US3656168A

US3656168A - Spiral antenna with overlapping turns

Info

Publication number: US3656168A
Application number: US146819A
Authority: US
Inventors: George T Stropki
Original assignee: North American Rockwell Corp
Current assignee: Boeing North American Inc
Priority date: 1971-05-25
Filing date: 1971-05-25
Publication date: 1972-04-11
Anticipated expiration: 1989-04-11

Abstract

An antenna of the type that radiates a circularly polarized electromagnetic energy field is constructed with one of an included pair of transversely overlapping double-wound spiral conductors secured to a different one of substantially parallel opposite surfaces of a dielectric support means. The improved broad band antenna radiates energy in the range of approximately 2 to 17 GHZ without radiation pattern degradation at higher peak power values in comparison to conventional circularly polarizing antennas.

Description

United States Patent Stropki [451 Apr. 11, 1972 [54] SPIRAL ANTENNA WITH [56] References Cited OVERLAPPING TURNS UNITED STATES PATENTS [72] Gamma Ohm 3,509,465 4/1970 Andre et a]. ..343/895 [73] Assignee: North American Rockwell Corporation, El

Segundo, Cahf- Primary Examiner-Eli Lieberman [22] Filed; May 25, 1971 Attorney-L. Lee Humphries and Daniel H. Dunbar pp 146,819 57 ABSTRACT Related U.S. Application Data An antenna of the type that radiates a circnlarly polarized [63] continuatiomimpan Ofser. No 856,283 Sept. 1969 electromagnetic energy field is constructed with one of an meluded pair of transversely overlapping double-wound spiral abandoned.

. conductors secured to a different one of substantially parallel 52 us. Cl ..343/895 PP Surfaces ofa dielectric support means- The impmved 5 CL 01 1 3 broad band antenna radiates energy in the range of approxi- 58 Field of Search ..343/s95, 908 mately 2 to 17 6111 without radiation Pattern degradation at higher peak power values in comparison to conventional circularly polarizing antennas.

2 Claims, 6 Drawing Figures PATENTEDAPR I 1 I912 SHEET 1 BF 2 IN VENTOR.

GEORGE T. STRQPKI ATTORNEY PATENTED APR 1 1 I912 SHEET 2 BF 2 INVENTOR.

GEORGE T. STROPKI ATTORNEY SPIRAL ANTENNA WITH OVERLAPPING TURNS CROSS-REFERENCES This is a continuation-in-part application of application for U.S. Pat. Ser. No. 856,283, filed Sept. 9, 1969 but now abandoned in favor of this application.

SUMMARY OF THE INVENTICN The antenna of this invention is constructed with a dielectric support member having essentially parallel opposite surfaces, such member normally being formed from a polymerized organic resin having reinforcing glass fibers or from a comparable dielectric composition. A pair of spiral metallic conductors is preferably configured on and adhered to the dielectric support member by conventional etched or printed circuit manufacturing processing or the like, each conductor being supported entirely on a different one of the parallel opposite support member surfaces. The individual conductors are each normally electrically energized from a center feed terminal by a conventional balun or coaxial feed assembly; such conductors are also normally either openended or sometimes terminated at a perimeter terminal to a conventional matching circuit. The individual conductors also are closely spaced in their transverse projected relationship relative to each other to provide a reduced axial ratio antenna operating characteristic, are energized by high frequency (2 to 17 GH,) alternating electrical currents that amplitude-wise are continuously 180 out of phase with respect to each other SUMMARY OF THE DRAWINGS FIG. 1 is a sectional view of a flat double-wound spiral antenna having the biplanar conductorfeatures ofthis invention;

FIGS. 2 and 3 are plan views of the antenna of FIG. I showing the conductor configurations at the opposite surfaces of the antenna dielectric support means;

FIG. 4 is a sectional view of a flat double-wound spiral antenna having the features of this invention but with individual conductors of varying width; and

FIGS. 5 and 6 are plan views of the antenna of FIG. 4 showing the conductor configurations at the opposite surfaces of the antenna dielectric support means.

DETAILED DESCRIPTION FIG. 1 illustrates a section through a circularly polarizing antenna 10 having flat dielectric support member 11 provided at its opposite planar surfaces 12 and 13 with

metallic conductor elements

14 and 15, respectively. In many applications, dielectric support means 11 may be a polymerized organic resin such as polytetrafluoroethylene reinforced with glass fibers or a similar composite with other organic resin material such as a polyphenylene oxide or an epoxy.

