A Wideband 1-bit Reconfigurable Electromagnetic Surface for Monopulse Radar Applications

Abstract

We present a wideband 1-bit reconfigurable electromagnetic surface (REMS) for monopulse radar applications at X-band. The proposed REMS element integrates a 1-bit reflection-type phase shifter (RTPS) controlled by a p-i-n diode. By altering the working states of the p-i-n diode, well-defined beam scanning is obtained. Furthermore, selecting different feeding states can realize the sum ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Sigma$ </tex-math></inline-formula> ) and difference ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Delta$ </tex-math></inline-formula> ) patterns. The key design issues, including element modeling, coding design, and feed optimization, are studied to obtain good <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Sigma $ </tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Delta $ </tex-math></inline-formula> beam performance. Experimental results show that REMS achieves a high gain of 23.3 dBi, a low sidelobe level of −15 dB, and a low null depth of −30 dB. The wide-angle monopulse beam-scanning up to ±60° is obtained. The gain bandwidth of −3 dB ranges from 9.35 to 11.75 GHz, with a relative bandwidth of 22.75%. Thus, the proposed multifeed REMS brings new freedom for the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Sigma $ </tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Delta $ </tex-math></inline-formula> beam scanning, which provides wide application prospects for the monopulse radar system.