A Wideband Low-RCS Circularly Polarized Reconfigurable C-Shaped Antenna Array Based on Liquid Metal

A wideband low radar cross-section (RCS) circularly polarized (CP) reconfigurable patch antenna array based on liquid metal (LM) has been proposed in this article. The array was formed by $4\,{\times }\,4$ CP C-shaped antenna elements fed with a sequential feeding network. The antenna element was designed with a pair of narrow slots, and a microchannel adhered to the top metal layer. The CP reconfiguration depends on the tuning of the slots by moving the LM in the channel. The patch antenna array can obtain good CP radiation and low RCS features without any extra RCS reduction structures other than the array elements. RCS reduction (RCSR) can be realized by $180^{\circ }\,{\pm }\,37^{\circ }$ reflection phase variations between two different antenna elements under normal incidence for both $x$ - and $y$ -polarizations. The antenna prototype has been fabricated and measured. The measured results show good agreement with simulated results.