67 as by bolts 78.
  • Motor 76 is provided with an output shaft 80 drivingly connected to a rack drive gear 82 via a suitable gear train 84.
  • Drive gear 82 is interposed between a pair of gear racks 86 and 88 aligned in parallel relationship with each other and together defining a plane perpendicular to the axis of rotation of drive gear 82.
  • Gear racks 86 and 88 are respectively provided with gear teeth 90 and 92 maintained in meshed gear engagement with gear teeth 94 of drive gear 82. In this manner, upon rotation of gear 82 in a given direction about its axis of rotation, gear racks 86 and 88 will be driven in opposing parallel directions.
  • gear rack 86 extend through apertures 96 and 98 of upstanding side walls 7 and 99 suitably secured to the support bracket 67 and are respectively received within coaxially aligned brass rack tubes 1% and 102.
  • rack 88 extend through apertures 104 and 106 in side walls 97 and 99 and are respectively received within 'coaxially aligned brass rack tubes 108 and 110.
  • Rack tubes and 1118 are secured to the left half portion 13 of housing 12 by means of a suitable bracket 112 so that tubes 100 and 108 are coplanar and extend in a direction parallel to antenna element 14.
  • rack tubes 1112 and are secured to the right half portion 15 of housing 12 by means of a bracket 114 so that tubes 102. and 110 are coplanar and extend in a direction parallel, to antenna element 16.
  • a brass cylindrical guide sleeve 118 is threaded to a portion of threading 116 and extends therefrom, as viewed in FIGURE 3, toward drive gear 82.
  • a cylindrical brass coupling 120 having an outer diameter equal to that of sleeve 118 is threaded to the remaining portion of threading 116 on rack 86 and includes a depending cylindrical sleeve portion 122 which extends axially to the right of threading 116.
  • the cylindrical sleeve portion 122 serves to receive a fiber glass push rod 124, as shown in FIGURE 3.
  • the sleeve portion 122 is fastened securely to push rod 124 as by staking the sleeve, to the rod which may be accomplished by utilizing a suitable tool to squeeze sleeve portion 122 radially inward into tightly gripping fashion with rod 124.
  • brass sleeve 118 is staked to gear rack 86.
  • the left end of gear rack 86 has mounted thereon a brass guide sleeve 126 which is tightly secured to the rack as by staking.
  • the outer diameters of guide sleeves 126 and 118 are of a dimension to obtain a sliding fit with the inner surfaces of rack tubes 100 and 102 respectively, whereby alignment of rack 86 is obtained throughout its movement within tubes 100 and 102.
  • gear rack 88 is also provided with guide sleeves at its opposing ends.
  • gear rack 88 is also provided with guide sleeves at its opposing ends.
  • a brass guide sleeve 127 and a brass coupling 128 which are threaded and staked on rack 88 in the same manner as sleeve 118 and coupling 121 are threaded and staked on rack 86.
  • a fiber glass push rod 130 is secured to a sleeve portion 132 of coupling 128 in the same manner as push rod 124 is secured to sleeve portion 122 of coupling'120.
  • the right end of rack 88 is provided with a brass guide sleeve 134 in a manner similar to the guide sleeve 126 provided on the left end of rack 86.
  • band switch assembly 56 Referring now to FIGURES 5, 6, 7, 8 and 9, there are illustrated the structural and functional details of band switch assembly 56 and its related components. Since the structural features of band switch assembly 54 associated with left element 14 and those of band switch assembly 56 associated with the right half antenna element 16 are the same, only band switch assembly 56 and its related components will be described in detail. It is to be understood that the following description applies equally to the band switch assembly 54 and its related components.
  • the fiber glass push rod 124 extends from coupling 121) (FIGURE 3) through rack tube 102 and is received within an aluminum tube 60 extending to the band switch assembly 56.
  • the left end of aluminum tube 60 is flared outwardly at 136 and is coupled with the right end of rack tube 102 by means of insulator tubing 138 of phenolic material which is secured to the outer surfaces of tubes 102 and 60 as by a press fit.
  • Insulator tubing 138 and rack tube 110 are secured to each other by means of a brass bracket 140 having an aperture 142 for receiving tubing 138 and a second aperture 144 through which a brass plug 146 is received and extends within the right end of tube 110, as viewed in FIGURE 5, for purposes of securing tubes 110 and 138 together in spaced relationship.
  • Aluminum tubing 60 is secured to the aluminum sleeve of antenna element 16 by means of suitable clamp brackets 148.
  • the hollow resonator coil assembly 24 (FIGURES 7 and 8) is secured to the outwardly extending end of antenna sleeve 20 and comprises an insulator sleeve 150, which is preferably constructed of laminated phenolic material.
  • An inductor coil 152 is helically wound on the exterior surface of insulator 150 and is connected at each end to cadmium plated brass end caps 154 and 156 by means of terminals 158 and 160, respectively.
  • Endrcap 154 coaxially surrounds a portion of the length of insulator 150 adjacent one end thereof, and is suitably secured thereto as by a press fit.
  • end cap 154 includes a depending cylindrical portion 162 which is received within the outwardly directed end of antenna sleeve 20 and secured in place by means of a clamp 164 wrapped tightly about the exterior surface of sleeve 20.
  • End cap 156 coaxially surrounds insulator 150 for a portion of its length adjacent its other end and is secured thereto as by a press fit.
  • End cap 156 is provided with a cylindrical sleeve portion 165 of smaller diameter than insulator 150 and serves to receive therein the aluminum elongated cylindrical antenna sleeve member 28 in a tightly press fitted relationship so as to obtain a good electrical contact between end cap 156 and sleeve 28.
  • a fiber glass antenna member push rod 166 extends coaxially through resonator assembly 24 and is secured at its outer end (not shown) to extenda'ble aluminum antenna member 32 so as to provide retraction and extension of the antenna member.
  • the structural details and function of push rod 166 are described in greater detail in my co-pending parent application, Ser. No. 327,713.
  • the band switch assembly 56 includes a cadmium plated brass sleeve 168 suitably secured to end cap 154 by means of a metal clamp 1711 and bolts 172 so as to be in coaxial alignment with the right end of aluminum tube 60, as viewed in FIGURE 7.
  • Sleeve 168 is provided with a necked end portion 174 having threading 176 provided on its outer surface.
  • a slip-on connector nut 178 provided with threading 186 on its inner surface is mounted on the right end of tubing 68 and prevented from axial displacement therefrom by means of an outwardly radially extending flared portion 182 on the extreme right end of tube 60.
  • Tube 60 is secured in coaxial alignment to sleeve 16 8 by threading connector nut 180 on the neck portion 174 of sleeve 168 by virtue of threadings 176 and 180.
  • Sleeve 168 is counterbored to provide three coaxial axially extending bore portions 184, 186 and 188 extending from right to left, as viewed in FIGURE 8, of successively decreased diameters.
  • Bore portion 188' extends through the neck portion 174 of sleeve 168 and serves to receive a rear stationary contact 191) in press fitted relationship.
  • Rear contact 190' takes the form of an annular sleeve having a cylindrical barrel portion 192 within bore 188 of sleeve 168 and a contact portion 194 which prior to assembly is tapered radially inward from left to right, as viewed in FIGURE 8.
  • the contact portion 194 of contact 198 is provided with two notched cut-out portions on diametrically opposite sides, one only being shown in FIGURE 8, defining two diametrically opposed contact prongs 198 and 200, which are resiliently biased radially inward toward each other.
  • Contact 190' is preferably constructed of non-magnetic electrically conductive resilient material, such as spring tempered brass which has been silver plated at least on its inner surface.
  • the right end, as viewed in FIGURES 7 and 8, of sleeve 202 is received within a bore 204 of a brass sleeve 286 and tightly secured thereto as by a press fit.
  • Sleeve 286 is provided with a second axially extending bore portion 288 which receives a forward stationary contact 190a in secured relationship, as by a press fit.
  • Forward contact 190a is substantially identical with rear contact 190 and, accordingly, like portions thereof are labeled with like character references. However, the contact prongs 198 and 200 of forward contact 190w extend toward contact prongs 198 and 206 of rear contact 190, as illustrated in FIGURE 8.
  • Sleeve 206 includes an axially extending flange portion 210 on the right end thereof, as viewed in FIGURE 8, which is provided with an aperture 212 for receiving the shank portion 214 of a threaded terminal bolt 216, as illustrated in FIGURE 9'.
  • Threaded bolt 216 extends through a cadmium plated brass sleeve 218 and is threaded through a threaded aperture 228 of an arouate metal anchor 222 which is secured to insulator as by nut and bolt assemblies 224. In this manner, switch assembly 56 is secured in place on the resonator assembly 24.
  • Anchor 222 also serves to secure a cadmium plated steel conductor strap 226 in place on insulator 1511.
  • Conductor strap 226 is in turn provided with a hook portion 228 which is tightly clamped to inductor coil 152 intermediate its ends whereby a good electrical circuit path is obtained from coil 152 through strap 226, anchor 222, bolt 216 and sleeve 218, flange 216*, sleeve 206, forward contact a.
