US2232693A

US2232693A - Antenna system

Info

Publication number: US2232693A
Application number: US131687A
Authority: US
Inventors: Jennings B Dow
Original assignee: Individual
Current assignee: Individual
Priority date: 1937-03-18
Filing date: 1937-03-18
Publication date: 1941-02-25
Anticipated expiration: 1958-02-25

Description

Feb. 25, 194-1. J ow I 2,232,693

ANTENNA SYSTEM Filed March 18, 1937 3 Sheets-Sheet 1 INVENTOR JENNINGS B. DOW

ay aw ATTORNEY Feb. 25, 1941. J. B. DOW

ANTENNA SYSTEM Filed March 18, 1957 s Sheets-Sheet 2 INVENTOR JENNINGS B. DOW

ATTORNEY Febyzs, 1941. J. B. DOW

ANTENNA SYSTEM Filed March 18, 1937 3Sheets-Sheet 3 INVENTOR JENNINGS B. DOW

ATTORNEY Patented Feb. 25, 1941' UNITED STATES ANTENNA SYSTEM Jennings B. Dow, United States Navy 7 Application March 18,

6 Claims.

1937, Serial No. 131,687

(Granted under the act of March 3, 1883, as

amended April 30,

My invention relates to antenna, systems in general but more particularly to an adjustable antenna system. 7

One of the objects of my invention is to provide an efilcient adjustable antenna for radio sending and receiving stations.

Another object of my invention is to provide a simple and inexpensive means for adjusting my antenna from a distance.

A still further object of my invention is to provide a simple combination of transmitter (or receiver), transmission line and adjustable anterms. to produce a highly efficient system as a whole. Other and further objects of my invention will be apparent from the specification. The present invention is generically similar to that covered by my copending application Serial Number 131,686, filed March 18, 1937.

For simplicity, my invention will be described with particular reference to its use for radio transmission. This simplification is not intended to restrict its scope, since it is equally applicable to receiving systems. Moreover, while the transmission lines which I shall describe in the preferred embodiment of my invention, are of the concentric type, it will be understood that any other suitable type of line may be used. For example, an open type line may be employed by making one or both conductors in tubular form for supplying gas pressure to operate the antenna.

Fig. 1 shows one form of my adjustable antenna in which the adjustable radiator element is in efiect a continuation of the inner conductor of a concentric transmission line.

Figs. 1a and 1b are cross sections taken on lines a--a and b-b, respectively, Fig. 1.

Fig, 2 shows another form of my antenna in which the adjustable radiator element is a continuation of the inner conductor of one section of a concentric transmission line which is connected to a second matched section of line of smaller diameter. The matching is accomplished by appropriate design of the two sections of line.

Fig. 2a is a cross section on the line a-a, Fig. 2.

Fig. 3 shows another form which my system may take.

Fig. '3a is a cross section on the line a--a, Fig. 3.

Fig. 4 shows a still .tion.

further form of my inven- Fig; 5 shows schematically a system for operating the antenna by gas under pressure.

Fig. 6 illustrates a metal piston operating in an insulating cylinder, which is physically a prolongation of the outer conductor.

In Figs. 1, 2 and 3 adjustment of the radiator is accomplished by variation of gas pressure in the transmission line so as tormove a piston which is fixed to the radiator element. In Fig. 4 a gas pressure operated motor turns a screw which in turn moves the radiator to the desired position.

Fig. 5 shows one form which the input end of the transmission line may take in supplying electrical energy and gas pressure to the antennas of Figs. 1 and 2.

In Fig. 1 I show a movable tubular radiator element I having aflixed at one end a piston 2 of electrical insulating materialhaving packing rings 3 which wipe the inside surface of the outer conductor 4 of a concentric transmission line 4-5 having an inner conductor 5.

Radiator I slides freely over the inner conductor 5 of the transmission line. The transmission line is terminated physically with an insulating spacing member 6 having a packing ring 1 for keeping out water. Pressure ,of gas applied between the inner and outer conductors of transmission line 4-5 moves radiator I and piston 2 against helical spring 8 which serves to lower the radiator element I when the gas pressure is reduced. Spring loaded valve 9 may be provided to maintain atmospheric pressure in the spaces above piston 2, although this is not essential since the gas in these spaces may be compressed or expanded according to the position of the piston 2.

