US2602895A - Ultrahigh-frequency antenna apparatus - Google Patents

Description

y 1952 w. w. HANSEN 2,602,895

4 ULTRAHIGH-FREQUENCY ANTENNA APPARATUS Original Filed Jan. 16,1942 3 Sheets-Sheet 1 5 COMMUTA m/z Ill 186 "mm/5m: r7512 173 INVENTOR WILLIAM W. HANSEN E E/KM ATTORN EY July 8, 1952 w. w. HANSEN 2,602,895

ULTRAHIGH-FREQUENCY ANTENNA APPARATUS Original Filed Jan. 16, 1942 v 5 Sheets-Sheet 2 J92 OUTPUT T0 RECEIVER INVENTOR ATTO RNEY y 1952 w. w. HANSEN 2,602,895

' ULTRAHIGH-FREQUENCY ANTENNA APPARATUS Original Filed Jan. 16, 1942 s Sheets-Sheet s INVENTOR ATTORNEY Patented July 8, 1 952 ULTRAHIGH-FRE QUENCY ANTENNA APPARATUS William W. Hansen, Stanford University, Calif.,

assignor to The Sperry Corporation, a corporation of Delaware Application May 1, 1943, Serial No. 485,554, now Patent No. 2,500,178, dated March 14, 1950, which is a division of application Serial No. 426,986, January 16, 1942, now Patent No. 2,468,751, dated May 3, 1949. Divided and this application April 25, 1946, Serial No. 664,764

6 Claims. (01. 25033.65)

I The present invention relates to novel antenna apparatus operable at ultra-high and super-high frequencies, and to commutator means operable at such frequencies. This invention relates, more particularly, to directional. antenna apparatus adapted to produce overlapping highly directional radiation or receptivity patterns, such as are useful in radio location of distant objects, radio guidance and navigation, and radio direction-finding. I r

The present application is a division of application Serial No. 485,554, filed May 1, 1943, now Patent No. 2,500,178, issued March 14, 1950, which is itself a division of application Serial No. 426,986, filed January 16, 1942, now Patent No. 2,468,751, issued May 3, 1949. These applications disclose systems wherein the present invention may be utilized.

An object of the present .invention is to provide an antenna system wherein, in operation, alternate and overlapping directive beams may be produced. 7 v

A still further object of this invention is to provide radiating or receiving wave-guides toether with control means adapted to vary the phase velocity of the electromagnetic waves within said Wave-guides at will.

v A further object is-to; provide a cylindrical parabolic reflector; with, a ,pair of: antennae located'oneither sideQi the focus thereof and meansto increase theinterchange of; energy be.-

tween the antennae'and the refiector'so that substantially all the energyisj directed by. the reflector-whose radiation, pattern is. shifted by alternately energizing said antennae.

Other objects and advantages-will become apparent from thev specification, taken. in connection with the accompanying drawings wherein the invention is embodied in concrete form.

In the drawings, v

Fig. 1 is an elevation view ofan antenna array, including a transmitting antenna, an azimuth receiving antenna and anelevation receiving antenna, according to the present invention Fig. 2 is a cross-sectional View of the elevation 2 capacitance-changer of Figs. 5 and 6, in two difierent positions.

Figs. 9 and 10 are idealized elevation and azimuth views of the radiation patterns of the azimuth antenna of Fig. 1.

Fig. 11 is a longitudinal elevational view partly in cross-section of another form of the present invention, not requiring separate commutating means. V a

Figs. 12 and 13 are sectional views of oneform of wave guide phase'velocity modulating rods useful in Fig. 1'1. h 1 Figs. 14 and 15 are sectional views of another form of wave guide phase velocity modulating rods useful in an arrangement similarto Fig. 11. Similar characters of reference are usedin all of the above figures to indicate corresponding parts.

In prior parent applications, Serial Nos. 485,554 and 426,986, there are disclosed 'several'systems for radio-location of objects using overlapping, alternate, highly, directive ra-canon or receptivity patterns. The present invention is directed more specifically toward novel antenna and switching apparatus for producingsuch' patterns. One form of such apparatus isshown in Figs. 1-10, wherein is illustrated a receiving system for receiving energy froma distant point, either by reflection from an object atsuch point or by radiation from a transmitter there. Fig. 1 illustrates a system of the former type, where radiant energy derived from a transmitter I0! is supplied to a'radiatorlZ placed at the 'focus of a'cylindrical parabolic reflector [82,.forming a space-radiation pattern thatis substantially fan-shaped, being sharply directivein' azimuth and broadly directive in elevation. Energyfrom radiator 12 is reflected by a distant object'to be located and is then received by receiving antennae I3, I 3.

