US2519209A

US2519209A - Antenna

Info

Publication number: US2519209A
Application number: US585662A
Authority: US
Inventors: Harold A Wheeler
Original assignee: Hazeltine Research Inc
Current assignee: Hazeltine Research Inc
Priority date: 1945-03-30
Filing date: 1945-03-30
Publication date: 1950-08-15
Anticipated expiration: 1967-08-15
Also published as: GB609993A

Description

Aug. 15, 1950 H. A. WHEELER ANTENNA 2 Sheets-Sheet 1 lill. "i

,z` INVENTOR.

HAROLD A. WHEELER ATTORNEY Filed March 30, 1945 n om i.: Mm- NN om mw u E P F PE E. 1 www H mN ww -f L o. .f H mL. TI. w .E

Patented Aug. l5,b 1950 HaroldA A. Wheeler, Great Neck, N. Y., assigner, by mesne assignments, to Hazeltine Research, Incl, Chicago, Ill., a corporation of Illinois Application March 30, 1945, Serial No. 585,662'

(Cl. 250W-33).

Claims. 1

This invention relates, in general, to antennas and is particularly directed to antennas for operation over a Wide range of wave lengths.

One antenna of the prior art designed for andeband operation, comprises a biconical radiator of circular cross section throughout and having a length equal to one-half the mean wave length of its operating range. This priorY art arrangement has been found to be operative, but has a limited practical value in view of the diillculties encountered in fabricating biconical elements to specic dimensions. Such prior arrangements also have a very appreciable thickness Vwhich limits their use in connection with high-speed airplanes and the like.

It isv an object oi' the present invention, therefore, to provide an antenna, which substantially avoids the above-mentioned limitations of the prior art arrangements.

It is another object of the invention to provide an antenna of simplied and inexpensive construction and adapted for operation over a Wide range of Wave lengths.

It is a, specic object of the invention to provide an antenna having substantially the same impedance and radiation characteristics as the above-described biconical antenna but of simplified and inexpensive construction.

In accordance with the invention, an antenna for operation over a Wide range of wave lengths comprises an elongated conductive sheet of dlamond shape having a length approximately equal to one-half the mean Wave length of its operating range and a maximum thickness which 1s much less than its greatest width.

For a better understanding of the present 1nvention, together with other and further objects thereof, reference is had to the following description taken in connection with the accompanying drawings, and its scope will be pointed out in the appended claims.

Fig. 1 is a cross-sectional view of a, stacked antenna arrangement including an elemental antenna constructed in accordance with the pres.- ent invention; Fig. 2 is a plan view of an elemental antenna of the assembly of Fig. l; Fig. 3 is a sectional view taken as indicated by direction arrows 3-3 of Fig. l;v Fig. 4 is a cross-sectional view of a modined antenna arrangement in accordance with the inventonyl'ig. 5 is a furtherA cross-sectional View taken as indicated by direction arrows 5-5 oi Fig. 4.; Fig. 6 is a schematic representation of a, V-type antenna, While Fig. 7 represents a loop antenna, each of which embodies the present invention.v

Referring nowY more particularly to Figi', the antenna arrangement there represented includes stacked antenna' or radiator elements, dening `a pair of dipole antennas arranged in backfto back relationship'. The assembly includes four radiating elements I0, II, I2 and I3, individually comprising an elongated conductor of diamond shape illustrated in Fig. 2. The length Z of each such element is approximately equal to' one-half the mean Wave length of the operating range of wave lengths of the antenna.v The expression approximately equal to one-half is intended, for best operation, to include the range `from three-eighths to live-eiglfits.V The maximum WidthwV is approximately equal to one-third the length, being between one-quarterand one-half the length for best operation. The maximum thickness t is much less than the greatest Width, usually being less than one-half thereof. VPref-- erably, the conductoris stamped from a brass strip of uniform thickness.

