US3727231A

US3727231A - Collinear dipole antenna

Info

Publication number: US3727231A
Application number: US00183388A
Authority: US
Inventors: J Galloway; L Griffee
Original assignee: Collins Radio Co
Current assignee: Collins Radio Co
Priority date: 1971-09-24
Filing date: 1971-09-24
Publication date: 1973-04-10
Anticipated expiration: 1990-04-10

Abstract

A collinear dipole array antenna including feed means whereby the dipoles are energized in phase independent of frequency over the operating frequency range.

Description

United States Patent 1 1 Gallowayetal.

[s41 COLLINEAR DIPOLE ANTENNA v [56] References Cited UNITED STATES PATENTS [75] Inventors: John W. Galloway, Richardson; Leslie V. Griffee, Dallas, both of 343/821 X ..343/821 X 343/821 X .343/821 X 5/1961 Chu et Melancon....................... 1 1/1950 Wehner......

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[21] APPl- 183,388 Primary Examiner-Rudolph V.Ro1inec Assistant Examiner-Saxfield Chatmon, Jr.

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4 Claim, 2 Drawing Figures 1 COLLINEAR DIPOLE ANTENNA This invention relates to electromagnetic radiating antennas, and more particularly to a dipole antenna utilizing collinear dipole arrays.

An object of this invention is an improved antenna utilizing collinear dipole arrays.

Another object of the invention is a collineardipole array antenna with novel feed means for energizing said arrays in phase independent of frequency over an operating frequency range.

Still another object of the invention is an improved collinear dipole array antenna providing a 360 horizontal radiation pattern.

Briefly, a dipole antenna in accordance with the present invention comprises a support mast and two dipole structures mounted collinearly thereon. Preferably, said dipoles comprise bicones whereby 360 radiation is provided, and said mast is hollow whereby coaxial feed means may be housed therein.

An important feature of the invention is novel feed means which is economical and which energizes said dipoles in phase independent of frequency whereby the radiation pattern lobe maximum is always directed toward the horizon. The coaxial feed means is provided internally in said mast to said dipoles and is connected to stripline transmission means mounted externally to said mast and between the input terminals of each of said dipoles. Said stripline transmission line means is discontinuous at the midpoint between the two dipoles thereby providing two stripline transmission line segand said dipoles are energized in .phase by proper dipole element connection. I p

The invention and objects and features thereof will be more readily apparent from the following detailed description and appended claims when taken with the drawing, in which: n 3

FIG. 1 is an isometricview of a collineardipole antenna in accordance with the present invention; and

FIG. 2 is a schematic view of the antenna of FIG. 1 in section and illustrates the novel feed system in accordance with the present invention.

Referring now to the drawing, FIG. 1 is an isometric view of a collinear dipole antenna in accordance with the present invention and in which the cylindrical housing portion is removed. A central hollow mast 10 is provided with

support members

12 and 14 at either end thereof which receive thecylindrical housing member (removed in this view for illustration). Mounted collinearly on mast 10 are two bicone dipole radiating elements shown generally at 16 and 18.

Conical elements

20 and 22 are insulatively mounted on mast l0 and comprise bicone l6; similarly,

conical elements

24 and 26 areinsulatively mounted on mast '10 and comprise bicone 18. Each of the bicones functionsas radiating dipoles in which the radiation pattern is omnidirectional toward the horizon.

In order to accomplish the pattern load maximum directed toward the horizon, each of the dipole arrays must be fed in phase. To accomplish this over a narrow bandwidth is quite simple, but when the bandwidth is large and the feed system must be external to the central mast feed systems may become quite complex.

As illustrated in the cross section of the antenna array illustrated in FIG. 2, a novel feed system in accordance with the present invention is simple in structure while operable over a wide frequency range. The two biconical arrays 16' and 18 are insulatively mounted on mast 10 by

insulators

30 and 32 which function as quarter-wave chokes at the center frequency of the spectrum to be radiated. Coaxial feedline 34 which is preferably situated within mast 10 is passed externally at point 36 and terminates at a point' 38 equidistant between bicone 16 and bicone 18. Extending from point 38 to the input of bicone .16 is a stripline 40 including base plane 42 and top conductor 44. The center conductor of coaxial line 34 is connected to the top conductor 44 which, in turn, is connected to the upper cone 20 of bicone 16. Ground plane 42 is con nected to the bottom cone 22.

