A Compact Dual-CP Planar Monopulse Array With High Efficiency and Enhanced Sidelobe Suppression

A compact planar circularly polarized (CP) monopulse array antenna at the S-band based on an air-filled substrate integrated coaxial line (AF-SICL) feeding structure to suppress sidelobes in both sum and difference beam is proposed in this article. The AF-SICL and the stacked patch are tightly integrated to achieve subarray sequential rotation structure with unequally spaced elements, combined with an unequal amplitude feed network with a large power division ratio contributing to reducing trans