High-Isolation Wide-Angle Scanning L-/S-Band Shared-Aperture Phased Array Antenna Based on Self-Decoupling Technique

Cross-band interferences could deteriorate the performances of a dual-band shared-aperture phased array antenna (SAPAA), especially in small frequency ratio SAPAAs. This letter proposes novel self-decoupling techniques in an L-/S-band SAPAA to achieve out-of-band suppressions as low as -27.4 and -20.3 dBi for the radiations of L- and S-bands, respectively, and the cross-band port isolations are both more than 30 dB, with peak values exceeding 60 dB, without the need for additional filter circuits or decoupling structures. In addition, new technique of capacitive coupling folded arm is proposed to realize wide-beam and wideband characteristics. The shared-aperture structure is formed by a staggered arrangement of 4 × 4 L-/S-band end-fire dipole antennas. As a result, the scanning range of the SAPAA can achieve ±60°/±70° in the E-/H-plane at 1.5–1.8 GHz with VSWRs under 3.3, and it can achieve ±60° in both the E-/H-plane at 2.5–2.9 GHz with VSWRs under 3.3. The consistency of the measurement and simulation validates the designs