Extending from point 38 downwardly to bicone 18 is a conductor 46 which cooperatively functions with the outer conductor of coaxial line 34 as a second-stripline. Conductor 46 is electrically connected to upper cone 24 of bicone 18, and the outer conductor of coaxial line 34 is electrically connected to the bottom cone 26 of bicone 18.

The simple structure of the described feed system provides for inphase energization of the two bipole arrays for any operating frequency. The transposition at terminal point 38 of coaxial line 34 induces a current in conductor 46 which is in phase with the current flowing in the center conductor of coaxial line 34. Further, the current flowing on the outer surface of the outer conductor of coaxial line 34 is in phase with the current induced in ground plane 42 of stripline 40.

Thus, conical element 20, which is energized by the center conductor of coaxial line 34, and upper conical element 24 of bi cone-l8,'which is energized by conductor 46, will always be in phase at any operating frequency. Similarly, conical element 22 of bicone 16, which is energized by ground plane 42 of stripline 40, and the bottom cone 26 of bicone 18, which is energized by the outer surface of outer conductor of coaxial line 34, are energized in phase at any operating frequency.

Collinear dipole antennas in accordance with the present invention have proved to be very economical in construction with satisfactory operation across a relatively wide frequency band. One such antenna designed for use in ground-to-air communication and operating from 225 to 400 megahertz has a VSWR of less than 2:1. The antenna gain varies from 4.0 to 5.0 db over isotropic and has an average power range of 5 kw. Because the array may employ a hollow continuous mast thereby minimizing weight, several such units may be stacked and supported by the space flanges on the end portions of the antennas. 7

While the invention has been described with reference to a specific embodiment, the description is illustrative and is not to be construed as limiting the scope of the invention. Various modifications and changes may occur to those skilled in the art without departing from the spirit and scope of the invention as defined by the appended claims.

We claim:

l. A vertically polarizable antenna having a horizontal radiation pattern comprising a support mast, two

dipoles insulatively mounted collinearly on said mast,

coaxial feed means, first and second stripline means, said first stripline means comprising a ground plane extending from a point between and equidistant from each of said dipoles to and electrically connected with a first element of a first of said dipoles, said second stripline means comprising a ground plane and a conductor extending from said point to the other of said dipoles with said ground plane and said conductor connected to respective elements of said other dipole, said coaxial feed means running parallel with and spaced from said first stripline means whereby the outer conductor of said feed meanscooperatively functions as part of said first stripline, said coaxial feed means terminating at said point, means interconnecting the center conductor of said feed means and said conductor of said second stripline means, means connecting said outer conductor with a second element of said first dipole, and means electrically connecting said ground plane of said first stripline means to said first element of said first dipole, whereby said two dipoles are energized in phase independent of frequency over a wide operating frequency range.

2. An antenna as defined by claim 1 wherein said dipoles comprise bicones whereby 360 radiation is provided.

3. An antenna as defined by claim 2 wherein said mast is hollow and said coaxial feed means is positioned within said mast and emerges outside said mast near said dipoles.

4. An antenna is defined by claim 1 wherein support flanges are provided at both ends of said mast whereby a plurality of antennas may be stacked.

Claims

1. A vertically polarizable antenna having a horizontal radiation pattern comprising a support mast, two dipoles insulatively mounted collinearly on said mast, coaxial feed means, first and second stripline means, said first stripline means comprising a ground plane extending from a point between and equidistant from each of said dipoles to and electrically connected with a first element of a first of said dipoles, said second stripline means comprising a ground plane and a conductor extending from said point to the other of said dipoles with said ground plane and said conductor connected to respective elements of said other dipole, said coaxial feed means running parallel with and spaced from said first stripline means whereby the outer conductor of said feed means cooperatively functions as part of said first stripline, said coaxial feed means terminating at said point, means interconnecting the center conductor of said feed means and said conductor of said second stripline means, means connecting said outer conductor with a second element of said first dipole, and means electrically connecting said ground plane of said first stripline means to said first element of said first dipole, whereby said two dipoles are energized in phase independent of frequency over a wide operating frequency range.

2. An antenna as defined by claim 1 wherein said dipoles comprise bicones whereby 360* radiation is provided.