An Antenna Array with Cosecant Radiation Pattern for One-Dimensional Scanning

The results of design of an X-band linear antenna array with cosecant radiation pattern in elevation plane are given. The antenna array and its feeder are implemented by printed technology. The radiator of the array is a microstrip patch. Calculated characteristics of the radiator in the operating band are given. To implement the cosecant radiation pattern it is necessary to find such amplitude and phase distributions over the radiators, that the difference between obtained radiation pattern and the desired one (cosec2θ) is minimal. A number of options were considered for the amplitude distribution, from which a «cosine on a pedestal» distribution was chosen. The phase distribution was obtained by using the Kondratiev-Hzmalyan phase synthesis method. The feeder of the array is a parallel-type balanced stripline splitter. To eliminate the drawbacks of the balanced stripline, the screening by metalized vias was used. An example of the effective use of such screening is given. To implement the desired amplitude and phase distributions, non-symmetric T-junctions and meander delay lines were used. Calculation of the array radiation pattern was done and the results were compared with an ideal cosecant beam.