Receiving antennae l 3, and t3, placed on either side of the focus of a cylindrical parabolic refiector 183, form partially overlapping receptive antenna of Fig. L't'aken along line 2-2 thereof.

Fig. 3 is a fragmentary cross-sectional view of Fig. 2, along line 3-3 thereof. a g V Fig. 4 is a plan view of the commutator shown inFig.1. If} r f Fig. 5 is a plan view incross-Ys'ection of a portion of Fig.4. j 5

Fig. .6 is a cross-sectioiibf Fig. '5 along line 6-6 thereof/f l I Figs. '7- "andB-ai fragmentary views of the spatial patterns that T are substantially fanshaped. Each of these patternsis similar to the radiation pattern from transmitting antenna I2, being sharply directive in azimuth and broadly directive in elevation. The axes of symmetry of the principal receptive lobes are equi-angularly displaced to either side of the azimuth axis of the locating system so thatthegain characteristics of the antennae l3 and [3 are equal along this azimuth axis. Fig. 9 and Fig; 10 illustrate diagrammatically these partially overlapping spatial patterns. Principal lobe [60,having an axis of symmetry 3M, is associated-with, say, :antenna 13, and lobe I61, having an-axis302, is associated with antenna I3. muth axis .of the locating system and it will be seen to correspond an equi-signalpath.

Receiving devices I3 and I3 feed the incoming energy through concentric lines I26 and I21, respectively (Fig. 4), to suitable energy control means shown as having the form of an ultrahigh-frequency commutator I6. Commutator I6, driven by the shaft I44 of a motor I5, alternately connects lines 126 and I21 to an output line I1, switching inputs at a suitable frequency. This commutator is illustrated in Figs. 4-8. This device, utilizing the properties of quarter-wavelength lines, causes the output impedances of coaxial lines 'IZS and I21 to alternate between low and substantially infinite values. This is accomplished by connecting quarter-wavelength lines to the coaxial cables I26 and I21, respectively, these coupling lines being terminated at their free ends by variable impedances rotated by the motor I5. The frequencies thus commutated are supplied-through the output coaxial line I1 to the'receiver described in detail in the above-mentioned parent applications, or to any other utilization device.

Receiving antennae andI 4', placed on either side of the focus of tr-cylindrical parobolic reflector I84, asshown in Fig. l, are identical to antennae I3 and I3 and reflector I83, respectively, except thatthe former 'are arranged to be sharply directive in-elevation while the latter are sharply directive in azimuth. Receiving devices I4 and 4'4 for the vertical plane feed through lines I91'and I96, respectively, to an ultra-high frequency commutator 38 similar to the device I6 and-switched synchronously therewith by the motorshaft I44. The commutator 30 is connected by a suitable coaxial line 3| to a similar receiver, as described in said-parent applications.

Fig. 1 shows the physical arrangement of the antennae. Wheels I10 support a platform I1I upon which restsa rotatable pedestal I12 bearing'a yoke I13. Anfannular gear I14 fastened to the pedestal I12eng'ages a worm gear I59 on the axleof the motor 56. The motor is fastened to the yoke 'I13by'abrac'ket I15. The arrays are mountedas a unit between'the arms of the yoke I13 on a left trunnion I16 and a right trunnion I11. The trunnion I11 passes through the yoke and serves as a'shaftfcr'a'gear I18'wh'ich engages a worm gear I19 on the axleof the motor 5I. As described in saidparentapplications,the receiver may contain suitable circuits ref automatically controlling motors 50, 5| to 'fnaintain'the antenna array directed. at a desired distant object, or, alternatively, motors 50 and 5| may be manually controlled to orient the antenna array by hand, to sweep the sky in any desired manner.

