A Novel ۷۰ GHz Circularly Polarized Fully-Planar Leaky-Wave Antenna with X-shaped slots for Millimeter-Wave Radar Applications

This paper presents a novel, fully planar circularly polarized periodic leaky-wave antenna (CP-PLWA) designed for wide-beam scanning in the ۷۰ GHz band for millimeter-wave radar applications. A complementary split ring resonator half-mode substrate integrated waveguide (CSRR-HMSIW) feed structure is employed, offering a low-loss, and readily manufacturable implementation. The key innovation is the integration of cascaded X-shaped slots within the radiating patch, which facilitates controlled surface current perturbation and optimized excitation of orthogonal E-field components, resulting in a significantly enhanced circular polarization bandwidth. This design enables backward-to-forward beam scanning while maintaining a fully planar, via-free architecture. Simulated results demonstrate a ۲۰.۱% impedance bandwidth (۶۴.۴–۷۷.۷۵ GHz), an axial ratio bandwidth exceeding ۱۳.۶% (۶۶–۷۵ GHz, AR < ۳ dB), and a wide scan angle from –۱۵° to +۶۰°. A gain exceeding ۱۳ dBi (peaking at ۱۶ dBi) is achieved with a simulated radiation efficiency greater than ۹۷%. This compact, fully planar design, fabricated on a Rogers RT/duroid ۵۸۸۰ substrate, advances the state-of-the-art in CP LWAs for ۷۰ GHz millimeter-wave radar systems by simultaneously addressing critical limitations of prior art: achieving wide CP bandwidth in a planar configuration, eliminating fabrication-via complexity, and maintaining high efficiency across a wide scanning range. The proposed antenna offers a promising solution for future high-performance radar applications requiring compact, wideband, and frequency-scanned circularly polarized radiation.

کلیدواژه ها:

Circularly-Polarized (CP) ، Leaky-Wave Antenna (LWA) ، Half-Mode Substrate Integrated Waveguide (HMSIW) ، ۷۰ GHz band ، Wide-Beam Scanning ، Planar ، metamaterial ، CSRR