  • conductor strap 226 is secured to inductor coil 152 at a location such that the coil portion 152b, i.e., that portion between terminal stud 216 and terminal 168, serves as a 40 meter band resonator coil and that the entire coil 152, i.e., between terminals 158 and 160, serves as an 80 meter band resonator coil.
  • inductor coil 152 of the resonator assembly 24 is coated with a suitable coil coating and then covered by means of an insulator sleeve of protective material as by placing the resonator assembly and sleeve in an oven and heat shrink fitting the sleeve to the assembly.
  • the right end of push rod 124 is received within a bore 232 of sleeve portion 234 of a movable rear contact 236.
  • the sleeve portion 234 of contact 236 is secured to rod 124 in a suitable manner, as by crimping the sleeve portion in a radially inward direction so as to tightly grasp rod 124.
  • the outer diameter of sleeve portion 234 is of a dimension to provide sliding movementin an axial direction within tube 61).
  • contact 236 is provided with a smooth cylindrical shank portion 238 which extends axially through rear stationary contact 190.
  • movable rear contact 236 is constructed of non-magnetic material such as brass and at least along its shank portion 238 .is silver plated.
  • Shank portion 238 has an outer diameter suflicient to obtain frictional contact with the inner surface of stationary contact 190 at least for that portion defined by contact prongs 198 and 280, which as described hereinbefore, are resiliently biased radially inward. In this manner good electrical contact is obtained between shank portion 238 of movable contact 236 and stationary contact 190.
  • the shank portion 238 of movable contact 236 is provided with a depending axially extending stud portion 240 of smaller diameter than shank portion 238 and extends therefrom toward the right, as viewed in FIGURE 8. Stud portion 240 is received within an axially extending bore 242 of an electrically conductive non-magnetic sleeve 244 such as hard-drawn brass tubing. Stud portion 240 may be secured in any suitable manner to sleeve 244, such as by soldering at 246. Sleeve 244 extends axially through insulator tubing 282 and serves to receive within its bore 242 at the right end thereof, as viewed in FIGURE 8, a stud portion 248 of forward movable contact 250.
  • contact 250 is constructed of non-magnetic ma terial, such as silver plated brass, and includes a nose portion 254 chamfered at its left end 256, as viewed in FIGURE 8, and a rounded-off cam nose 258 at its right end.
  • the body portion 260 of contact 250 is preferably cylindrical and of a diameter sufficient to obtain frictional contact with the inner surfaces of prongs 198 and 200 of forward stationary contact 1190a.
  • a short circuit electrical path is obtained between terminal bolt 216 and terminal 158 on resonator assembly 2450 as to short circuit coil portion 152a of the resonator coil 152.
  • This electrical circuit includes the left end of coil portion 15212, as viewed in FIGURES 7 and 8, conductor strap 226, an chor plate 222, terminal 216, sleeve 206, forward stationary contact 190a, forward movable contact 250, brass sleeve 244, rear movable contact 236, rear stationary contact 198', sleeve 168, bracket 170 and cap 154.
  • rear movable contact 236, sleeve 244 and forward movable contact 250 define a shorting bar 251.
  • Limit switch 264 comprises a pair of contact reeds 268 and 270 mounted in spaced relationship by means of an insulator block 272 secured by suitable means to the housing support bracket 67.
  • limit switch 266 comprises a pair of contact reeds 274 and 276 mounted in spaced relationship to each other by means of insulator block 272.
  • Contact reeds 270 and 274 extend beyond reeds 268 and 276 and are respectively secured at their extended ends to opposite sides of a limit switch actuator 278.
  • An elongated rod 280 is provided within chamber 74 of hous' ing 70.
  • rod 280 includes an axially extending portion 282 slidably received within the right end of tube 100 between the inner surface of the tube and rack 86.
  • Adjacent portion 282, rod 280 is provided with a U-shaped portion 284 defined by legs 286, 288 and 290 (leg 290 being best shown in FIGURE 2).
  • Link portion 292 at the extreme right end of rod 280, as viewed in FIGURE 3, extends through a bore 298 in switch actuator 278.
  • Leg 282 and loop portion 296 of rod 280 are respectively located in the travel paths of sleeves 126 and 118 secured to rack 86 and are spaced from each other by distance relative to the facing surfaces of sleeves 118 and 126 so that just before rack 86 is fully retracted, sleeve 118 will engage loop portion 294 and thereby push rod 288 to the left, as viewed in FIGURE 3.
  • switch 266 With. rack 86 in its fully retracted position, as shown in FIGURE 3, switch 266 is open.
  • sleeeve 126 will engage leg portion 282 pushing rod 280 to the right, as viewed in FIGURE 3, to open limit switch 264.
  • Contact reeds 270 and 274 are spring biased toward each other so that when rack 86 is between its fully retracted and fully extended positions, the limit switches 264 and 266 will :be closed.
  • Band switch control circuit Referring now to FIGURE 10, there is illustrated a schematic circuit diagram of the band switch control circuit housed within control console 44, for purposes of controlling the operation of reversible AC motor 76 in conjunction with limit switches 264 and 266.
  • the control circuit includes a transformer core 300 having a primary winding 302 wound thereon and connected across an alternating voltage source 304 via armature 306 and contacts 368 and 319 of a doublepole, double-throw switch S.
  • Transformer core 360 has a secondary winding 312 wound thereon having terminals 314 and 316 at opposite ends of the winding.
  • Terminal 316 is directly connected with terminal 1 of the control circuit and to motor 76 via normally closed, push-button switch 50 and terminal 4 of the control circuit.
  • Terminal-s 1, 2, 3 and 4 of the control circuit are utilized in conjunction with the band tuning operation of antenna 16, which is the subject of my copending parent application, Ser. No. 327,713, to which reference is made for an understanding of the band tuning operation.
  • Terminals 4, 5 and 6 of the control circuit are utilized in conjunction with the band switching opera tion of antenna 10 to which the present invention is directed.
  • Switch lever 47 on the face of control console 44 (see FIGURE 1), is connected to andoperates an armature 318 of double-pole, double-throw switch S provided for reversing the operation of motor 76.
  • Switch S includes a Lo position contact 328 corresponding tothe L0 position of switch lever 47 and a Hi position contact 322 corresponding with the Hi position of switch lever 47.
  • the armature 318 of switch S is connected to the terminal 314 of the secondary winding 312 via motor energized indicating lamp 52 connected in parallel with a resistor 324.
  • the band switching-band tuning slide switch 66 mounted on top of control console 44 takes the form of a double-pole, double-throw switch including armatures 326 and 328.
  • Armature 326 serves to connect contact 320 with either Lo contact 330 connected to L0 terminal 5 for band switching operation, or with Lo contact 332 connected to L0 terminal 2 for band tuning operation.
  • armature 328 serves to electrically connect contact 322 with either Hi contact 334 connected to Hi terminal 6 for band switching operation, or to Hi contact 336 connected to Hi terminal 3 for band tuning operation.
  • the motor control circuit for controlling motor 76 is so arranged that when armature 318 is connected to contact 322 and armature 328 is connected with contact 334, the motor will operate to drive gear racks 86 and 88 toward their fully extended positions to obtain high frequency or 40 meter band operation. Conversely, when armature 318 is connected with contact 320 and armature 326 is connected with contact 330, motor 76 will operate to drive the gear racks 86 and 88 toward their fully re- Q tracted positions for low frequency or 80 meter band operation.
  • Band switch operation During operation of antenna 10 the operator may find it desirable to operate on either the 40 meter band or the 80 meter band. Assuming that the coil 152 of each resonator assembly 22 and 24 is set for 80 meter operation, i.e., with both coil portions 152a and 1521) active. The following procedure is followed to switch to 40 meter band operation. Power from the transmitter 38 to antenna is shut-off and slide switch 66 on console 44 is shifted to the left, as viewed in FIGURE 1, to its band switching position. In this manner, armatures 326 and 328 are respectively placed in electrical contact with Lo contact 330 and Hi contact 334.
  • lever 47 on the control console 44 is displaced to its Hi position (for 40 meter band operation) so that armature 318 of switch S is in electrical contact with Hi contact 322.
  • Motor energizing current will flow through the motor windings of motor 76 from terminal 314 to terminal 316 of the secondary winding 312 on transformer 369 in the following manner: through the parallel circuit of lamp 52 and resistor 324, armature 318, Hi contact 322, armature 328, Hi contact 334, Hi terminal 6, limit switch 264, through the motor energizing windings or" motor 76, terminal 4, switch 50 and terminal 1.
  • motor 76 is energized so that its output shaft 8%) drives the drive gear 82 via gear train 84 in a clockwise direction, as viewed in FIGURE 3.
  • the gear teeth 94 of drive gear 82 will mesh with gear teeth 90 and 92 of gear racks 86 and 38, respectively, so as to drive rack 86 to the right and rack 88 to the left, as viewed in FIGURE 3, toward their fully extended positions.
