Mitigation of the Antenna Carrier Impact in Dual-Polarized Phased Arrays with Electromagnetic Bandgaps for Airborne SAR Sensors

In this work, the impact of the antenna carrier, an aerodynamic attachment structure that allows the antenna installment on the aircraft, is analyzed. The resulting polarization-dependent edge diffraction effects of a flight-model L-band phased array antenna, embedded in the antenna carrier, is experimentally validated. Measurements show a pattern distortion in the vertical polarization along with a gain reduction of 1 dB in the elevation plane, in which the beam steering is performed, that also corresponds to the E-plane, thus becoming this polarization more sensitive to edge diffraction effects. Further analysis is performed increasing the electrical size of the antenna carrier diameter up to 11 λ0. A low-profile and planar solution, based on Electromagnetic Bandgaps, is presented, by which the induced surface currents on the antenna carrier for the vertical polarization are mitigated, thus reducing the impact of edge diffraction effects without interfering in the performance of the horizontal polarization. Thereby, the desired radiation characteristics for both polarizations can be fulfilled regardless of the antenna carrier structure.