Novel Ka-band microstrip antenna fed circular polarized horn array antenna

This paper introduces a novel microstrip antenna fed circular polarized array antenna composed of 8-element horn antennas. This horn can be divided into two parts, microstrip antenna and square horn. The microstrip antenna has the role of feeder and polarizer of the horn antenna, and it is designed for stacked type having a metal spacer for high gain, high isolation and wideband characteristic. And, the horn improves gain of microstrip antenna by about 2dB. By this structural characteristic, the horn antenna needs no additional structure such as feeder and polarizer, and the size can be considerably reduced. The element horn antenna has typical gain of 8 dBi and 3 dB axial-ratio bandwidth around 4.9 %. The horn array antenna was designed to have array spacing of 0.9 λ₀ with parallel feeding network. We obtained about 14 dBi array gain and 8.2 % axial-ratio bandwidth.