A High Gain, Wide Bandwidth and Low Cross-Polarization Compact Horn Antenna Fed by a Cavity-Backed Stacked Microstrip Antenna

A conical horn antenna fed by a cavity-backed two-layered suspended microstrip antenna has been proposed. The overall compact antenna with a length of 2.3λ0 yields a wide impedance bandwidth of 57% centred around 2.8 GHz with a very high gain of 19.9 dBi, an average gain of 17.5 dBi, and a radiation efficiency of above 88%. In effect, the gain of the basic two-layered suspended microstrip antenna is enhanced by 8.4 dB when it is backed by the cavity and the conical horn. A good radiation characteristic is obtained throughout the impedance bandwidth with main beam stability, high isolation between two such antennas, and low cross-polarization. Over the entire operating bandwidth cross-polarization lower than −30 dB with co-cross polarization isolation better than 50 dB is obtained in 45◦ plane. In comparison to conventional conical horn antennas yielding the same gain, the proposed antenna is more efficient with only 45% length. The prime contribution of the work is the concurrent yield of high 19.9 dBi gain, wide bandwidth, high efficiency, and good radiation characteristics including unidirectional stable radiation patterns, low cross pol., and high isolation between antennas which has not been reported so far. The proposed antenna is designed for various S-band FMCW Radars. © 2023, Electromagnetics Academy. All rights reserved.