Radio frequency antenna and method of manufacture thereof

Abstract

A novel RF antenna and method of manufacture thereof is disclosed. With this novel antenna the energy radiates in all directions including both left hand and right hand polarizations. In one embodiment of the invention, the antenna consists of two equal size rectangularly shaped conductive sheets positioned in parallel with each other. The side dimensions are nearly a half wavelength of the center frequency. The rectangle is nearly a square with one dimension slightly larger than the other. The feed point is at any of the corners. The difference in side dimensions cause the antenna to resonate at two adjacent frequencies, one slightly above the working frequency and the other slightly below. This creates a phase difference between the orthogonal modes of operation at the working frequency. A 90 degree phase difference generates circular polarization. Other embodiments include using circularly shaped conductive plates, placing cutouts in one dimensions of the rectangularly shaped conductive sheets, placing transverse cut outs in the center of the conductive sheets, placing discrete components between the conductive plates and using a phase shift network to generate two feed pints rather than one. Another embodiment discloses an antenna exhibiting polarization diversity. The antenna of this embodiment is constructed with two feed point on adjacent corners.