A Mesh-Type Ultrawideband Low-RCS Transmitarray Antenna Based on Spoof Surface Plasmon Polariton

In this letter, an ultrawideband low radar cross section (RCS) transmitarray antenna is designed, which is composed of a microstrip antenna array and a transmissive metasurface based on spoof surface plasmon polariton (SSPP). The mesh-type transmissive metasurface, which consists of 4 × 4 double-cross SSPP elements, can achieve transmitting electromagnetic waves in the X-band and reduce RCS on both sides of the passband. In addition, the reflection phase difference between two adjacent elements can be regulated by the height of the SSPP structure. Thus, by means of a checkerboard array, the transmissive metasurface can scatter normal incident waves to achieve RCS reduction. Moreover, when the transmissive metasurface fed by the microstrip antenna array, good radiation performance can be achieved in the X-band. The experimental results show that the maximum gain of the transmitarray antenna is 18.6 dBi and the 3 dB gain bandwidth is 9.7–10.7 GHz. Compared with the original microstrip antenna array, the transmitarray antenna achieves RCS reduction in the ultrawideband of 4.7–12.2 GHz, with a maximum reduction of 11.98 dB and a relative bandwidth of 88.8%. Meanwhile, RCS reduction performance is still good under oblique incidence.