Common-Mode Resonance Suppressing Surface for Tightly Coupled Array

Common-mode resonance in traditional tightly coupled arrays (TCAs) limits bandwidth severely. In this communication, a common-mode resonance suppressing surface (CRSS) is proposed to mitigate the common-mode resonance. The CRSS is a surface etched with slots along the polarized direction placed below the antenna array to replace the ground of traditional TCAs. The CRSS cuts off the surface current on the ground, and thus the common-mode resonance is mitigated. Furthermore, a dual-linear polarized TCA embedded with the CRSS is simulated and manufactured, and the results show that it achieves an impedance bandwidth of 9.3:1 (0.6-5.58 GHz) and more than 90% radiation efficiency for broadside with the active VSWR <= 3.0. Besides, such an array remains the same bandwidth while scanning up to 60 degrees in the E- and D-planes and scanning up to 45 degrees in the H-plane with the active VSWR <= 3.5. Therefore, the CRSS shows a very promising application in engineering.