  • limit switch 266 will close, but no current will flow therethrough since armature 318 of switch S is in contact with Hi contact 322.
  • movable contact 250 As the cam nose 258 of movable contact 250' is received by contact 19011, the radially inward resiliently biased contact prongs 198 and 200 are spread apart slightly so as to receive the cylindrical shank portion 260 of contact 250. In this manner, movable contact 250 is resiliently held in place in its extended position, whereby an electrical circuit is obtained between terminal post 216 connected to coil 152 and terminal 158 so as to effectively short circuit coil portion 152a leaving only coil portion 152]) as an active element for 40 meter band operation.
  • the total travel time for band switching is in the order of 15 seconds.
  • band switch assemblies 54 and 56 respectively associated with resonator assemblies 22 and 24, together with their associated components are arranged so that short circuiting of coil portion 152a of resonator assembly 24 occurs substantially simultaneously with short circuiting of a corresponding coil portion of resonator assembly 22.
  • the procedure to switch to meter band operation is similar to that as described above with respect to switching to 40 meter band operation.
  • power from transmitter 38 to antenna 10 is shut off and slide switch 66 on control console 44 is switched to the left, as viewed in FIGURE 1, to its band switching position.
  • lever 47 on control console 44 is displaced to its Lo position (for 80 meter band operation) so that armature 318 of switch S is in electrical contact with Lo contact 326.
  • motor energizing current will flow through the windings of motor 76 from terminal 314 to terminal 316 of the secondary winding 312 on transformer 300 through: the parallel circuit of lamp 52 and resistor 324, armature 318, L0 contact 320, armature 326, L0 contact 330, L0 terminal 5, limit switch 266, through the motor energizing windings of motor 76, terminal 4, switch 50 and terminal 1.
  • motor 76 is energized so that its output shaft 80 drives the drive gear 82 via gear train 84 in a counterclockwise direction, as viewed in FIGURE 3.
  • gear racks 86 and 88 will be driven so that rack 86 will be displaced toward the left and rack 88 will be displaced toward the right, as viewed in FIGURE 3, toward their fully retracted positions.
  • limit switch 264 will close, but will pass no current since armature 318 of switch S is in contact with Lo contact 320.
  • lamp 52 will be energized as it is in the motor energizing circuit of motor 76 and, hence, will indicate to the operator stationed at the remotely located console 44 that motor 76 is energized.
  • tuning antenna 10 Upon completion of band switching operation, slide switch 66 is displaced toward the right, as viewed in FIGURE 1, to the band tuning position so that the operator may tune antenna 10.
  • the operation of tuning antenna 10 is described in detail in my copending parent application, Ser. No. 327,713.
  • the tuning operation is obtained by energizing a pair of motors located within housing 12, which motors serve to selectively extend and retract antenna elements 30 and 32.
  • the motors are energized so as to fully retract both of the antenna elements 30 and 32 so that an antenna length is defined which corresponds to a resonant frequency outside the high frequency end of the frequency band of the antenna.
  • Radio frequency power is then applied to the antenna via the feed line 42 at a frequency near the high frequency end, but within the frequency band.
  • the operator continuously monitors and measures the standing wave ratio (SWR) of the antenna 10 and of the feed line 42 by means of the SWR indicator 40.
  • the reversible motors within housing 12 are then energized to simultaneously extend both antenna elements 30 and 32 until a minimum value of the standing wave ratio (SWR) is obtained.
  • the impedance of the feed line 42 is then matched to that of the antenna 10 at the feed point by energizing the motors within housing 12 in a manner to alternately drive only one of the antenna elements 30 and 32 in opposing directions until it is established in which direction the antenna element must be driven to obtain an even smaller measurement of standing wave ratio (SWR). Thereafter, the selected antenna element is driven in that direction noted until the measurement of the value of the standing wave ratio (SWR) is at a minimum.
  • a band switch assembly adapted for use with an antenna including an elongated conductive tubular element with an electrical feed point on one end and a tubular resonator coil assembly mounted at one end to the other end of said element in substantial coaxial relationship therewith, said band switch assembly comprising: a nonmagnetic electrically conductive forward stationary contact mounted in electrical contact with and extending outwardly from the coil of said assembly intermediate the ends thereof, a nonmagnetic electrically conductive rear stationary contact mounted in electrical contact withand extending outwardly from one end of said coil adjacent said element, and an elongated nonmagnetic electrically conductive member movable between retracted and extended positions and located exteriorly of said coil and said antenna a distance sufficient so as not to materially affect the magnetic field of the coil when energized, said member having a portion thereof in continuous electrical contact with said rear stationary contact and a forward portion thereof for electrical contact with said forward stationary contact when said member is in its fully extended position to thereby short circuit said portion of the coil between said rear stationary contact and said forward stationary contact.
  • a band switch assembly as set forth in claim 1 including motive means and nonconductive push rod means connecting said movable conductive member with said motive means for extending and retracting said member.
  • An antenna including an elongated conductive tubular element having an electrical feed point at one end, a tubular resonator coil assembly mounted at one end to the other end of said element in substantially coaxial relationship therewith, a band switch assembly mounted on said antenna including a nonmagnetic electrically conductive forward stationary contact mounted in electrical contact with the coil of said assembly intermediate the ends thereof, a nonmagnetic electrically conductive rear stationary contact mounted in electrical contact with one end of said coil adjacent said element, an elongated electrically conductive nonmagnetic shorting bar movable between retracted and extended positions, said shorting bar being located exteriorly of said coil and said antenna a distance sufficient so as to not materially affect the magnetic field of the coil when energized and having a portion thereof in continuous electrical contact with said rear stationary contact and a forward portion thereof for electrical contact with said forward stationary contact when said shorting bar is in its fully extended position to thereby short circuit said portion of the coil between said rear stationary contact and said forward stationary contact, a tubular element of electrically insulating and nonmagne
  • An antenna including an elongated conductive tubular element having an electrical feed point at one end, a tubular resonator coil assembly mounted at one end to the other end of said element in substantially coaxial relationship therewith, a movable antenna member movably secured to the other end of said assembly, a nonconductive rod like member extending longitudinally through said assembly and connected at one end to said antenna member for purposes of extending and retracting said antenna member to vary the overall length of the antenna, .
  • a band switch assembly mounted onsaid antenna and including a forward stationary contact mounted in electrical contact with the coil of said assembly intermediate the ends thereof, a rear stationary contact mounted in electrical contact with one end of said coil adjacent said element, and an elongated electrically conductive shorting bar movable between retracted and extended positions, said shorting bar being located exteriorly of said coil a distance sufiicient so as to not materially affect the magnetic field of the coil when energized .and having a portion thereof in continuous electrical contact with said rear stationary contact and a forward portion thereof for electrical contact
  • An antenna comprising a housing, first and second coaxially aligned, elongated conductive antenna elements extending in opposing directions from said housing, each said element having a tubular resonator coil assembly mounted at its free end in substantial coaxial relationship therewith, each said resonator coil assembly having a movable antenna member movably secured to the free end of said assembly for varying the length of said antenna, means in said housing for independently extending and retracting each said extendable antenna member, a band switch assembly mounted on each said resonator coil assembly; each said band switch assembly including a forward stationary contact mounted in electrical contact with the coil of said assembly intermediate the ends thereof, a rear stationary contact mounted in electrical contact with one end of said coil adjacent said element and an elongated electrically conductive shorting bar movable between retracted and extended positions, said shorting bar being located exteriorly of said coil a distance sufficient so as to not materially affect the magnetic field 15 of the coil when energized and having a portion thereof in continuous electrical contact with said rear stationary contact and a forward portion
  • An antenna as set forth in claim 11 including a nonconductive rod like member extending longitudinally through each said resonator assembly and connected at one end to one of said antenna members for purposes of extending and retracting said antenna member to vary the overall length of the antenna.
  • An antenna as set forth in claim 11 including reversible electric motor means and push rod means connecting each said shorting bar with said motor means to simultaneously extend or retract said shorting bars.
  • An antenna as set forth in claim 13 including motor control means for selectively energizing said reversible motor means to reversibly drive said shorting bars between their fully extended and fully retracted positions.
  • said 10 motor control means includes limit switch means responsive to the fully retracted and fully extended positions of said shorting bars to de-energize said motor means When said shorting bars are in their fully retracted or fully extended positions.

