Circularly-polarized antenna system using tilted dipoles

DETAILED DESCRIPTION What is claimed is: 1.
An omnidirectional circular polarization antenna system comprising: a plurality of dipoles equally spaced from one another about a conductive support mast with the dipoles equally spaced from the mast with their centers lying on a circle in a plane orthogonal to said mast, each of said dipoles having dipole halves with the one dipole half extending above and the other dipole half extending below said plane and the dipole halves being tilted at the same acute angle with respect to said plane, means for exciting said dipoles in rotating phase where the mode number equal to the number of 360.
degree.
phase changes about the ring of said dipoles is an integer other than zero, said tilt angle being determined to radiate from said antenna system circularly polarized waves omnidirectionally broadside said mast.
2.
The combination of claim 1 wherein said plurality of dipoles is four and the mode number is 1.
3.
The combination claimed in claim 1 wherein said dipoles are tilted with respect to said plane at an angle of about 36.
degree.
.
4.
The combination claimed in claim 1 wherein the number of dipoles is eight and the mode number is 2.
5.
The combination claimed in claim 4 wherein said dipoles are tilted with respect to said plane at an angle of about 36.
degree.
.




Description:
BACKGROUND OF THE INVENTION This invention relates to dipole antenna systems and more particularly to a circularly polarized dipole antenna system for FM and TV broadcast.
The term circularly polarized as used herein refers to the general class of elliptically polarized antennas with low axial ratio.
Circularly polarized omnidirectional antennas using slanted or tilted dipoles are known.
See, for example, an article in RCA Review dated June 1947, Vol.
VIII, No.
2 entitled, "Circularly-Polarized Omnidirectional Antenna" by George H.
Brown and Oakley M.
Woodward, Jr.
, pp.
259 thru 269.
Also, see Lindenblad U.
S.
Pat.
No.
2,217,911.
In these arrangements, four slanted dipoles are fed in-phase or in a mode zero (H=O) condition