US2648001A

US2648001A - Ring type antenna

Info

Publication number: US2648001A
Application number: US661205A
Authority: US
Inventors: Howard J Rowland
Original assignee: US Department of Navy
Current assignee: US Department of Navy
Priority date: 1946-04-11
Filing date: 1946-04-11
Publication date: 1953-08-04
Anticipated expiration: 1970-08-04

Description

Aug. 4, 1953 H. J. ROWL AND RING TYPE ANTENNA Filed April 11 1946 INVENTOR., HOWARD J. ROWLAND ATTORNEY Patented Aug. 4, 1953 Howard J. Rowland, Brookline, by mesne assignments, ta the;

Mass assignor; United States. of

America as represented by the- Secretary of the Navy Application April 11, 1946, Serial No. 6615205 5 Claims.

This invention relates to an antenna, and

more particularly to acompact multi-element' ring antenna having integral impedance matching stubs.

Ring type multi-eiement antennas are often employed when an omnidirectional radiation pattern is desiredin the plane of polarization of the antenna. A conventional type employs a plurality of half-wave radiating elements arranged in arcs concentric with a coaxial feed line. When used at frequencies in which the length of the dipoleelements becomes appreciable, the physical dimensions become large and acomparatively bulky assembly results. Provision for effecting an impedance match of the radiating elements to the transmission line is not included in conventional ring elements. Such matching is usually accomplished by the application of" transformers. to the transmission line.

It is an. object of this invention. to provide an improved mul-ti-element ring antenna.

It isa further object of this invention to provide a. compact multi-element ring antenna.

It is still another object of this invention to provide a compact multi-element ring antenna having, integral means for-impedance matching. These and other objects will be more apparent upon consideration of the following description together with the accompanying drawings, Fig. 1 of which is a perspective view of an embodiment of the present invention. Fig. 2 is a partial plan view of the ring antenna of Fig. 1 showing the disposition of an adjustable probe member.

Referring to the drawings, a metallic central collar 5, of proper diameter to fit snugly over the outer conductor of an associated conventional transmission line, such as a coaxial line or circular wave guide (not shown), provides a rigid central support for three similar dipole radiators, each occupying a 120 degree segment of a circle as shown. Spaced parallel dipole supporting arms 6 and 1 extend radially from collar 5 and support at their outer ends arcuate dipole elements 8 and 9. Dipole element 8 extends at inner end 8' into the space between arms 6 and l and toward element 9. An aperture 4 is located in the extension 8', and is positioned midway between arms 6 and 1. An adjustable probe I0 is threaded through the aperture 4 and extends inwardly to a predetermined position within the transmission line enclosed by collar 5. It has been found desirable that the separation between the radiating dipole elements in the plane of the elements be approximately 180 2 electrical degrees for some applications, such as when a plurality of ring elements is employed'in an end flre linear array. Because of the rather large dimensions of collar 5, as compared with the. wavelength usually used, the electrical length of arms-6 and 1 will be somewhat less than 90- degrees, thereby presenting an inductive reactance at the operating frequency. 'Iheeffect of this reactance is neutralized by the addition of short parallel stubsl3 and I4, illustrated as integralextensions of the elements 8 and 9, which stubs present a capacitive reactance at the operating frequency. Thus, the impedance presented by the antenna to the transmission line is controlled by stubs f3 and I 4, eliminating the requirement of an additional impedance matching transformer in the transmission line; The plane of the placement of stubsl3 and M is unimportant. As shown in the drawings, they are placed in a plane perpendicular to that of the antenna to provide acompact assembly.

As is well known, the current distribution along a dipole is suchthat the free ends of the dipole contribute very little radiated energy compared with the central, or high current region; In order further to conserve space, the free ends of the dipole elements 8 and 9- have been folded to formloading stubs H- and IZ" respectively. Since some current will flow through stubs II and [2, it is desirable that they be placed in the same plane as the dipole elements 8 and 9 as illustrated to prevent cross-polarization effects.