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Description

J. ALTMEYER June 20, 1967 EXTENSIBLE DIPOLE WITH ADJUSTABLE LOADING COILS 5 Sheets-Sheet 1 Filed July 2, 1964 mnv thy-.4052. 13m
INVENTOR. JOHN ALTMAYER GEIPEZM 024m 7474 7 qr f ATTOR EYS J. ALTMEYER June 20, 1967 EXTENSIBLB DIPOLE WITH ADJUSTABLE LOADING COILS Filed July 2, 1964 5 Sheets-Sheet 2 wziotim 024m INVENTOR. JOHN ALTMAYER June 1967 J. ALTMEYER EXTENSIBLE DIPOLE WITH ADJUSTABLE LOADING COILS Filed July 2, 1964 5 Sheets-Sheet 3 INVENTOR. JOHN ALTMAYER ATT June 20, 1967 J. ALTMEYER 3,327,311
EXTENSIBLE DIPOLE WITH ADJUSTABLE LOADING COILS Filed July 2, 1964 5 Sheets-Sheet 4 INVENTOR. JOHN ALTMAYER ORNEYS L LJJJJ v vV l/w ;)A
United States Patent G 3,327,311 EXTENSEBLE DIPOLE WITH ADJUSTABLE LOADING COILS John Altrneyer, Euclid, Ohio, assignor to New-Tronics, Inc., a division of Automatic Radio, Cleveland, Ohio,
a corporation of Massachusetts Filed July 2, 1964, Ser. No. 379,817 Claims. (Cl. 343750) The present application is a continuation-in-part application of my parent copending United States application, Ser. No. 327,713, filed Dec. 3, 1963.
This invention pertains to the art of radio antennas and more particularly to a radio antenna which may be remotely switched from one desired frequency band of operation to another.
The present invention is particularly applicable to a radio antenna of the type generally referred to as a dipole which is electrically energized at a point intermediate its ends, and will be described with particular reference thereto, although it will be appreciated that the invention has broader applications and may be used, for example, with end-fed quarter wave antennas.
In amateur radio work the operator often desires to use the same antenna on more than one of the several amateur hands. This has been done heretofore by using wave traps to electrically isolate the end portions of the antenna so that the remaining portion will resonate at the frequency of operation, or by using loading coils intermediate the ends of the antenna and then switching portions of the coil into and out of the effective electrical length of the antenna.
The latter method heretofore has been accomplished by providing the inside of the coil with contacts and then moving a shorting bar axially through the coil. Such an arrangement is electrically ineflicient because it introduces metal on the inside of the coil where the magnetic field is strongest and eddy currents are introduced in this metal. Also, and particularly when the coil is located near the ends of the antenna, this voltage about the coil at even relatively low power levels is so high as to are over between the contacts and the coil, or other contacts.
The present invention deals with these problems of controlling the operating frequency band of an antenna and enables the operator to remotely select a desired frequency band without the requirement of physically manipulating adjustable taps on an antenna loading coil and without electrical problems. More particularly, the band switching mechanism of the present'invention provides for selectively short circuiting a portion of the loading coil with a metal shorting bar.
In accordance with the present invention, there is provided band switching means for remotely selecting the operating frequency band of an antenna which changes the inductance of an antenna loading coil with a shorting bar which is located exteriorly of the coil a sufiicient distance so as to not materially affect the magnetic field of the coil.
In accordance with another aspect of the invention, a multi-band antenna is provided having a finite length antenna member, a resonator coil and an extendable antenna member movably secured to one end of the resonator coil. A movable shorting bar is spaced from the coil a sufficient distance so as to not materially affect the magnetic field of the coil and is remotely actuated to short circuit a portion of the coil when desired to obtain band switching.
The primary object of the present invention is to provide means for remotely selecting the operating frequency band of an antenna which is simple in construction and economical to manufacture.
Another object of the present invention is to provide band switching means for varying the inductance of an antenna loading coil without materially affecting the magnetic field of the coil.
Another object of the present invention is to provide means for changing the operating frequency band of an antenna without resorting to the use of wave traps.
A still further object of the present invention is to provide an antenna having means for remote tuning of the antenna by varying the physical length of the antenna, as well as means for remotely changing the operating frequency band of the antenna.
A still further object of the present invention is to provide antenna band switching means exhibiting minimum are over so as to permit use with a resonator coil having voltage about the coil of relatively high power level.
Another object of the present invention is to provide antenna band switching means without the use of a metal shorting bar located within the interior of the resonator coil structure.
These and other objects and advantages of the invention will become apparent from the following description used to illustrate the preferred embodiments of the invention as read in connection with the accompanying drawings in which:
FIGURE 1 is a schematic elevational view illustrating the preferred embodiment of the invention;
FIGURE 2 is an enlarged sectional view taken along line 2-2 of FIGURE 1;
FIGURE 3 is an enlarged fragmentary plan view of the antenna shown in FIGURE 1;
FIGURE 4 is an enlarged elevational view partly in section of one portion of the antenna shown in FIGURE 1;
FIGURE 5 is an enlarged plan view partly in section of another portion of the antenna shown in FIGURE 1;
FIGURE 6 is an elevational view of the portion of the antenna shown in FIGURE 5 FIGURE 7 is an enlarged elevational View partly in section of another portion of the antenna shown in FIG- URE 1;
FIGURE 8 is an enlarged sectional view of the portion of the antenna shown in FIGURE 7;
FIGURE 9 is a sectional view taken along line 9-9 of FIGURE 8; and
FIGURE 10 is a schematic circuit diagram of a motor control circuit in accordance with the invention.
General arrangement Referring now to the drawings and more particularly to FIGURE 1, there is illustrated a center fed, half wave dipole antenna 10 comprising an aluminum housing 12 having a pair of hollow coaxially aligned antenna elements 14 and 16 extending therefrom in opposing directions. Antenna element 14 is of fixed length and includes an aluminum cylindrical sleeve 18, a hollow resonator coil assembly 22 and another aluminum cy indrical sleeve 26. Similarly, antenna element 16 is of fixed length, equal to that of element 14 and includes an aluminum cylindrical sleeve 20, a hollow resonator coil assembly 24 and another aluminum cylindrical sleeve 28.
Extending coaxially from antenna elements 14 and 16 are extendable aluminum antenna members 30 and 32 respectively, shown in their fully extended positions in FIGURE 1. Radio frequency power is applied to the antenna 10 at spaced feed points or antenna terminals 34 and 36 from a transmitter 38 via a SWR (standing wave ratio) indicator or meter 40. Any suitable feed line may be used to connect terminals 34 and 36 with the transmitter 38 although, as shown in FIGURE 1, a coaxial cable 42 is provided having a characteristic im- 0 pedance of approximately 52 ohms.
Each extendable antenna member 30 and 32 is connected to a reversible motor located within the housing (not shown in FIGURE 1) for purposes of varying the length of the antenna 10 to tune the antenna. In tuning the antenna 10, utilization is made of a motor control console 44 connected to the two reversible motors within the housing 12 via lead pairs 46 and 48 to control the operation of the motors. The control console 44 includes a switch lever 47, selectively actuable to L and Hi positions for simultaneously energizing both motors to extend or retract the extendable antenna members 311 and 32. A spring biased, normally closed, push button switch 50 is provided on the top of console 44 for purposes of deenergizing one of the reversible motors so that fine tuning of the antenna may be accomplished by extending or retracting only one of the extendable antenna members 30 and 32. Further, the console 44 is provided with an indicator lamp 52 which is operative to be energized and glow brightly only when one or both of the reversible motors in housing 12 is energized.
The housing 12 comprises a left half portion 13 and a right half portion 15 separated by a suitable gasket to provide a weather tight seal and electrically insulates the two housings, one from the other. The housing portions 13 and 15 are secured together by any suitable means, such as nut and bolt assemblies, and rest in a cradle 17 and secured thereto by means of suitable straps 19.
The cradle 17 is securely mounted to the top of a post or pipe 21 in such a manner that antenna elements 14 and 16 are horizontally aligned with respect to ground level so as to thereby insure relatively constant capacitance to ground along the length of the antenna.
The description thus far has been particularly directed toward the general arrangement of the remotely tuned radio antenna described and claimed in my copending parent application, Ser. No. 327,713, identified hereinbefore, the description of which is incorporated herein by reference. The antenna structure disclosed by that application does not provide means for remotely selecting a desired operating frequency band, but is directed toward means for remotely tuning the antenna within a particular frequency band.
In accordance with the present invention there is provided means for remotely selecting a desired operating frequency band. The band selecting means according to the present invention includes a pair of band switch assemblies 54 and 56 respectively mounted on antenna elements 14 and 16 for purposes of changing the inductance of resonator coil assemblies 22 and 24 in order to obtain a desired operating frequency band. Band switch assemblies 54 and 56 are respectively controlled by extendable and retractable shorting bars (not shown in FIGURE 1) which are encased within hollow aluminum tubes 58 and 60 respectively, extending from switch assemblies 54 and 56 to a band switch motor control housing 62. In switching to a desired operating frequency band utilization is made of the motor control console 44 connected to the motor means within housing 62 via a lead pair 64. The control console 44 also includes a slide switch 66 selectively actuable to provide band switching operation, as shown in the dotted position in FIGURE 1, or band tuning operation, as shown by the solid lines.
Having briefly described the general arrangement of the invention with particular reference to FIGURE 1, attention is now directed to various structural and operative features as set forth in FIGURES 2 through 10. Since the features of both halves of the antenna 10, i.e., including the left and right half antenna elements 14 and 16 extending outwardly of housing 12 to the antenna members and 32, are the same, only the right half of antenna 10 will be described in detail. It is to be understood that the following description applies equally to the left half of the antenna 10.
