Compact Beam Steerable Antenna Utilizing Tunable Active Metamaterials

Abstract

Applications like mobile communication, radars, satellite communication, and advanced vehicle to-vehicle communication require beam steerable antennas. In radars, beam steering antennas are used to scan and track the intended targets. In contrast to mechanical beam scanning which has inherent disadvantages of slow scanning speed and mechanical failure, electronic beam scanning has been widely adopted in the last decade to provide agile and fast scanning without any moving parts. Conventionally, electronic beam scanning is achieved through transmit/receive modules (TRM) that provide progressive phase shift to different elements of the antenna array thereby switching the beam in the desired direction. Being the key component in radar, TRMs dominate the overall cost and size of the radar. This research focuses on studying and implementing alternative phase shifting mechanisms directly implemented in the antenna arrays avoiding the need of TR modules. The use of electronic switching components such as PIN diodes are explored to design a tunable active metamaterial in conjunction with substrate integrated waveguide (SIW) technology to achieve the desired phase shifts. This combination in the form of an array could be seen as a metamaterial capable of beam scanning both in elevation and azimuth. A hybrid mechanism of phase control for beam steering is proposed, that is for beam switching in EL plane, PIN diodes provide the required phase shift, and an external phase shift is used to steer the beam in AZ plane. The proposed antenna design gives improved side lobe levels (-16dB to -10dB), beam steering of -27° to +34° in EL plane and ±25° in AZ plane with maximum gain of 15.2dBi.