A Full-Space and High-Scanning-Rate Leaky-Wave Antenna Based on Stopband-Suppressed Slow-Wave Transmission Line

This paper presents a novel full-space leaky-wave antenna (LWA) with both a high scanning rate and efficiency based on a stopband-suppressed slow-wave transmission line (TL). By satisfying the frequency-balance condition at the upper cutoff frequency in an odd-mode slow-wave TL, a slow-wave coplanar strip (CPS) with stopband suppression between two transmission modes is proposed, which introduces a new frequency region with a large group delay and good transmission capability. With these characteristics, this slow-wave TL can be used in the full-space LWA to enhance the scanning rate while maintaining a high efficiency. The odd-mode slow-wave unit features a complementary structure, and the frequency-balance condition can be easily satisfied by controlling the size of short-ended slots etched on the CPS and stubs loaded on the bottom layer. By etching open-ended slots on the proposed slow-wave TL, an LWA is designed. With both the CPS gap and open-ended slots contributing to radiation, the proposed LWA realizes the scanning in the horizontal plane. Moreover, bias slits are loaded in the antenna unit to mitigate the open-stop band (OSB). Finally, a prototype of the proposed LWA is fabricated and measured. The LWA realizes the full-space radiation in the horizontal plane and has a high scanning rate (14.85°/%) and high average efficiency (72.4%).