Band switching control motor Referring now to FIGURES 2, 3 and 4, there are illustrated the structural and functional details of a band switching control motor. A housing support bracket 67 is secured on the top surface of antenna housing 12 by any suitablemeans, such as bolts 68. A band switch motor control housing cover 62 is removably secured to the bracket 67 as by screws 72 and defines a chamber 74 containing a reversible A.C. motor 76. Motor 76 is secured within housing 62 to the bracket 67 as by bolts 78. Motor 76 is provided with an output shaft 80 drivingly connected to a rack drive gear 82 via a suitable gear train 84.
Drive gear 82 is interposed between a pair of gear racks 86 and 88 aligned in parallel relationship with each other and together defining a plane perpendicular to the axis of rotation of drive gear 82. Gear racks 86 and 88 are respectively provided with gear teeth 90 and 92 maintained in meshed gear engagement with gear teeth 94 of drive gear 82. In this manner, upon rotation of gear 82 in a given direction about its axis of rotation, gear racks 86 and 88 will be driven in opposing parallel directions.
The opposite ends of gear rack 86 extend through apertures 96 and 98 of upstanding side walls 7 and 99 suitably secured to the support bracket 67 and are respectively received within coaxially aligned brass rack tubes 1% and 102. Similarly, the opposite ends of rack 88 extend through apertures 104 and 106 in side walls 97 and 99 and are respectively received within 'coaxially aligned brass rack tubes 108 and 110. Rack tubes and 1118 are secured to the left half portion 13 of housing 12 by means of a suitable bracket 112 so that tubes 100 and 108 are coplanar and extend in a direction parallel to antenna element 14. Similarly, rack tubes 1112 and are secured to the right half portion 15 of housing 12 by means of a bracket 114 so that tubes 102. and 110 are coplanar and extend in a direction parallel, to antenna element 16.
The right end of gear rack 86, as viewed in FIGURE 3,
is provided'with threading 116. A brass cylindrical guide sleeve 118 is threaded to a portion of threading 116 and extends therefrom, as viewed in FIGURE 3, toward drive gear 82. A cylindrical brass coupling 120 having an outer diameter equal to that of sleeve 118 is threaded to the remaining portion of threading 116 on rack 86 and includes a depending cylindrical sleeve portion 122 which extends axially to the right of threading 116. The cylindrical sleeve portion 122 serves to receive a fiber glass push rod 124, as shown in FIGURE 3. The sleeve portion 122 is fastened securely to push rod 124 as by staking the sleeve, to the rod which may be accomplished by utilizing a suitable tool to squeeze sleeve portion 122 radially inward into tightly gripping fashion with rod 124. Similarly, brass sleeve 118 is staked to gear rack 86. The left end of gear rack 86 has mounted thereon a brass guide sleeve 126 which is tightly secured to the rack as by staking. The outer diameters of guide sleeves 126 and 118 are of a dimension to obtain a sliding fit with the inner surfaces of rack tubes 100 and 102 respectively, whereby alignment of rack 86 is obtained throughout its movement within tubes 100 and 102.
Similarly to that of gear rack 86, gear rack 88 is also provided with guide sleeves at its opposing ends. Thus the left end portion of gearrack 88, as viewed in FIGURE 3,
is provided with a brass guide sleeve 127 and a brass coupling 128 which are threaded and staked on rack 88 in the same manner as sleeve 118 and coupling 121 are threaded and staked on rack 86. A fiber glass push rod 130 is secured to a sleeve portion 132 of coupling 128 in the same manner as push rod 124 is secured to sleeve portion 122 of coupling'120. The right end of rack 88,. as viewed in FIGURE 5, is provided with a brass guide sleeve 134 in a manner similar to the guide sleeve 126 provided on the left end of rack 86.
Band switching mechanism Referring now to FIGURES 5, 6, 7, 8 and 9, there are illustrated the structural and functional details of band switch assembly 56 and its related components. Since the structural features of band switch assembly 54 associated with left element 14 and those of band switch assembly 56 associated with the right half antenna element 16 are the same, only band switch assembly 56 and its related components will be described in detail. It is to be understood that the following description applies equally to the band switch assembly 54 and its related components.
Referring now to FIGURES 5 and 6, the fiber glass push rod 124 extends from coupling 121) (FIGURE 3) through rack tube 102 and is received within an aluminum tube 60 extending to the band switch assembly 56. The left end of aluminum tube 60, as viewed in FIGURE 5, is flared outwardly at 136 and is coupled with the right end of rack tube 102 by means of insulator tubing 138 of phenolic material which is secured to the outer surfaces of tubes 102 and 60 as by a press fit. Insulator tubing 138 and rack tube 110 are secured to each other by means of a brass bracket 140 having an aperture 142 for receiving tubing 138 and a second aperture 144 through which a brass plug 146 is received and extends within the right end of tube 110, as viewed in FIGURE 5, for purposes of securing tubes 110 and 138 together in spaced relationship. Aluminum tubing 60 is secured to the aluminum sleeve of antenna element 16 by means of suitable clamp brackets 148.
The hollow resonator coil assembly 24 (FIGURES 7 and 8) is secured to the outwardly extending end of antenna sleeve 20 and comprises an insulator sleeve 150, which is preferably constructed of laminated phenolic material. An inductor coil 152 is helically wound on the exterior surface of insulator 150 and is connected at each end to cadmium plated brass end caps 154 and 156 by means of terminals 158 and 160, respectively. Endrcap 154 coaxially surrounds a portion of the length of insulator 150 adjacent one end thereof, and is suitably secured thereto as by a press fit. Also, end cap 154 includes a depending cylindrical portion 162 which is received within the outwardly directed end of antenna sleeve 20 and secured in place by means of a clamp 164 wrapped tightly about the exterior surface of sleeve 20. End cap 156 coaxially surrounds insulator 150 for a portion of its length adjacent its other end and is secured thereto as by a press fit. End cap 156 is provided with a cylindrical sleeve portion 165 of smaller diameter than insulator 150 and serves to receive therein the aluminum elongated cylindrical antenna sleeve member 28 in a tightly press fitted relationship so as to obtain a good electrical contact between end cap 156 and sleeve 28. A fiber glass antenna member push rod 166 extends coaxially through resonator assembly 24 and is secured at its outer end (not shown) to extenda'ble aluminum antenna member 32 so as to provide retraction and extension of the antenna member. The structural details and function of push rod 166 are described in greater detail in my co-pending parent application, Ser. No. 327,713.
The band switch assembly 56 includes a cadmium plated brass sleeve 168 suitably secured to end cap 154 by means of a metal clamp 1711 and bolts 172 so as to be in coaxial alignment with the right end of aluminum tube 60, as viewed in FIGURE 7. Sleeve 168 is provided with a necked end portion 174 having threading 176 provided on its outer surface. A slip-on connector nut 178 provided with threading 186 on its inner surface is mounted on the right end of tubing 68 and prevented from axial displacement therefrom by means of an outwardly radially extending flared portion 182 on the extreme right end of tube 60. Tube 60 is secured in coaxial alignment to sleeve 16 8 by threading connector nut 180 on the neck portion 174 of sleeve 168 by virtue of threadings 176 and 180.
Sleeve 168 is counterbored to provide three coaxial axially extending bore portions 184, 186 and 188 extending from right to left, as viewed in FIGURE 8, of successively decreased diameters. Bore portion 188' extends through the neck portion 174 of sleeve 168 and serves to receive a rear stationary contact 191) in press fitted relationship. Rear contact 190' takes the form of an annular sleeve having a cylindrical barrel portion 192 within bore 188 of sleeve 168 and a contact portion 194 which prior to assembly is tapered radially inward from left to right, as viewed in FIGURE 8. The contact portion 194 of contact 198 is provided with two notched cut-out portions on diametrically opposite sides, one only being shown in FIGURE 8, defining two diametrically opposed contact prongs 198 and 200, which are resiliently biased radially inward toward each other. Contact 190' is preferably constructed of non-magnetic electrically conductive resilient material, such as spring tempered brass which has been silver plated at least on its inner surface.
A tubular sleeve of insulating material, such as laminated phenolic, is received within the bore 184 of brass sleeve 168 and is secured thereto as by a press fit so that the sleeve 282 extends in coaxial relationship with sleeve 168. The right end, as viewed in FIGURES 7 and 8, of sleeve 202 is received within a bore 204 of a brass sleeve 286 and tightly secured thereto as by a press fit. Sleeve 286 is provided with a second axially extending bore portion 288 which receives a forward stationary contact 190a in secured relationship, as by a press fit. Forward contact 190a is substantially identical with rear contact 190 and, accordingly, like portions thereof are labeled with like character references. However, the contact prongs 198 and 200 of forward contact 190w extend toward contact prongs 198 and 206 of rear contact 190, as illustrated in FIGURE 8.