The above described folded dipole unit comprises only one of three similar symmetrical assemblies, which as shown in the drawings are combined and secured to collar 5 to form a complete antenna. It is not intended that the number of similar units shall be restricted to three, since any number of dipole elements lying in a common circle may be employed if sufficient space is available. Since certain other changes may be made in the above described article and different embodiments of the invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense, and therefore that the invention is to be limited only by the prior art and the spirit of the appended claims.

What is claimed is:

1. An antenna structure comprising, a central collar, a plurality of pairs of supporting arms extending radially outward from said central collar,

a plurality of arcuate dipole radiating elements arranged in a common circle in a common plane, each of said dipole elements being secured at one end to a separate one of said supporting arms, the unsecured ends of said dipole elements extending radially inward toward said central collar, and a plurality of pairs of metallic stubs integrally joined to said dipole elements at the point of connection thereof with said supporting arms and extending perpendicularly in one direction from the plane of said dipole elements.

2. An integral antenna structure comprising, a central supporting collar, a plurality of paired supporting arms extending radially outward from said collar, a dipole element secured at one end to the extremity of each supporting arm with each pair of arms supporting a dipole, said dipole elements being of arcuate form and arranged in a common circle concentric with said collar, and a like plurality of paired metallic stubs integrally joined to said dipole elements at the point of connection thereof with said supporting arms, the stubs of each pair being parallel to each other and extending from said dipole.

3. An integral antenna structure comprising, a central supporting collar, a plurality of paired supporting arms extending radially outward from said collar, a dipole element secured at one end to the extremity of each supporting arm with each pair of arms supporting a dipole, said dipole elements being of arcuate form and arranged in a common circle, the unsecured ends of said dipole elements extending radially inward toward said collar, and a like plurality of paired metallic stubs integrally joined to said dipole elements at the point of connection thereof with said supporting arms and extending parallel to the axis of said collar in one direction from said dipoles.

4. An integral metallic antenna structure comprising, a central supporting collar adapted to be supported externally of a transmission line, a plurality of paired supporting arms extending radially outward from said collar, a dipole element connected at one end to the end of each supporting arm with each pair of arms supporting a dipole, said dipole elements each being 01 arcuate form and arranged in a common circle concentric with said collar in a plane perpendicu- 4 lar to the axis of said collar, the ends of said dipole elements not connected to said supporting arms being turned inwardly and extending a short distance radially toward said collar to provide capacitive coupling between adjacent dipoles, and a like plurality of paired metallic stubs integrally joined to said dipole elements at the point of connection thereof with said paired supporting arms and extending parallel to the axis of said collar in one direction from the plane of said dipole elements.

5. An integral metallic antenna structure comprising, a central supporting collar adapted to be supported externally of a transmission line, a plurality of paired supporting arms extending radially outward from said collar, a dipole element connected at one end to the end of each supporting arm with each pair of arms supporting a dipole, said dipole elements each being of arcuate form and arranged in a common circle concentric with said collar in a plane perpendicular to the axis of said collar, an exciting probe connected at on end to the end of one element of each dipole and extending inwardly through said collar, the ends of said dipole elements not connected to said supporting arms being turned inwardly and extending a short distance radially toward said collar to provide capacitive coupling between adjacent dipoles, and a like plurality of aired metallic stubs integrally joined to said dipole elements at the point of connection thereof with said paired supporting arms and extending parallel to the axis of said collar in one direction from the plane of said dipole elements.

HOWARD J. ROWLAND.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,283,897 Alford May 16, 1942 2,289,856 Alford July 14, 1942 2,324,462 Leeds July 13, 1943 2,402,635 Kandoian June 25, 1946 2,413,085 Tiley Dec. 24, 1946 2,416,246 Wheeler Feb. 18, 1947 2,512,137 Buchwalter June 20, 1950.,