Fig. 6 shows an alternative form of construction in which the outer conductor la of transmission line la-5a is terminated in a cylinder of insulating material in which the piston 2a oper-. ates. Such construction makes it possible to use a metallic piston 2a in lieu of the insulated piston 2 required in Fig. 1.

The radiating portion of this form of antenna is that which extends beyond the outer conductor of the transmission line. Thus, in Fig. 1, dimension X represents the length of the radiating portion, whereas dimension Y in Fig. 6 gives the length of the radiator.

In order that the electrical load resistance represented by the radiator will be of the correct value so that reflection of electrical energy will not take place at the junction of the radiator and transmission line, it is essential that the.

antenna or radiator resistance be matched with that of the line. The characteristic impedance of a transmission line operated at the high frequencies employed in radio is in the nature of a resistance. To efiiciently match a radiator to such a line without recourse to auxiliary apparatus, requires that a resonant radiator be employed. In that form of my invention shown in Figs. 1 and 6, proper impedance matching requires that the length of the radiator be an odd number of quarter wave lengths. As the length of the radiator becomes a critical function of frequency for a proper match to the line, close adjustment of radiator length is required. As my system is of the continuously variable type and capable of close adjustment to any length within designed limits, and as this adjustment can be made from a distance with little auxiliary apparatus it has advantages not known to exist in prior systems.

Fig. 2 shows another form of my invention in which the radiator element I I is operated against the tension of spring I2 by gas pressure applied to the inside of inner conductor I3 of transmission line l3!4. Transmission line I3I4 is terminated physically at both ends by gas tight insulating members I5 and I6. At I1 is shown a spacing insulator for concentric line I3--I l. Packing rings are shown at I8 to prevent the escape of gas.

A second section of concentric transmission line is' shown having inner conductor I9 and outer conductor 2!]. The outside diameters of inner conductors I3 and I9 are so proportioned to the inner diameters of the outer conductors I 4 and 20 that the characteristic impedances of the two sections of line are equal. Spacing between the two connecting conductors 2I and 22 is also determined to yield this same characteristic impedance in order that electrical reflections at this junction will be a minimum.

Gas pressure for raising and lowering radiator II is applied through the space between conductors I9 and 2G, thence through channel 23 in insulator I8 to the inside of tubular conductor I3.

At Fig. 2a is shown a sectional view showing ground plane conductors 24 which take the form of wires extending from the upper end of conductor M.

Fig. 3 shows another form which my antenna may take. This comprises a metallic cylinder 25 mounted upon an insulator 26. A movable conductor 2? having a piston 28 with piston rings 29 in combination with cylinder 25 and that portion 3% of concentric transmission line 3Il3I which extends above the outer conductor 3| of the transmission line, comprise the radiating portion of the system.

In that form of my invention shown in Fig. 3, I move the rod 21 up or down by applying gas pressure to both sides of piston 28. Conductor 30 of the transmission line is of hollow tubular construction for applying pressure to the lower side of piston 28. Pressure is also applied through the space between conductors 3i] and 3|, thence through electrically insulating tube 32 to. the upper end of cylinder 25. In this manner, piston 28 and rod 21 may be adjusted to any desired position. A stuffing box 33 at the upper end of cylinder 25 prevents leakage of gas.

In Fig. 4 is shown a still further modified form of my invention having a concentric transmission 1ine3 .35 with a hollow inner conductor 34- and tubular out-en conductor 35 for applying gas through either tube to a turbine engine device having a fixed nozzle disc 3i: of insulating material affixed to the outer conductor 35 of transmission line 34-35. The rotary portion of the turbine comprises rotor 31 of insulating material affixed to the hollow shaft 38 and screw 39 which engages the radiating member 43 for raising or lowering same to the desired position. The remaining portion of the system comprises ports All in shaft 38 and thrust block 42 of insulating material which also acts as a transmission line spacer.

The turbine Its-3'! is of the reversible type to permit rotation in either direction according to which direction the gas pressure is applied. It will be understood that the turbine may be located outside the transmission line and may take any suitable form of construction. Moreover, it may be replaced by a reciprocating engine device without departing from the spirit of my invention.

