Compact High Gain Leaky-Wave Antennas Based on Substrate Integrated Waveguide TE220 Mode

In this paper, novel compact high gain broadband leaky-wave antenna (LWA) using TE220 high-order mode is proposed. The high-order mode antenna not only possesses more compact structure with higher gain, but also simplifies the feeding network of the antenna array and relaxes processing tolerance. The radiation element consists of an SIW cavity etched with 2×2 slot array on the top surface, which is excited by a microstrip-slot coupling structure. Microstrip spoof surface plasmon polariton (SPP) is worked as a slow-wave transmission line (TL) to increase the beam scanning range of a four elements periodic array antenna. The antenna was simulated, optimized and fabricated, which verified theoretical analysis. Experimental results show that the linearly polarized (LP) beam scanning antenna has a bandwidth of 53.5% (from 12.6 GHz to 21.8 GHz) with beam scanning range from -24° to +32° and gain in the range of 10.2 dBi to 12.4 dBi. Then a linear-to-circular polarization converter is loaded to implement a circular polarization (CP) beam scanning antenna. The proposed antenna has the features of compact size, low profile, high gain, large beam scanning range and flexible polarization conversion.