Thear'rays consist'of similar reflectors I82 and I83. placed side by side containing the transmitting radiator I2 and the receiving antennae I3 and I3, respectively as Well as the reflector I84, rotated 90 in the plane of the figure with respect to the reflectors I82 and I83, containing the receiving antennae I4 and I4. The reflectors I82, I83 and I84, strengthened by braces I86, are held by a frame I85. The openings of the reflectors are narrow rectangles while the section at right angles to the plane of Fig. 1 is parabolic as is shown in Fig. 2.: The reflectors are, therefore, highly directive in the plane of Fig. 2 and broadly directive at right angles to this plane. The antennae I4 and I4 are displaced, preferably, one-eighth'wavelength toeitherside of the A line 300 represents the aziimpedance-transforming focus of the reflector I86 on the latus rectum of the parabola. The antennaezlfi and I3 are similarly located, The efl'ectis to produce directive spatial patterns whose axes of symmetry are not parallel to the principal axis of the parabola. The patterns shift, as shown in Figs. 9 and 10, when first one antenna and then the other is activated by the commutator of Figs. 4-8. Truncated cones I93 and I92, shown in section by Fig. 3, facilitate the interchange of energy between the antennae I4 and I4 and the reflector I86. Segments are cut from the portions of these truncated cones that face the mouth of the reflector, as shown most clearly in Fig. 2. The sides of these slices are bounded by planes drawn from the focus of the cylindrical parabolic reflector to its outer edges at right angles to the reflector's fiat surfaces. A cylindrical arc concentric with the focus bounds the inner faces of the cut-away parts. This design is to reduce direct radiation from the antennae (which would spread over a wide angle) and to restrict it to the reflected beam.

Fig. 3 shows two concentric lines with inner conductors I94 and I95 and outer conductors I96 and I91, respectively. A dielectric I98 may fill the space between the inner and outer conductors. The conductors I94 and I95 merge with the upper truncated conducting cone I93 while the conductors I96 and I91 unfold into the lower cone I92. In the space between the cones the conductors I94 and I95 are unshielded and, consequently, become the radiators I4 and I4, respectively. The concentric lines, similar to or connected to lines I26 and I21 in Fig. 4, may be adjusted in length at the commutator IE to make one radiator have a substantially infinite input impedance when the other radiator is energized, and vice versa. Under these conditions the inactive antenna does not absorb radiated energy. The devices in Figs. 1-3 may be interchangeably used for either reception or radiation, by reason of the reciprocity theorem.

Referring now to Fig. 4. there is shown the commutator I6 of Fig. 1. Concentric line I26 from antenna I3 connects to a line I22 through the horizontal branches of a cross-shaped adjustable coupling or junction device I24, illustrated in Fig. 5 in greater detail. In a similar way the concentric line I21 from'antenna I3 connects to a line I23 through the horizontal branches of a cross-shaped adjustable coupling or junction device 'I25, similar toI24. Lines I22 and I23 join to form the coaxial cable I1 which feeds the receiver. Vertical stubs I62, I03 of the couplings I24 and I25, projecting above the junction with the horizontal branches, contain adjustable shorting plugs I28 and I29, respectively. Vertical sections extending below the crossing adjustably attach to lines I3I and I32, which latter issue from shielding boxes I33 and I34, respectively. Shafts I M and I42, having attached pinions I31 and I38, respectively, project from the shielding boxes I33 and I34, respectively. Gears I39 and I40 on a shaft I36 mesh with pinions I31 and I38, respectively. A gear I43 on the shaft I '44 of the motor I5 engages the gear I40, and consequently the shafts MI and I42 through their associated gearing are rotated synchronously with the motor I5. Coupling I24, line I3I, box I33, shaft MI, and gear I31 are designed to be horizontallydisplac'eable as a unit for a distance of one wavelength at the operating carrier frequency, for tuning purposes, as is the combination of coupling I25, line I32, box I34yshaft142and gear I38. The

pinions I37,- .and.=; have e hs. de u to allow for these displacements. The junctions oi devices I24 and I25 may also be vertically ad: j sted by m an .oI t e s id hl t ac m b we n t l e e tlcalar sof, these evice and coaxial lines l3 I and I32,,respectively,,to a er t eir d e to the h d n b xe I 3 a d J P Q Y- Fi 5 is a detailedsectionalview of the' left poro pf .F erevealing th mfl Qd. m mma h c a l lines o Junc o device I?! a th in: er o ar me of thc i i hi 3- Th inner QI S I2 3; '25 and 50i 6.90- axial lines I22, I25, andISI. respectively, arehollow andoisuch an interior diameter as to permit the two horizontal and lower vertical inner 0on ductors I24 of the junction deviceiifl to slide r n. ,T ssi o lines 26 anal?! a e l issi' la fi. ea l w. he e ri r h junction device I24 tofslide therein, lnsulatin washers l l5,.and I41 suppert theinnergcohduc tors I24 coaxial with the exterior of device l2'4. An insulating washer 148 supports the inner conductor I3I. 'withinfline I31. The ratio of the outside diameter of'conductors I24 tothe in-. side diameter oi the exterior conductor of junction device I24 is madesubstantially equal to the ratio of the outside diameter of conductors I22. I26 and I3I' to the inside diameter of their respective exterior conductors, to'maintain the characteristic impedances' of the various sections equal. The shorting plug I28 is madet'with 'aholw: "bore to facilitate longitudinal adjustment within the uprightstub. of junction device I24. Theho'nductbr [3J5 vprojetsinto the shielding box I33 where i'condenserplate 149' is fixed to its end. The planview of a preferredform of the plate I49 is shown'in Figs? and 8. The