Sleeve 206 includes an axially extending flange portion 210 on the right end thereof, as viewed in FIGURE 8, which is provided with an aperture 212 for receiving the shank portion 214 of a threaded terminal bolt 216, as illustrated in FIGURE 9'. Threaded bolt 216 extends through a cadmium plated brass sleeve 218 and is threaded through a threaded aperture 228 of an arouate metal anchor 222 which is secured to insulator as by nut and bolt assemblies 224. In this manner, switch assembly 56 is secured in place on the resonator assembly 24. Anchor 222 also serves to secure a cadmium plated steel conductor strap 226 in place on insulator 1511. Conductor strap 226 is in turn provided with a hook portion 228 which is tightly clamped to inductor coil 152 intermediate its ends whereby a good electrical circuit path is obtained from coil 152 through strap 226, anchor 222, bolt 216 and sleeve 218, flange 216*, sleeve 206, forward contact a. Preferably, conductor strap 226 is secured to inductor coil 152 at a location such that the coil portion 152b, i.e., that portion between terminal stud 216 and terminal 168, serves as a 40 meter band resonator coil and that the entire coil 152, i.e., between terminals 158 and 160, serves as an 80 meter band resonator coil. This may be obtained, for example, in the construction illustrated in FIGURES 7 and 8 by providing 181% turns of 16- gauge aluminum wire for the coil portion 152a, i.e., between terminal 158 and terminal bolt 216, and that the coil portion 152!) include 82 /2 turns of 16 gauge aluminum wire. Preferably, inductor coil 152 of the resonator assembly 24 is coated with a suitable coil coating and then covered by means of an insulator sleeve of protective material as by placing the resonator assembly and sleeve in an oven and heat shrink fitting the sleeve to the assembly.
The right end of push rod 124, as viewed in FIGURES 7 and 8, is received within a bore 232 of sleeve portion 234 of a movable rear contact 236. The sleeve portion 234 of contact 236 is secured to rod 124 in a suitable manner, as by crimping the sleeve portion in a radially inward direction so as to tightly grasp rod 124. The outer diameter of sleeve portion 234 is of a dimension to provide sliding movementin an axial direction within tube 61). Extending axially toward the right from sleeve portion 234, as viewed in FIGURE 8, contact 236 is provided with a smooth cylindrical shank portion 238 which extends axially through rear stationary contact 190. Preferably, movable rear contact 236 is constructed of non-magnetic material such as brass and at least along its shank portion 238 .is silver plated. Shank portion 238 has an outer diameter suflicient to obtain frictional contact with the inner surface of stationary contact 190 at least for that portion defined by contact prongs 198 and 280, which as described hereinbefore, are resiliently biased radially inward. In this manner good electrical contact is obtained between shank portion 238 of movable contact 236 and stationary contact 190.
The shank portion 238 of movable contact 236 is provided with a depending axially extending stud portion 240 of smaller diameter than shank portion 238 and extends therefrom toward the right, as viewed in FIGURE 8. Stud portion 240 is received within an axially extending bore 242 of an electrically conductive non-magnetic sleeve 244 such as hard-drawn brass tubing. Stud portion 240 may be secured in any suitable manner to sleeve 244, such as by soldering at 246. Sleeve 244 extends axially through insulator tubing 282 and serves to receive within its bore 242 at the right end thereof, as viewed in FIGURE 8, a stud portion 248 of forward movable contact 250. Stud portion 248 of contact 259 may be secured to sleeve 244 in any suitable manner, such as by soldering at 252. Preferably, contact 250 is constructed of non-magnetic ma terial, such as silver plated brass, and includes a nose portion 254 chamfered at its left end 256, as viewed in FIGURE 8, and a rounded-off cam nose 258 at its right end. The body portion 260 of contact 250 is preferably cylindrical and of a diameter sufficient to obtain frictional contact with the inner surfaces of prongs 198 and 200 of forward stationary contact 1190a. In this manner when forward movable contact 250 is received by forward stationary contact 190a, a short circuit electrical path is obtained between terminal bolt 216 and terminal 158 on resonator assembly 2450 as to short circuit coil portion 152a of the resonator coil 152. This electrical circuit includes the left end of coil portion 15212, as viewed in FIGURES 7 and 8, conductor strap 226, an chor plate 222, terminal 216, sleeve 206, forward stationary contact 190a, forward movable contact 250, brass sleeve 244, rear movable contact 236, rear stationary contact 198', sleeve 168, bracket 170 and cap 154. Thus, rear movable contact 236, sleeve 244 and forward movable contact 250 define a shorting bar 251.
Limit switch Referring now to FIGURE 4, there are illustrated a pair of limit switches 264 and 266. Limit switch 264 comprises a pair of contact reeds 268 and 270 mounted in spaced relationship by means of an insulator block 272 secured by suitable means to the housing support bracket 67. Similarly, limit switch 266 comprises a pair of contact reeds 274 and 276 mounted in spaced relationship to each other by means of insulator block 272. Contact reeds 270 and 274 extend beyond reeds 268 and 276 and are respectively secured at their extended ends to opposite sides of a limit switch actuator 278. An elongated rod 280 is provided within chamber 74 of hous' ing 70. Proceeding from left to right, as viewed in FIG- URE 3, rod 280 includes an axially extending portion 282 slidably received within the right end of tube 100 between the inner surface of the tube and rack 86. Adjacent portion 282, rod 280 is provided with a U-shaped portion 284 defined by legs 286, 288 and 290 (leg 290 being best shown in FIGURE 2). Leg 290, together with another leg portion 292, form a loop portion 284 defining an eyelet 296 just sufficient in dimension to permit noninterference with the movement of rack 86. Link portion 292 at the extreme right end of rod 280, as viewed in FIGURE 3, extends through a bore 298 in switch actuator 278. Leg 282 and loop portion 296 of rod 280 are respectively located in the travel paths of sleeves 126 and 118 secured to rack 86 and are spaced from each other by distance relative to the facing surfaces of sleeves 118 and 126 so that just before rack 86 is fully retracted, sleeve 118 will engage loop portion 294 and thereby push rod 288 to the left, as viewed in FIGURE 3. With. rack 86 in its fully retracted position, as shown in FIGURE 3, switch 266 is open. Similarly, just before rack 86 is in its fully extended position, corresponding with the position of push rod 124 as illustrated in FIGURE 8, sleeeve 126 will engage leg portion 282 pushing rod 280 to the right, as viewed in FIGURE 3, to open limit switch 264. Contact reeds 270 and 274 are spring biased toward each other so that when rack 86 is between its fully retracted and fully extended positions, the limit switches 264 and 266 will :be closed.
Band switch control circuit Referring now to FIGURE 10, there is illustrated a schematic circuit diagram of the band switch control circuit housed within control console 44, for purposes of controlling the operation of reversible AC motor 76 in conjunction with limit switches 264 and 266.
The control circuit includes a transformer core 300 having a primary winding 302 wound thereon and connected across an alternating voltage source 304 via armature 306 and contacts 368 and 319 of a doublepole, double-throw switch S. Transformer core 360 has a secondary winding 312 wound thereon having terminals 314 and 316 at opposite ends of the winding. Terminal 316 is directly connected with terminal 1 of the control circuit and to motor 76 via normally closed, push-button switch 50 and terminal 4 of the control circuit. Terminal- s 1, 2, 3 and 4 of the control circuit, as illustrated in FIGURE 10, are utilized in conjunction with the band tuning operation of antenna 16, which is the subject of my copending parent application, Ser. No. 327,713, to which reference is made for an understanding of the band tuning operation. Terminals 4, 5 and 6 of the control circuit are utilized in conjunction with the band switching opera tion of antenna 10 to which the present invention is directed.
Switch lever 47, on the face of control console 44 (see FIGURE 1), is connected to andoperates an armature 318 of double-pole, double-throw switch S provided for reversing the operation of motor 76. Switch S includes a Lo position contact 328 corresponding tothe L0 position of switch lever 47 and a Hi position contact 322 corresponding with the Hi position of switch lever 47. The armature 318 of switch S is connected to the terminal 314 of the secondary winding 312 via motor energized indicating lamp 52 connected in parallel with a resistor 324.
The band switching-band tuning slide switch 66 mounted on top of control console 44 takes the form of a double-pole, double-throw switch including armatures 326 and 328. Armature 326 serves to connect contact 320 with either Lo contact 330 connected to L0 terminal 5 for band switching operation, or with Lo contact 332 connected to L0 terminal 2 for band tuning operation. Similarly, armature 328 serves to electrically connect contact 322 with either Hi contact 334 connected to Hi terminal 6 for band switching operation, or to Hi contact 336 connected to Hi terminal 3 for band tuning operation.
The motor control circuit for controlling motor 76 is so arranged that when armature 318 is connected to contact 322 and armature 328 is connected with contact 334, the motor will operate to drive gear racks 86 and 88 toward their fully extended positions to obtain high frequency or 40 meter band operation. Conversely, when armature 318 is connected with contact 320 and armature 326 is connected with contact 330, motor 76 will operate to drive the gear racks 86 and 88 toward their fully re- Q tracted positions for low frequency or 80 meter band operation.