Radiating elements I0 and Il are 'coplanar and are aligned in eneide-"end relationship 'on one side of a conduit Ill of rectangular-'cross section, While elements 'l2 and i3 are'similarly arranged on the opposite side of the conduit. To this end, each of the radiating elements .is supported by a conductive post I having a length approximately equal to one-quarter of the mean operating wave length of the antenna arrangement. For best operation, the expression ap- `prcmimately equal to one-quarter includes the range from one-eighth to three-eighths. Each such post I5 is received by a central aperture I6 provided in each of the radiating elements. 'I'he opposite end of ea'ch'post Vis similarly received by a corresponding aperture provided in conduit I4. Near this last mentioned end-oi 'each post there is'provided a flange Il having a rectangular configuration through which the post may be suitably secured by means of solder'- ing, brazing or welding to the conduit. In like fmanner, each of the radiating elements may be held securely to its individual supporting post.

The elemental radiators are excitedfrom Va coaxial antenna. feeder positioned within conduit I4 and having an cuter conductor V2) andan inner conductor 2l. Suitable spacers 22, 22v of insulating material, positioned'at spaced intervals along the inner conductor, maintain the desired relationship of elements 2.0 and 2l in conventional manner. The coaxial conductor arrangement is retained in position Within conduit Ill by means of A balance-to-unbalance connector unit is constructed at'one end of feederI 20, `2| to facilitate exciting the elemental 3 radiators. To this end, the outer conductor is longitudinally slotted, as indicated at 24, 24 for a distance approximately equal to one-quarter oi. the mean operating wave length. Therefore, the final section of the antenna feeder includes a first portion 20a and a second portion 20h as illustrated in Fig. 3. A conductive stud 25, centrally apertured to receive a reduced end portion of inner conductor 2|, is soldered or otherwise conductively connected with outer conductor section 20h. This portion 20h of the outer conductor may then be construed as a continuation of the inner conductor, while its opposite portion 20a functions electrically as a continuation of the normal outer conductor itself. A pair of

connectors

28, 28 is connected with section 20a to couple the outer conductor 20 of the coaxial feeder with radiating elements II and I3. These

connectors

28, 28 appear in Fig. 3 but are only partially shown in Fig. l. A similar pair of

connectors

29, 29 connected with section 20h extends the inner conductor 2l of the feeder to radiating elements I0 and I2, thereby to complete the circuit connections between the antenna and its feeder.

Connectors

29, 29 are also partially shown in Fig. 1 but appear in Fig. 3. Each of the elemental radiators is apertured near one end, as indicated at 30 in Fig. 2, to receive its exciting conductor.

The distance d of aperture from the excited end of the radiating element is selected to afford a desired impedance relation between the antenna and its feeder. The conduit I4 is apertured at 3l and 32 to permit the

connectors

23, 28 and 29, 29 to project therethrough for connection with the radiating elements. Each of the component parts of the described assembly, unless otherwise stated, may be formed of a highly conductive material, such as brass.

The described antenna assembly is enclosed within a suitable housing 35, selected of such material as to have no adverse effect on the radiation properties of the antenna. The housing is circular in cross section and may be constructed of plywood or a suitable plastic material. It provides a desired protection for the antenna structure from atmospheric conditions. One end plate 36 of the housing has a central aperture 3l through which the antenna feeder 29, 2| projects for connection to an associated signal-translating apparatus (not shown).

Spacer plates

38 and 39 maintain conduit I4 and the antenna elements supported thereby in a desired position within the housing. In most installations the antenna assembly is mounted with elements Ill-I3, inclusive, in a vertical plane. To facilitate arranging the figures on the drawings, the assembly is indicated in a horizontal position.