other plateof. the'condenser may be considered:

the adjacent grounded side of theshielding box I33. The coaxial line ,I 3 Iland the section of junc' tion' device I24 "below the junction point,"there fore, is terminatedibya apacitance'fwhose mag. nitude depends'b'n' the aofthf'e platel maria the spacmgfand dielectric constant between thev plate I49 andthesid'of the box' I332. The shaft; MI, driven 'byjthe' motor .I5through 'the gears I31, I39, shaitI36, gears I40, I43 and shaftil44,

as mentioned above, rotates in ball-bearings I5I andspins a double-bladed chopper I52 between the plate I43 and side of the box I33. Chopper I52 is roughly analogous to a light chopper used in motion picture art. Fig. 5 shows one of the blades of the chopper I52 meshed as in Fig. 8. Fig. 6 is an alternate view of the "box I33 taken at right angles to the plane of Fig. 5 looking from the base of the box at the end of the conductor I3I'. r a

The chopper I52 may beconstructed of a highdielectric-constant, low-loss, non-conductor. or

may be made of a conductor which is insulated I from the shaft I4I. The eifect of a non-conductor is to increase the capacitance whenmeshed with plate I49 because the dielectric constant-of the interveningspaceis increased. The'effect of an insulated conductor is to createtwo condensers in series which have increased'capacitance due to the reduced air gaps, the series combination being greater in capacitance than the capacitance in the open position. The shielding box I33 is dimensioned to be non-resonant to the transmitter frequency. 7

The operational alignment of the commutator I6 of Fig. 4 is simplified by utilizing the teachin of the reciprocity theorem which allows the substitution .:--of an. ultra-,high fr quencyv 0501]: later in place. of the receiveron the end of the coaxial line I I, to provide atemporary local power source. The alignment (whichisundisturbed by this substitution) may be performed by the following stepsz; I

First, mesh theleft-hand chopper I52 as in Fig. 8 and adjust the length of the line from the plate I49 to the junction point of the junction device I24 until no energyfiows down the left line I26 tothe radiator I3.- This means there an effective .short at the center of the junction device I24. 1 r y I I Repeat this adjustment for the rlght hand side Q e- Next, unmesh theleft-hand chopper I52 as in Fig. 7 and adjust. the plug I28 in the stub of thecoupling J24 untilthere are no standing waves in theline I22. .This means there is no reflection from the junction point of the junction device I24, and energy may flow unimpeded to the left radiator I3.

r Repeat thisadjustment ion the right side of Figi a I.

Adjust the length ofcoaxial line I26 to the antenna I3 with the chopper-152T meshed until the line has no field present;indicating that the inactive antenna" I3 is absorbing no energy radiated by the active ant na I3: This means that when the junction; point of coupling 1 I 24 is efiectively shorted, theiantenna'end of the line I26 is made to appear as an open circuit, and there is no loss of radiatedpowerfrom the energized antennaI3'. 5 "f 1' 1 Repeat this adjustment for the right-hand lineIZ'I. r I;

These above steps-"are repeated until the alignment conditions are satisfied. The-purpose of the stub line on coupling I24 is to couple a conjugate impedance to the junction point of coupling I 24 which will compensate for the fact that the "chopper I52- producesonly a-finite change ofcapacity. I f

Bysuch a commutating arrangement as has just been described, 'the radiators are alternately efiective, each being active substantially half of the time and inactive during-the period of the others activity. Sinusoidal switching may be employed for mechanical simplicityalthough the total radiation is reduced. The utilizationof the former method causes the beam shown in Figs. 9 and 10 to jump alternately between the smoothline 7 position and the I dashed-line positionywhile the latter method shifts the beam smoothly from one position to the other. 7

Figs. 11-15 illustratea method of obtaining the necessary oscillating beam without resorting tothe commutator oi -Figs l-fi. Referring to Fig. 11, a radiator 225 is located at the junction of wave guide branches 225 and 22'! shown in longitudinal section. Flat conducting rods 228 and 229, extending the length 01' the branches, are equipped with trunnions on their ends to permit free rotation in supports 230 and 23I. re-

spectively. Figs.' 1'-2 -and 13 show in section the positions of reds- :25am: 229, respectively. -A drive .shaft 232, seen in-section, impels a driver 233 of aGfneva movemenewhich is engaged to adriven wheel 234. A shaft'236, seen in section, connects the wheel 234 to a bevel gear 231 as well as extending beyond-the plane of the paper to actuate a-second' wave guide-Tor the other space coordinate. I The gear 231 meshes with a gear 236 on 'a shatt239. The rod 229 is driven by the shaft 239 through bevel gears 243 while the rod- 228 is seventy this shaft through gears 242, 244 and 245 on shafts 240 and 24!.

