Ku/Ka-Band Dual-Frequency Shared-Aperture Antenna Array With High Isolation Using Frequency Selective Surface

In this letter, a high-gain, high-efficiency, and high-isolation Ku/Ka-band dual-frequency shared-aperture antenna array using a frequency selective surface (FSS) is investigated. The antenna consists of an 8 × 8 Ka-band and a 4 × 4 Ku-band printed double-sided dipole arrays in the upper and lower substrate layers, respectively. To realize high efficiency, the feeding networks are realized with double-sided parallel striplines. A low-pass FSS structure, sandwiched by the Ku-band array and the Ka-band array, works as the ground plane of the Ka-band array and is transparent to the Ku-band array, and it can also isolate the two antenna arrays for high isolations. In addition, a third-order impedance transform filter is integrated into the feed network of the Ka-band array. Ultimately, the antenna array has −10 dB impedance bandwidths of 14.47–17.52 GHz (19.07%) and 30.19–38.29 GHz (23.66%), with a peak antenna gain of 18.9 dBi at 16 GHz and 24.85 dBi at 35 GHz, respectively. High aperture efficiencies of 79% and 65% are realized. Meanwhile, the isolations between the two ports are better than 20 dB in the low band and 30 dB in the high band. For verification, a prototype is fabricated, and the measured results agree with the simulated ones.