The described antenna is especially suited for operation over a wide range of wave lengths. The wide-band operation or broad response characteristic of the antenna is assured by the following features: (1) the diamond-shaped conductor utilized as the elemental radiator has a maximum width at its center where, in view of the described length of the element, a current maximum appears so that the conductive element has a minimum series inductance; and (2) the elemental radiator is narrow at its end portions where voltage maxima occur and, therefore, it has a minimum shunt capacitance. Additionally, the element has a large radiation resistance since its physical length closely approximates one-half the mean operating wave length of the arrangement. This is possible since it is not necessary to reduce the radiator length to effect end corrections otherwise necessary where the series inductance and shunt capacitance are large. A further feature is that the quarter-wave supporting posts I5 represent high impedances or function as high-frequency chokes which improve the efficiency of the elemental radiators. The antenna arrangement is predominantly directive in the plane at right angles to the axes of the radiating elements.

In the foregoing description and in the claims, the expression elongated conductive sheet of diamond shape is used to dene a conductive sheet which has its greatest width near the center, being narrow at the ends and having a thickness much less than its greatest width. Obviously, an antenna of this description is more easily constructed than the biconical antennas of the prior art mentioned above. In general, an arrangement of the type here disclosed may be substituted for any such prior art biconical radiator by providing an elongated conductor of diamond shape constructed to have approximately the same length as the biconicalradiatorandhaving a maximum width which is equal to twice thc greatest diameter of thebiconical element. Where this substitution criterion is followed, the elongated conductor of diamond shape exhibits the same radiation properties and impedance as the biconical element.

A single diamond-shaped radiator, constructed in accordance with the invention, is utilized as the antenna of Figs. 4 and 5. The element is designated 40 and is enclosed within a protective housing 4I which may be of a plastic or plywood material. This arrangement is suitable for support upon the fuselage of an airplane and, where it is intended for such use, the housing may have a teardrop or streamlined horizontal cross section. The wall thickness of the housing may vary as illustrated, being greatest at its leading edge. A

flanged ring 42 engages a horizontal portion 43 of the housing and may secure the assembly to the fuselage of an airplane through the agency of machine screws 44. A ground plane, in the form of al conductive metallic sheet 45, is provided in the assembly and connects with the outer conductor 46 of a coaxial-type antenna feeder through a suitable conductive connecting element 41. The radiating element 4D is connected with the inner conductive element 5I of the antenna feeder through a conductive plug 48 which is received by a bushing 49 secured to one end of the radiator. Connecting elements 4l and 48 are maintained in coaxial relationship through an insulating element 50 which supports the lower end of bushing 49 and the radiating element. Also, elements 4l and 48 are suitably tapered to assure proper impedance match between radiating element 40 and its feeder 46, 5I. |Ihe upper portion of the radiator has a. projection 52 which is received by a suitable cap element 53 encased within the dome of housing 4I. Resilient supports 54 are secured on the opposite faces of the radiator and are proportioned to engage the inner walls of the housing to maintain the radiator in a desired mounting position. The antenna of this invention is especially valuable for installations of the type represented in Figs. 4 and 5. The radiating element is very thin and, therefore, may be encased within a housing which may also be thin. This permits the streamlined housing to have suitable aerodynamic characteristics for use even on high-speed airplanes.

A V-type directive antenna, in accordance with the invention, is represented in Fig. 6. It consists of two coplanar conductive structures positioned in an angular relationship, indicated by the angle a. Each conductive structure includes a chain of series-connected elongated conductors or diamond shape. The conductors of one section are designated 6|, 62 and 63, While those of the alternate section are indicated 64, 65 and 66. Each elongated conductor may have a construction similar to that illustrated in Fig. 2 and those of a given chain are arranged end-to-end and are in abutting or continuously conductive engagement. The antenna structure may be excited by way of a feeder cable 69 connected with an input terminal 61 at one end of chain 6l, 62 and 63 and with an input terminal 68 at the adjacent end of chain 64, 65 and 66. The angle a is preferably so chosen that there is maximum radiation in the direction A, bisecting the angle.