In operationthe rods 228 and 229 intermittently and alternately occupy the positions in the wave guides'shown in 'Figs-.'12"and 13. Altering the position modifie's' theeifective cross-section which results in a 'change 'o'f the phase velocity of propagationwithin'the'wave guide branches,

The direction-of propagation of the radiated waves in free space forms an angle with their direction inth'e hollow wave guide whose cosine is'the ratio, o f the 'phasefvelocity of the'waves in free space to that 'of the phase velocity of the waves in saidguide. Since; the phase velocity of propagation in) free space is constant, the direction of free space propagation must shift according to this c'osine lawrelating phase velocities and directionsofpropagation within and without the radiating guide. g

The rods in Fig. 1| may be 'driven smoothly without the use of the Geneva movement. In this case the mechanical'simplification'may compensate for reduced electrical sensitivity.

An aiterhatef'typejoffrod is'shown'in Figs. 14 and 15; 'correspondingftoFigs; iza'nd 13. Conducting rod'sf250 ancff25l fhaltffound in section,

alternately fitj nto: cavities'of' wave guides 252' and 253, respectivelyl ."Here' i the cross-sectional area is actually reduced, whereas inFigs. 12' and 13 the effect is .dueto field distortion. 1 d i Since many changes fcou'ldfb e made in the above constructionand many apparently widely different embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the abovedescription or shown in the accompanying drawings shall .be interpreted as illustrative and'not in; a limiting sense.

Whatisclaimed is: v 1. High frequency: apparatus comprising a conductive parabolic reflector, a pair of parallel conductive walls having parabolically curved edges joined to said parabolic reflector, antenna means placedon eitherside of thefocus of said reflector and between ,said walls, cone-shaped energy translating means associatedwvith said. antenna meansionincreasing the interchange of energy between said antenna means and said reflector, the bases: of said cone-shaped means being in contact with said walls, said reflectori producingpartially;overlapping radiation patterns, the axespo f symmetry 'of'saidpatterns,

8 conductive i1 walls havingparabolically curved junctions to 5 said parabolic reflector, antenna means-plac'ed substantially at the focus of said reflector, ar-id f conductive cone-shaped energy translating xneans-associated with said antenna means for increasing the interchange of energy between saidantenna'and reflector means, said cone-shaped energy translating means comprising a pair-of cones oppositely directed along a commonaxis and-having their bases in contact with the-respective ones of said conductive walls.

3. High -freduencyfantenna apparatus comprising two "conducting radiating wave guides forming a predetermined angle with respect to eachother, means for launching v electromagnetic waves of i s'ubsit'antiaily "linear polarization for traveling along said flguides, *conducting rods within and", extendingjalong said guides, said rods being turn'able around their longitudinal ax'es for' alteiing-th-phasevelocities of said waves within said guides, said guides having distributedradiating-means extending along the length of'the same at right ang'les to the electric vectorof said waves for propagation of said waves ,inspacefithe direction of said propagation'being ShlftedfiS the-phase velocities'oi said waves within sai'd gulides are altered by said turnablerods'.

4. I-Iigh'fr'equency antenna apparatus as defined in claim 3, further including means intercoupling said'rods 'for maintaining a predetermined relationibetween the angular positions thereof, cne of said rods being at the angular position*formaximumwave guide phase velocity when the other-of sai'd' rods is'in the position for minimum wave guide "phase velocity.

' 5; Ultra 'highirequency apparatus comprising-a hollow wave guide and an axially extending rotatable memberftherein for varying the phasevelocity'or waves propagated along said guide, said member being eccentricaily mounted whereby itsj positim relative'tothe walls of said guide; is varied upon rotation'thereof.

"6; llltra high frequency' 'apparatus comprising a hollow wave guide and .anaxiaily extending-rotatable' m'ember jth'erein for varying the phase velocity 01"Wa'ves propagated along said guide,'said memberjhaving 'a non-circular crosssection. MW.HANSEN.

- EFERENCES CITED he followingreferences a .of record in the ;UNr rED .sTA'rns PATENTS -Australia Dec. 9, 1941

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