Design of Broadband and Ultra-Wide-Angle Low-RCS Open-Ended Cavity Based on Phase Cancellation

In this paper, it is proposed to employ phase cancellation metasurface (PCM) to substantially reduce the RCS of an electrically large open-ended cavity (EOC) by scattering the energy to the nonthreatening region, achieving broadband and ultra-wide-angle RCS reduction of the cavity. The PCM, constituted by the collection of polarizing reflectors, is loaded on the inner and outer walls of the composed cavity structure in accordance with the orthogonality principle to obtain a low-RCS cavity. The main benefits of using the polarizing reflector to build a PCM are as follows: On the one hand, it reduces the number of units that make up the PCM, which in principle only requires half of the quantity. On the other hand, it is possible to form a phase difference of 180 degrees that is completely stable. Both the simulation and measured results show that the RCS reduction of 10 dB for normal incidence relative to the original state of the cavity (that is, the metal cavity) over a frequency range of 6.3 GHz to 13.2 GHz under TE polarization and 7.8 GHz to 13.4 GHz under TM polarization has been obtained. Furthermore, the RCS reduction performances of the cavity loaded with the composed PCM under variable azimuth angles are also studied. Numerical and experimental results demonstrate that the ultra-wide-angle RCS reduction from -180° to 180° is acquired. To the best of our knowledge, this is the first time that the PCM, which is made up of a number of polarizing reflectors, has been used to get broadband and ultra-wide-angle RCS reduction for the EOC. This method, which is simple, effective, and low cost, has great application prospects in the RCS reduction design of the cavity.