Compact UWB and Low-RCS Vivaldi Antenna Using Ultrathin Microwave-Absorbing Materials

In this letter, we present an improved Vivaldi antenna by using ultrathin microwave-absorbing materials (MAMs). The reverse currents at the outer side edges of the Vivaldi antenna always distort its radiation patterns and worsen its VSWR in some frequencies. To solve this problem, the ultrathinMAMs are loaded at the side edges of the antenna to absorb the energy of the current, and also to reduce its radar cross section (RCS). Simulated and measured results show that the proposed antenna operates from 0.8 to 15.5 GHz with VSWR < 2.15, and its gains are more stable than those of the antenna withoutMAMs in a very wide frequency band. The average monostatic RCSs of the proposed antenna in 218- GHz band and theta is an element of [-30 degrees, + 30 degrees], phi = [-45, + 45 degrees] angle range are less than 0.001 m2, which make it very attractive for a variety of applications.