Ultra-wideband radar cross-section reduction for ring-shaped microstrip antenna based on characteristic mode analysis

In this letter, a characteristic mode analysis method is presented for ultra-wideband radar cross-section (RCS) reduction of microstrip antenna. By analyzing the magnitude of the modal weighting coefficients (MWCs), the important scattering modes can be found, which contribute a lot to the RCS of the antenna. Then, these scattering modes are suppressed through shape modification. To realize an ultra-wideband RCS reduction (RCSR) of a ring-shaped microstrip antenna, three pairs of slots are placed at suitable locations of the reference antenna to disrupt the current path, so as to suppress the important scattering modes while keeping the radiation modes work properly. Compared to the reference antenna, the proposed antenna achieves 6 dB RCSR on average over the frequency band of 0.5 GHz-5 GHz (163.64%) for x-polarization incident wave. The peak reduction at 3.0 GHz is up to 23 dB. Meanwhile, the radiation performance keeps well. The measured and simulated results are in good agreement, which validates the presented method.

Automated summary

The study presents a characteristic mode analysis method for ultra-wideband RCS reduction of microstrip antenna. By suppressing important scattering modes through shape modification and disrupting current paths by placing slots at suitable locations, the proposed antenna achieves an average of 6 dB RCSR over a wide frequency band, with a peak reduction of up to 23 dB at 3.0 GHz while maintaining good radiation performance. The measured and simulated results confirm the effectiveness of the proposed method.