A new microstrip array antenna with cosecant-squared beam shaping as a radiating column for SSR

Radiating Column of SSR antennas play an important role in final pattern formation. In this paper, a microstrip array antenna with modified cosecant squared pattern is designed to work as radiating column of SSR´s antennas in L band. This simple structure consists of a feed network with 11 elements of half-wave printed dipoles as radiating elements. Synthesis pattern method used to obtain required amplitude and phase of elements for desired pattern. Wilkinson power dividers are used to prepare desired power amplitudes to feed elements. A special corporate feed network with constant group delay used to provide wide frequency bandwidth. Main beam of designed antenna has about 9 degrees tilt above the ground in the elevation plane, nearly 10 dB gain and 50 degree elevation beam width in -10 dBc. Return loss in center frequency (1060 MHz) is 22 dB. Rogers´s RT Duroid 5880 with thickness of 31 mil is used as laminate in design. The proposed one-layer microstrip array with low complexity and low manufacturing and maintenance cost can be used in all SSR antennas.