Development of a $Ka$ -Band Wideband Circularly Polarized 64-Element Microstrip Antenna Array With Double Application of the Sequential Rotation Feeding Technique

A novel -band wideband circularly polarized 64-element microstrip antenna array is presented in this letter. It is developed with double application of the sequential rotation feeding technique. The array employs corner-truncated microstrip patches as the basic element, and then a four-element array as the subarray. By applying the sequential rotation technique twice to design the feed networks, a full 64-element array with good performance is obtained. A prototype of the full array was constructed and tested. The measurement results show that both the reflection coefficient of less than 10 dB and axial ratio of less than 3 dB have been achieved over a frequency band of 27-31 GHz; this corresponds to a wide bandwidth of 13.8%. Due to its planar configuration, the proposed array can find good applications in aerospace, radar, and communication systems.