It will be observed from FIGURE that when motor 76 is energized so as to drive gear racks '86 and 88 toward their fully extended positions, lamp 52 will be in the motor energizing circuit and will glow brightly until the gear racks reach their fully extended positions causing limit switch 264 to open. Similarly, when motor 76 is energized in a manner to retract gear racks 86 and 83 toward their fully retracted positions, lamp 52 will glow brightly until both racks reach their fully extended positions causing limit switch 266 to open. In this manner, an operator stationed at the control console 44 is informed by lamp 52 whether motor 76 is energized.
Band switch operation During operation of antenna 10 the operator may find it desirable to operate on either the 40 meter band or the 80 meter band. Assuming that the coil 152 of each resonator assembly 22 and 24 is set for 80 meter operation, i.e., with both coil portions 152a and 1521) active. The following procedure is followed to switch to 40 meter band operation. Power from the transmitter 38 to antenna is shut-off and slide switch 66 on console 44 is shifted to the left, as viewed in FIGURE 1, to its band switching position. In this manner, armatures 326 and 328 are respectively placed in electrical contact with Lo contact 330 and Hi contact 334. Next, lever 47 on the control console 44 is displaced to its Hi position (for 40 meter band operation) so that armature 318 of switch S is in electrical contact with Hi contact 322. Motor energizing current will =flow through the motor windings of motor 76 from terminal 314 to terminal 316 of the secondary winding 312 on transformer 369 in the following manner: through the parallel circuit of lamp 52 and resistor 324, armature 318, Hi contact 322, armature 328, Hi contact 334, Hi terminal 6, limit switch 264, through the motor energizing windings or" motor 76, terminal 4, switch 50 and terminal 1. In this manner, motor 76 is energized so that its output shaft 8%) drives the drive gear 82 via gear train 84 in a clockwise direction, as viewed in FIGURE 3. The gear teeth 94 of drive gear 82 will mesh with gear teeth 90 and 92 of gear racks 86 and 38, respectively, so as to drive rack 86 to the right and rack 88 to the left, as viewed in FIGURE 3, toward their fully extended positions. As the gear racks are being driven, limit switch 266 will close, but no current will flow therethrough since armature 318 of switch S is in contact with Hi contact 322.
During the movement of racks 86 and 88 toward their fully extended positions, lamp 52 will be energized as it is in the motor energizing circuit of motor 76 and, hence, will indicate to the operator stationed at the remotely located console 44 that motor 76 is energized. The outward movement of racks 86 and 88 will in turn cause outward movement of push rods 124 and 126 respectively. P ush rods 124 and 126 each respectively control the switching operation of band switches 56 and 54 in identical manners. Thus, for example, with reference to FIGURES 7 and 8, the outward movement of push rod 124 displaces shorting bar 251 from its retracted position, as shown in FIGURE 7, to its fully extended position, as shown in FIGURE 8. However, just before movable contact 250 is received by forward stationary contact 190a, sleeve 126 fixed on rack 86 will engage rod portion 282 of rod 289, pushing the rod to the right, as viewed in FIGURE 3, whereby switch actuator 278 will also be displaced causing limit switch 264 to open. Upon opening of limit switch 264 indicator lamp 52 will cease to glow and motor 76 will be de-energized. Movable switch contact 250, however, will continue to travel toward the right, as viewed in FIGURES 7 and 8, a slight amount due to its momentum and will be received by forward contact 190a. As the cam nose 258 of movable contact 250' is received by contact 19011, the radially inward resiliently biased contact prongs 198 and 200 are spread apart slightly so as to receive the cylindrical shank portion 260 of contact 250. In this manner, movable contact 250 is resiliently held in place in its extended position, whereby an electrical circuit is obtained between terminal post 216 connected to coil 152 and terminal 158 so as to effectively short circuit coil portion 152a leaving only coil portion 152]) as an active element for 40 meter band operation. The total travel time for band switching is in the order of 15 seconds. The band switch assemblies 54 and 56 respectively associated with resonator assemblies 22 and 24, together with their associated components are arranged so that short circuiting of coil portion 152a of resonator assembly 24 occurs substantially simultaneously with short circuiting of a corresponding coil portion of resonator assembly 22.
If the resonator assemblies 22 and 24 are set for'40 meter band operation, i.e., with coil portion 152a short circuited, the procedure to switch to meter band operation is similar to that as described above with respect to switching to 40 meter band operation. Hence, power from transmitter 38 to antenna 10 is shut off and slide switch 66 on control console 44 is switched to the left, as viewed in FIGURE 1, to its band switching position. However, lever 47 on control console 44 is displaced to its Lo position (for 80 meter band operation) so that armature 318 of switch S is in electrical contact with Lo contact 326. Thus, motor energizing current will flow through the windings of motor 76 from terminal 314 to terminal 316 of the secondary winding 312 on transformer 300 through: the parallel circuit of lamp 52 and resistor 324, armature 318, L0 contact 320, armature 326, L0 contact 330, L0 terminal 5, limit switch 266, through the motor energizing windings of motor 76, terminal 4, switch 50 and terminal 1. In this manner, motor 76 is energized so that its output shaft 80 drives the drive gear 82 via gear train 84 in a counterclockwise direction, as viewed in FIGURE 3. Thus, gear racks 86 and 88 will be driven so that rack 86 will be displaced toward the left and rack 88 will be displaced toward the right, as viewed in FIGURE 3, toward their fully retracted positions. As the gear racks are being driven limit switch 264 will close, but will pass no current since armature 318 of switch S is in contact with Lo contact 320. During the movement of racks 86 and 88 toward their fully retracted positions, lamp 52 will be energized as it is in the motor energizing circuit of motor 76 and, hence, will indicate to the operator stationed at the remotely located console 44 that motor 76 is energized.
The inward movement of racks 86 and 88 will in turn cause inward movement of push rods 124 and 126, respectively, whereby band switch assemblies 54 and 56 will be rendered open, i.e., coil portion 152a of each resonator assembly will no longer be short circuited. Just before racks 86 and 88 reach their fully retracted positions sleeve 118 on rack 86 will engage loop portion 294 of rod 280 causing the rod to be displaced toward the left, as viewed in FIGURE 3, opening limit switch 266, as shown in FIGURE 4. Hence, indicator lamp 52 will be de-energized indicating to the operator that motor 76 is deenergized.
Upon completion of band switching operation, slide switch 66 is displaced toward the right, as viewed in FIGURE 1, to the band tuning position so that the operator may tune antenna 10. The operation of tuning antenna 10 is described in detail in my copending parent application, Ser. No. 327,713. Basically, the tuning operation is obtained by energizing a pair of motors located within housing 12, which motors serve to selectively extend and retract antenna elements 30 and 32. In the tuning operation the motors are energized so as to fully retract both of the antenna elements 30 and 32 so that an antenna length is defined which corresponds to a resonant frequency outside the high frequency end of the frequency band of the antenna. Radio frequency power is then applied to the antenna via the feed line 42 at a frequency near the high frequency end, but within the frequency band. The operator continuously monitors and measures the standing wave ratio (SWR) of the antenna 10 and of the feed line 42 by means of the SWR indicator 40. The reversible motors within housing 12 are then energized to simultaneously extend both antenna elements 30 and 32 until a minimum value of the standing wave ratio (SWR) is obtained. The impedance of the feed line 42 is then matched to that of the antenna 10 at the feed point by energizing the motors within housing 12 in a manner to alternately drive only one of the antenna elements 30 and 32 in opposing directions until it is established in which direction the antenna element must be driven to obtain an even smaller measurement of standing wave ratio (SWR). Thereafter, the selected antenna element is driven in that direction noted until the measurement of the value of the standing wave ratio (SWR) is at a minimum.
The invention has been described in connection with a particular preferred embodiment, but is not to be limited to same. Various modifications may be made without departing from the scope and spirit of the present invention as defined by the appended claims.
I claim:
1. A band switch assembly adapted for use with an antenna including an elongated conductive tubular element with an electrical feed point on one end and a tubular resonator coil assembly mounted at one end to the other end of said element in substantial coaxial relationship therewith, said band switch assembly comprising: a nonmagnetic electrically conductive forward stationary contact mounted in electrical contact with and extending outwardly from the coil of said assembly intermediate the ends thereof, a nonmagnetic electrically conductive rear stationary contact mounted in electrical contact withand extending outwardly from one end of said coil adjacent said element, and an elongated nonmagnetic electrically conductive member movable between retracted and extended positions and located exteriorly of said coil and said antenna a distance sufficient so as not to materially affect the magnetic field of the coil when energized, said member having a portion thereof in continuous electrical contact with said rear stationary contact and a forward portion thereof for electrical contact with said forward stationary contact when said member is in its fully extended position to thereby short circuit said portion of the coil between said rear stationary contact and said forward stationary contact.
