Characteristic Mode Cancellation Method and Its Application for Antenna RCS Reduction

Abstract

This letter proposed a characteristic mode cancellation method for design of an antenna radar cross section (RCS) reduction. Two kinds of subarrays whose unit cells are composed of a square patch with a circle hole and a cross patch, respectively, are designed. With the characteristic mode theory, the currents represented by the characteristic modes of two subarrays flow in an opposite direction. By arranging two subarrays into a checkerboard patterned array, cancellation of their characteristic modes is achieved and, thus, the resultant RCS of the whole array is greatly reduced. The checkerboard array is integrated with a microstrip antenna to reduce its RCS. The simulated and measured results are in good agreement and show that with the checkerboard array, the operating band of the reference microstrip antenna covering 8.32-9.32 GHz keeps unchanged, and the -10 dB broadband RCS reduction both in band and out of band of the microstrip antenna is from 6.4 to 21.4 GHz with an in-band gain increase of 1 dB.