Conductors

14 and 15 are configured and adhered to the opposite surfaces 12 and 13 of dielectric support means 11 in a conventional manner as by state-of-the-art antenna design and etched or printed circuit board manufacturing techniques. As shown in FIGS. 2 and 3,

conductors

14 and 15 specifically may each have an equiangular spiral configuration wherein the conductor is also substantially of uniform width from near its centered feed terminal 16 (or 17) to near its respective perimeter terminal 18 (or 19). In other applications such conductors may be Archimedian spirals, for example, or may have square spiral configurations rather than essentially circular spiral configurations. The invention also has application to configurations for dielectric support member 11 other than the essentially flat, plate-like or sheet-like dielectric support member shape of the drawings. For instance, the invention has application to hollow, conically or pyramidally shaped dielectric base means since it is only critical that each one of the paired conductors be provided substantially on a different one of opposed, essentially parallel support surfaces and in transversely overlapping relationship relative to each other. Such invention in instances permits an increase in peak power handling capability from approximately 500 watts to as much as nearly 5,000 watts for the bisurface transversely overlapping conductor arrangement over the single surface conventional circular polarizing antenna construction with equivalent double-wound conductor widths, spacings, and lengths. The improvement is effected without significant radiation pattern degradation and without antenna radiation voltage breakdown.

The antenna embodiment 20 of FIGS. 4 through 6 illustrates the required conductor transverse overlap relationship that is effective to obtain a significant increase in peak power handling capability in connection with the instant invention. Such is accomplished by transversely overlapping the widths of the

individual conductors

24 and 25 secured to support

surfaces

22 and 23 of dielectric member 21 in the regions from

feed terminals

26, 27 to

perimeter terminals

28, 29 in the general manner shown in FIGS. 5 and 6. As shown therein,

conductors

24 and 25 each have a maximum width in a region of the conductor length nominally associated with the center frequency of the desired antenna operating band-width and the maximum width of conductor 24 considerably overlaps the edges of the transverse projected widths of the adjacent turns of conductor 25 and vice versa. In fact, except for a relatively narrow separation between adjacent edges of a conductor in a radial direction, each conductor may approach being sheet-like in its basic configuration.

This relationship is readily facilitated by the fact that the individual conductors are secured to the

opposite support surfaces

22 and 23 of dielectric base means 21 and results in a significantly reduced impedance value for the antenna assembly, other construction characteristics being equal. In one specified embodiment of a circularly polarizing antenna with a square spiral configuration, the assembly impedance was reduced from ohms to approximately 50 to 60 ohms by use of the varying width conductors on opposite surfaces of the dielectric base. In terms of increased peak power, for a given input power level the peak power can be further increased approximately 40 percent by the transversely overlapping conductor feature in the bisurface antenna arrangement.

The instant invention is not limited in its application to antenna constructions utilizing either uniform width or variable width conductors. More specifically, the transversely overlapping conductor relationship necessary to obtain a significant reduction in antenna impedance may also be developed with other conductor forms such as the slow wave antenna conductors shown in U.S. Pat. Nos. 3,454,95l and 3,465,346.

By incorporating the features of this invention in a circularly polarizing antenna it is possible to obtain antenna impedances to as low as approximately 50 ohms. The use of such transversely overlapping conductor features in an antenna also permits the use of simple coaxial fieed devices rather than balun devices, thereby contributing further to the improved power handling capacity of the invention. It should be noted that the opposed conductors are fed. with radio frequency signals that are out of phase with respect to each other. At the radiation band the fields radiated from the transversely overlapping conductor sections are coupled and reinforce each other.

I claim: I

1. In an antenna of the type which radiates a circularly polarized electromagnetic energy field, in combination:

ments being adhered substantially entirely to a different one of said dielectric support means exterior opposed essentially parallel support surface areas, and also being positioned in substantial transversely overlapping relationship relative to each other in the principal radiating regions of the element.

2. The invention defined in claim 1, wherein said multipletum spiral conductor elements are each varied in width in their length from a region near the connected one of said feed terminals to a region near an associated perimeter terminal.

Claims

1. In an antenna of the type which radiates a circularly polarized electromagnetic energy field, in combination: a. Dielectric support means having exterior opposed essentially parallel support surface areas, b. A pair of feed terminals that each conduct a different one of two equal-amplitude electrical currents continuously 180* out of phase with respect to each other, and c. A pair of multiple-turn spiral conductor elements that are each electrically connected to a different one of said feed terminals and that together radiate a circularly polarized electromagnetic energy field, each one of said pair of multiple-turn spiral conductor elements being adhered substantially entirely to a different one of said dielectric support means exterior opposed essentially parallel support surface areas, and also being positioned in substantial transversely overlapping relationship relative to each other in the principal radiating regions of the element.

2. The invention defined in claim 1, wherein said multiple-turn spiral conductor elements are each varied in width in their length from a region near the connected one of said feed terminals to a region near an associated perimeter terminal.