A Novel Microstrip Antenna With Composite Patch Structure for Reduction of In-Band RCS

A novel kind of composite patch antenna is proposed, in which the mushroom-like electromagnetic band-gap (EBG) structure is integrated onto the conventional patch. Due to the high impedance property of the EBG structure, the scattering fields from EBG structure and the rest of antenna can be out of phase and cancel each other. The composite patch antenna exhibits a natural low in-band radar cross section (RCS) property and keeps the compact planar size as the conventional patch antenna. When radiating, the composite patch as a whole acts as the radiating part of the antenna; while scattering, the composite patch antenna can significantly reduce the in-band RCS within the main scattering beam direction, and the maximum reduction can reach 8 dBsm when plane wave is impinging from normal direction.