A Wideband SSPP-Based Leaky-Wave Antenna Exploiting Quasi-Glide Symmetry for Millimeter-Wave Applications

This article proposes a spoof surface plasmon polariton leaky-wave antenna (SSPP LWA) with independently suppressed open-stopband (OSB) and grating lobe for operation at millimeter-wave frequencies. The main operating section of the SSPP LWA consists of corrugated metallic strips loaded by a periodic arrangement of circular patches exhibiting quasi-glide symmetry, suppressing the OSB on the broadside. The OSB suppression is analyzed by accurately extracting the dispersion characteristic of the SSPP LWA. A theoretical method is proposed to predict the directional radiation patterns of the proposed LWA. Periodic LWAs suffer from the grating lobe at higher frequencies as the main beam scans toward the forward direction. To address this issue, we propose a modification of the unit cell radiation pattern. This increases the gain in the main beam direction while reducing it in the region where the grating lobe appears at higher frequencies. This behavior is achieved by employing asymmetrical slots within the circular patches. The simulated beam scans from -30° to + 46° within a gain variation of 3.8 dB by varying the frequency from 55 GHz to 95 GHz. The simulated radiation efficiency over the entire band is above 77%. The measured beam scans from + 16° to + 48° with a maximum realized gain of 15 dBi in the frequency range of 75 GHz to 95 GHz. The simulated results agree well with the experimental data over a wide operating frequency range. The fabricated antenna on fused silica would be attractive for millimeter-wave radar and imaging systems.