Design of Broadband Low-RCS Array Antennas Based on Characteristic Mode Cancellation

In this letter, a design method for low radar cross section (RCS) array antennas based on characteristic mode cancellation (CMC) is presented. Based on the characteristic mode theory (CMT), two novel microstrip elements are designed by introducing rectangular slots and cross slots, which produce 180° scattering phase difference by adjusting the size of slots. The dominant characteristic modes of the two elements achieve broadband dual-linear polarization CMC and similar radiation performances. The 4 × 4 array antenna consisting of these two antenna elements is designed. The operating band is from 4.55 GHz to 5.49 GHz (relative bandwidth 18.7%). The gain loss of the proposed array is about 0.1 dB compared to the reference array. The monostatic RCS is reduced for dual−linear polarized waves, and the 6 dB radar cross section reduction (RCSR) bandwidths are 62.3% and 35.7%, respectively. The prototype is fabricated and measured. The measured results of radiation pattern and RCS are in good agreement with the simulated results.