A <i>Ka</i> -Band In-Vehicle Antenna With Intelligent Beam Steering for V2S Communication

A vehicle-to-satellite (V2S) leaky-wave antenna (LWA) system with intelligent beam steering characteristic for Ka-band V2S communication is proposed, integrated with perception, computation and communication. The framework consists of three parts: a periodic leaky-wave antenna with circular polarization (CP) for communication with the satellite, a perception unit for computation of the azimuth angle of the satellite with respect to the antenna, and a decision making unit for intelligent beam steering. First, a groove gap waveguide (GGW) with serrated ridge is developed for a slow-wave transmission, and then the radiation array on the top layer of the antenna is designed with each unit excited by a coupling slot, which is independently and electrically controlled by the biasing of the PIN diodes with “on” and “off” operation states. Thus, a CP period-reconfigurable antenna with total 25 steerable beams is developed. Second, the Global Positioning System (GPS) is used to acquire the values of the latitude and the longitude, both for the in-vehicle antenna and the satellite, and the azimuth angle of the satellite with respect to the antenna is then figured out by coordinates transformation. Finally, the azimuth angle is matched to a certain sequence of the operation state of the antenna, where a Field Programmable Gate Array (FPGA) controlling module with all 25 states precoded is used to make decisions regarding the biasing of the PIN diode array, to achieve a steerable beam pointing. Thus, a CP leaky-wave antenna with intelligent beam steering is realized. Both simulated and measured results indicate that this proposed antenna has good performance both on the transmission properties and the radiation properties, with a CP band from 30 GHz to 33 GHz, a peak gain of 18.2 dBi, an average radiation efficiency of 89% for 25 operation states, and a wide-angle beam-scanning from 84∘ to 900 during the observation band, which is especially a promising candidate for Ka-band V2S communication application.