A grid array antenna with C-figured elements

The radiation characteristics of grid antennas are investigated. A balanced feed grid array antenna (a balanced feed GA), which radiates a linearly polarized wave and is used as a reference antenna, has a half-power beamwidth (HPBW) of 19 degrees in the phi = 0 degrees plane and 18 degrees in the phi = 90 degrees plane. The gain of the balanced feed GA is calculated to be 19.1 dBi. It is shown that a circularly polarized wave is obtained when C-figured elements are added to the balanced feed GA. The rotation angle of the C-figured elements for a right-hand circularly polarized wave is phi (rot) = 135 degrees, while that for a left-hand circularly polarized wave is phi (rot) = 45 degrees. The HPBW and gain of the balanced feed CGA are almost the same as those of the balanced feed GA. In addition to the balanced feed GA and CGA, unbalanced feed GA and CGA are also analyzed. It is found that the HPBW of the unbalanced feed GA is almost the same as that of the balanced feed GA. Similarly, the HPBWs of the unbalanced feed CGA and the balanced feed CGA are almost the same. The axial ratio and gain of the unbalanced feed CGA at the center frequency are 0.2 dB and 17.3 dBi, respectively. The frequency bandwidths for the axial ratio and gain of the unbalanced feed CGA are calculated to be both approximately 8%. (C) 2001 Scripta Technica.