Periodic Leaky-Wave Antenna Based on Complementary Pair of Radiation Elements

In this paper, we propose and develop a leaky-wave antenna (LWA) by periodically loading shunt radiation element pairs along a host transmission line (TL). Each pair of radiation unit consists of one capacitive element and one inductive element, which are susceptance-complementary with each other. The complementary radiation element loading leads to an effective open-stopband (OSB) suppression, thereby facilitating a continuous leaky-wave beam scanning from backward, through broadside, to forward. Compared with the previously studied OSB-suppressed LWAs containing only one type of susceptive radiation elements, the proposed LWA features two unique properties: constant radiation efficiency over the operation band, and unit cell period only related to the host TL regardless of parameter values of the radiation elements. The aperture synthesis of the proposed LWA is hence straightforward as the radiation elements can be designed to be equally spaced. Experimental prototypes are designed and fabricated based on microstrip line structure as a proof of concept. Desired measured results agree well with the theoretical predictions.