In Fig 7 there is represented a loop antenna for operation over a wide range of wave lengths. As illustrated, it comprises four coplanar conductors of diamond shape 10, 7l, 12 and 73, individually having a construction similar to that illustrated in Fig. 2 and arranged to form a loop structure. A conductor 'l5 connects radiating elements 'H and 73 in parallel, while a conductor 76 connects the remaining elements 16 and i2 in parallel. An antenna feeder T9 excites the radiating elements. It is connected with input terminals 11 and 18 associated, respectively, with ating elements, which is characteristic of loop antennas.

While there have been described what are at present considered to be the preferred embodiments of this invention, it will be obvious to those skilled in the art that various changes and modications may be made therein without departing from the invention, and it is, therefore, aimed in the appended claims to cover all such changes and modications as fall within the true spirit and scope of the invention.

What is claimed is:

1. An antenna for operation over a wide range of Wave lengths comprising, an elongated conductive sheet of diamond shape having a length approximately equal to one-half the mean wave length of said range and a maximum thickness much less than its greatest width.

2. An antenna for operation over a wide range of wave lengths comprising, an elongated conductive sheet of diamond shape having a length approximately equal to one-half the mean wave length of said range and a uniform thickness much less than its greatest width.

3. An antenna for operation over a wide range of Wave lengths comprising, an elongated conductive sheet of diamond shape having a length approximately equal to one-half the mean wave length of said range, a maximum width of between one-quarter and one-half its length, and a maximum thickness much less than its greatest Width.

4. An antenna for operation over a wide range of wave lengths comprising, an elongated conductive sheet of diamond shape having a length approximately equal to one-half the mean wave length of said range, a maximum width approximately equal to one-third of its length, and a maximum thickness much less than its greatest width.

This structure has an omnidirective radiation pattern in the plane of its radi- 5. An antenna for operation over a wide range of wave lengths comprising, an elongated conductive sheet of diamond shape having a length approximately equal to one-half the mean wave length of said range and a maximum thickness much less than its greatest width, and a conductive post extending from the central portion of said conductor for securing said conductor to a supporting structure and having a length approximately equal to one-quarter of said mean wave length.

6. A loop antenna for operation over a Wide range of wave lengths comprising, four elongated conductive sheets of diamond shape arranged to form a loop structure and individually having a length approximately equal to one-half the mean wave length of said range and a maximum thickness much less than its greatest width.

7. A loop antenna for operation over a wide range of Wave lengths comprising, four elongated conductive sheets of diamond shape arranged to form a loop structure and individually having a length approximately equal to onehalf the mean wave length of said range and a maximum thickness much less than its greatest width, and means for exciting said conductors in pairs effectively to establish circulating currents in said loop structure.

8. An antenna for operation over a wide range of wave lengths comprising, a pair of coplanar conductive sheets of diamond shape arranged in aligned end-to-end relationship and individually having a length approximately equal to one-half the mean wave length of said range and a maximum thickness much less than its greatest Width.

9. An antenna for operation over a Wide range of wave lengths comprising, a chain of seriesconnected elongated and coplanar conductive sheets of diamond shape individually having a length approximately equal to one-half the mean wave length of said range and a maximum thickness less than its greatest width.

10. An antenna for operation over a wide range of wave lengths comprising, two coplanar conductive structures positioned in an angular relationship and individually including a chain of series-connected elongated conductive sheets of diamond shape each having a length approximately equal to one-half the mean wave length of said range and a maximum thickness much less than its greatest width.

HAROLD A. WHEELER.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,744,548 Hershey Jan. 21, 1930 1,807,386 Clarke May 26, 1931 2,059,186 Brown Oct. 27, 1936 2,064,112 Hermanspann Dec. 15, 1936 2,099,296 Carter Nov. 16, 1937 2,194,554 Katzin Mar. 26, 1940 2,283,938 McKesson May 26, 1942 2,359,620 Carter O'ct. 3, 1944 2,383,490 Kandoian Aug. 28, 1945 2,430,353 Masters Nov. 4, 1947 2,430,664 Bradley Nov. 11, 1947 2,433,183 Wolf Dec. 23, 1947 FOREIGN PATENTS Number Country Date 877,658 France Dec. 14, 1942