2. A band switch assembly as set forth in claim 1 including motive means and nonconductive push rod means connecting said movable conductive member with said motive means for extending and retracting said member.
3. A band switch assembly as set forth in claim 2 wherein said motive means is a reversible electrical motor and motor control circuit means for reversing the operation of said motor for selectively extending and retracting said movable conductive member.
4. A band switch assembly as set forth in claim 3 wherein said motor control circuit means includes limit switch means responsive to the fully retracted and fully extended positions of said movable conductive member to de-energize said motor when said member is in its fully retracted or fully extended position.
5. A band switch assembly as set forth in claim 1 wherein said forward and rear stationary contacts take the form of sleeve members each having a pair of contact prongs which are resiliently biased radially inward for resiliently receiving said movable contact in frictional and electrical contact therewith.
6. A band switch assembly as set forth in claim 5 wherein the inner surface of said contact prongs and the outer surface of at least a portion of said movable conductive member are silver plated to insure a good elec- E2 trical contact between said prongs and said movable member.
7. A band switch assembly as set forth in claim 1, including a tubular element of electrically insulating and nonmagnetic material extending between and secured to said rear and forward stationary contacts, said movable contact being slidably received within said tubular element so as to be guided thereby in its movement between said forward and rear stationary contacts.
8. An antenna including an elongated conductive tubular element having an electrical feed point at one end, a tubular resonator coil assembly mounted at one end to the other end of said element in substantially coaxial relationship therewith, a band switch assembly mounted on said antenna including a nonmagnetic electrically conductive forward stationary contact mounted in electrical contact with the coil of said assembly intermediate the ends thereof, a nonmagnetic electrically conductive rear stationary contact mounted in electrical contact with one end of said coil adjacent said element, an elongated electrically conductive nonmagnetic shorting bar movable between retracted and extended positions, said shorting bar being located exteriorly of said coil and said antenna a distance sufficient so as to not materially affect the magnetic field of the coil when energized and having a portion thereof in continuous electrical contact with said rear stationary contact and a forward portion thereof for electrical contact with said forward stationary contact when said shorting bar is in its fully extended position to thereby short circuit said portion of the coil between said rear stationary contact and said forward stationary contact, a tubular element of electrically insulating and nonmagnetic material extending between and secured to said rear and said forward stationary contacts and receiving said movable contact therein to guide movement thereof between said stationary contacts, and said forward and rear stationary contacts being sleeve members each having a pair of contact prongs which are resiliently biased radially inward for resiliently receiving said movable contact in frictional and electrical contact therewith.
9. An antenna including an elongated conductive tubular element having an electrical feed point at one end, a tubular resonator coil assembly mounted at one end to the other end of said element in substantially coaxial relationship therewith, a movable antenna member movably secured to the other end of said assembly, a nonconductive rod like member extending longitudinally through said assembly and connected at one end to said antenna member for purposes of extending and retracting said antenna member to vary the overall length of the antenna, .a band switch assembly mounted onsaid antenna and including a forward stationary contact mounted in electrical contact with the coil of said assembly intermediate the ends thereof, a rear stationary contact mounted in electrical contact with one end of said coil adjacent said element, and an elongated electrically conductive shorting bar movable between retracted and extended positions, said shorting bar being located exteriorly of said coil a distance sufiicient so as to not materially affect the magnetic field of the coil when energized .and having a portion thereof in continuous electrical contact with said rear stationary contact and a forward portion thereof for electrical contact with said forward stationary contact when said shorting bar is in its fully extended position to thereby short circuit said portion of the coil between said rear stationary contact and said forward stationary contact.
10. An antenna as set forth in claim 9 wherein said movable shorting bar is movable independently of said movable antenna member.
11. An antenna comprising a housing, first and second coaxially aligned, elongated conductive antenna elements extending in opposing directions from said housing, each said element having a tubular resonator coil assembly mounted at its free end in substantial coaxial relationship therewith, each said resonator coil assembly having a movable antenna member movably secured to the free end of said assembly for varying the length of said antenna, means in said housing for independently extending and retracting each said extendable antenna member, a band switch assembly mounted on each said resonator coil assembly; each said band switch assembly including a forward stationary contact mounted in electrical contact with the coil of said assembly intermediate the ends thereof, a rear stationary contact mounted in electrical contact with one end of said coil adjacent said element and an elongated electrically conductive shorting bar movable between retracted and extended positions, said shorting bar being located exteriorly of said coil a distance sufficient so as to not materially affect the magnetic field 15 of the coil when energized and having a portion thereof in continuous electrical contact with said rear stationary contact and a forward portion thereof for electrical contact with said forward stationary contact when said shorting bar is in its fully extended position to thereby short circuit said portion of the coil between said rear stationary contact and said forward stationary contact.
12. An antenna as set forth in claim 11 including a nonconductive rod like member extending longitudinally through each said resonator assembly and connected at one end to one of said antenna members for purposes of extending and retracting said antenna member to vary the overall length of the antenna.
13. An antenna as set forth in claim 11 including reversible electric motor means and push rod means connecting each said shorting bar with said motor means to simultaneously extend or retract said shorting bars.
14. An antenna as set forth in claim 13 including motor control means for selectively energizing said reversible motor means to reversibly drive said shorting bars between their fully extended and fully retracted positions.
15. An antenna as set forth in claim 14 wherein said 10 motor control means includes limit switch means responsive to the fully retracted and fully extended positions of said shorting bars to de-energize said motor means When said shorting bars are in their fully retracted or fully extended positions.
References (Jited UNITED STATES PATENTS 1,945,735 2/1934 Davis 343750 2,719,920 10/1955 Ellis 343-750 2,854,667 9/1958 Taylor et a1. 343750 2,993,204 7/ 1961 Macalpine 343-861 X OTHER REFERENCES Najork: Slide Tuning The 75-Meter Loading Coil, Radio & Television News, January 1952, pages 52, 53.
ELI LIEBERMAN, Primary Examiner.

Claims (1)

1. A BAND SWITCH ASSEMBLY ADAPTED FOR USE WITH AN ANTENNA INCLUDING AN ELONGATED CONDUCTIVE TUBULAR ELEMENT WITH AN ELECTRICAL FEED POINT ON ONE END AND A TUBULAR RESONATOR COIL ASSEMBLY MOUNTED AT ONE END TO THE OTHER END OF SAID ELEMENT IN SUBSTANTIAL COAXIAL RELATIONSHIP THEREWITH, SAID BAND SWITCH ASSEMBLY COMPRISING: A NONMAGNETIC ELECTRICALLY CONDUCTIVE FORWARD STATIONARY CONTACT MOUNTED IN ELECTRICAL CONTACT WITH AND EXTENDING OUTWARDLY FROM THE COIL OF SAID ASSEMBLY INTERMEDIATE THE ENDS THEREOF, A NONMAGNETIC ELECTRICALLY CONDUCTIVE REAR STATIONARY CONTACT MOUNTED IN ELECTRICAL CONTACT WITH AND EXTENDING OUTWARDLY FROM ONE END OF SAID COIL ADJACENT SAID ELEMENT, AND AN ELONGATED NONMAGNETIC ELECTRICALLY CONDUCTIVE MEMBER MOVABLE BETWEEN RETRACTED AND EXTENDED POSITIONS AND LOCATED EXTERIORLY OF SAID COIL AND SAID ANTENNA A DISTANCE SUFFICIENT SO AS NOT TO MATERIALLY AFFECT THE MAGNETIC FIELD OF THE COIL WHEN ENERGIZED, SAID MEMBER HAVING A PORTION THEREOF IN CONTINUOUS ELECTRICAL CONTACT WITH SAID REAR STATIONARY CONTACT AND A FORWARD PORTION THEREOF FOR ELECTRICAL CONTACT WITH SAID FORWARD STATIONARY CONTACT WHEN SAID MEMBER IS IN ITS FULLY EXTENDED POSITION TO THEREBY SHORT CIRCUIT SAID PORTION OF THE COIL BETWEEN SAID REAR STATIONARY CONTACT AND SAID FORWARD STATIONARY CONTACT.
US379817A 1964-07-02 1964-07-02 Extensible dipole with adjustable loading coils Expired - Lifetime US3327311A (en)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1945735A (en) * 1930-07-24 1934-02-06 Wired Radio Inc Antenna compensator
US2719920A (en) * 1951-03-20 1955-10-04 Glenn R Ellis Multi-band mobile antenna loading coil
US2854667A (en) * 1956-02-24 1958-09-30 Zachary R Taylor Servo mobile antennas
US2993204A (en) * 1958-02-28 1961-07-18 Itt Two-band helical antenna

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1945735A (en) * 1930-07-24 1934-02-06 Wired Radio Inc Antenna compensator
US2719920A (en) * 1951-03-20 1955-10-04 Glenn R Ellis Multi-band mobile antenna loading coil
US2854667A (en) * 1956-02-24 1958-09-30 Zachary R Taylor Servo mobile antennas
US2993204A (en) * 1958-02-28 1961-07-18 Itt Two-band helical antenna

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