At 43 is an insulating member of appropriate construction for sealing the system against the entrance of moisture or escape of gas at that point. The radiator it has a conductive connection through screw 39 and shaft 38 to the inner conductor 34 of transmission line 3-t35. In antenna systems of this type, the radiating portion is that conducting part which extends in space above the other or outer conductor of the transmission line, as previously mentioned.

Fig. 5 shows the output portion of the final stage of a radio transmitter 44 having an amplifying tube 45 the anode 46 of which is connected to an output circuit ii-48 to a high voitage source it through a current indicating device The output circuit is coupled or connected to the inner conductor 55 of concentric transmission line til-52. Outer conductor 52 is shown grounded at 53.

Transmission line 5I52 is sealed gas tight by an insulating device 54. Means are provided by valve 35 for admitting gas from tank 59 to the transmission line 5I52 for varying the pressure in the line to adjust the height of the antennas of Figs. 1 and 2. Pressure indicating means 56 may be calibrated in terms of antenna height. Final adjustment of antenna height is most effectively accomplished by noting the reading of current indicating device as the length of the antenna is changed. An alternative source of gas is shown by pipe connection 5! through valve 58.

I have found it desirable to use dry compressed nitrogen or carbon dioxide as a gas. Any dry gas or even an insulating liquid may be employed if desired. The term fluid will be understood to apply to any suitable gas or liquid.

If it is desired to employ an open type of transmission line in lieu of a concentric line, one or more conductors of the line may be made of tubular construction for applying the gas pressure.

While I have described my invention in certain preferred embodiments, it will be understood that 'modificatiohs may be made, and that no limitations are intended other than those imposed by the scope of the appended claims.

The invention herein described and claimed may be used and/or manufactured by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

What I claim as new and desire to secure by Letters Patent in the United States is as follows:

1. An antenna system including a high frequency transmission line having two concentric conductors at least one of which is tubular, a radiating element mounted in, electrically connected to and projecting from said tubular conductor to transfer electric currents between said tubular conductor and said element, said element being sufliciently rigid to be self-supporting and free at its outer end and arranged to slide in said conductor; in a fluid-tight manner, and means for applying fluid pressure to said tubular conductor whereby the effective length of said radiating element may be adjusted to selected values to respond efi'iciently to different Wave lengths.

2. An antenna system including a concentric high frequency transmission line having a tubular outer member, a radiating element projecting from and mounted in said tubular member and electrically connected thereto to transfer electric currents between said tubular member and said element, said element being sufficiently rigid to be self-supporting and free at its outer end and arranged to slide in said member in a fluid-tight manner, and means for applying fluid pressure to said tubular member whereby the effective length of said radiating element may be adjusted to selected values to respond to different wave lengths.

tight manner, and means for supplying fluid pressure to said tubular conductor wherein said element is mounted to change the effective length of said element to selected values to respond efiiciently to different wave lengths.

4. An antenna system including a high frequency transmission line having at least one tubular conductor, a source of gas under pressure having a gas connection to said tubular condoctor, an (antenna element projecting from said tubular conductor, a screw engaging said antenna element and means for turning said screw, said means comprising a gas driven engine device contained within said tubular conductor whereby the eflective impedance of said antenna element may be adjusted to a value substantially equal to the surge impedance of said transmission line.

5. An antenna system comprising a high frequency transmission line having at least one tubular conductor, a! tubular radiating element projecting irom said tubular conductor, said element being free at its outer end and sufficiently rigid to be self-supporting, a motor drive for adjusting the length of said radiating element and remotely controllable means for supplying power axially through said tubular conductor to operate said motor drive.

6. An antenna system comprising a high frequency transmission line having at least one hollow conductor, a tubular radiating element projecting from said hollow conductor, said element being free at its outer end and sufficiently rigid to be self-supporting, a motor drive for varying the length of said radiating element, said motor drive beng wholly'conta-ined within said hollow conductor, and remotely controllable means for supplying power longitudinally through said hollow conductor to operate said motor drive.

JENNINGS B. DOW.