K_u-band circularly polarized leaky-wave antenna based on lateral sparse substrate integrated waveguide for satellite communication

This paper presents a user terminal leaky-wave antenna (LWA) for satellite communication system in Ku-band. The motivation is to propose a low-profile broadband high-gain receiving antenna with beam-scanning and circular polarization features. The antenna is based on a lateral sparse substrate integrated waveguide, which is constructed by a microstrip line shorted with two rows of sparse and abundant periodic metallic via-holes on both sides with periodic transverse slots etched on the upper side. To achieve good circularly polarized radiation and compact configuration, non-uniform SIW width configuration is used to realize effective phase shift over the relative broadband. Measured results show that the antenna presents experimentally expected broadband matched impedance with return loss |S₁₁| > 10 dB from 15.4 GHz to 19 GHz. The measured radiation pattern exhibits continuous frequency-scanning from 35° at 15.5 GHz to 47° at 18 GHz according to the broadside with maximum gain of 12.3 dBic. The measured axial ratio is within 3 dB from 15.9 GHz to 17.2 GHz. Measured results are in good agreement with predicted ones, and it is demonstrated that the proposed structure is a simple and compact candidate of high performance circularly-polarized antenna for satellite communications. Also the beam scanning capability of proposed antenna could find potential applications in inter-satellite communications.