Design of a Leaky-Wave Antenna Featuring Beam Scanning From Backfire Utilizing Odd-Mode Spoof Surface Plasmon Polaritons

In this communication, a leaky-wave antenna (LWA) featuring beam scanning from backfire direction is investigated. The presented LWA is designed based on the odd-mode spoof surface plasmon polariton (SSPP) waveguide that consists of a row of complementary "cross-shaped" units. The odd-mode SSPP is excited by a convertor from the microstrip line to the slotline. As opposed to the even mode, the equivalent electric current of the odd-mode SSPP is perpendicularly distributed to the longitudinal direction, providing a complete backfire radiation component. Then a general method to design a sinusoidally modulated reactance surface (SMRS) LWA is introduced to efficiently generate backfire radiation at desired frequency and the depth of each SSPP unit is determined by calculation. By this way, the optimized working of the LWA will be drastically reduced. A prototype of the presented LWA is simulated, fabricated, and measured. Simulation and experimental results show that the main beam of the presented LWA scans from backfire at desired frequency of 20 GHz to the broadside direction at 27.5 GHz. And the antenna shows bidirectional radiation feature.