Design of a switched beam antenna with 360° multibeam steering and omnidirectional capabilities for S‐X band datalink communications

Abstract

In this article, a switched beam antenna (SBA) operating in 360° multibeam azimuth steering and omnidirectional coverage modes is designed and investigated for point‐to‐multipoint datalink communication system. The SBA with a compact size of 342 mm (diameter) × 163.5 mm (height) is composed of two vertically stacked parallel‐plate cylindrical Luneberg lens antennas (CLLAs) with a low‐profile inverted‐cap shaped printed monopole placed above them. Each CLLA yields multiple highly directive beams and 180° scan coverage by implementing an arc feed array of 11‐element Vivaldi antennas at the periphery of the lens. A total of 22 fixed high‐gain beams and an omnidirectional pattern can be selected individually to scan in and cover the azimuth plane. Moreover, the desired refractive index of the lens is controlled through the asymmetric Bruggeman (A‐BG) effective medium theory and realized by using air‐filled holes of different sizes/density in a homogeneous polyethylene base. The simulated and measured results indicate that the SBA exhibits a wide impedance bandwidth over 2.5‐13 GHz, and it also possesses a 360° multibeam scanning performance with about −3 dB average crossover and tolerable gain drops over 3.5‐10 GHz band, while maintaining an omnidirectional coverage with measured gains between 0.7 and 2.7 dBi over 2.5‐8.5 GHz band.