Design & development of a 32 elements X-band Phased Array antenna for airborne & Space borne SAR payloads

Abstract

Air Borne & Space Borne SAR Payloads are used now a days in variety of missions for different applications. Onboard SAR payload consists of a digital signal processing & data storage unit, a transceiver and an antenna unit. Onboard antenna is a vital unit of a communication system and design of antenna becomes much more critical and complex once electronic beam steering is an essential requirement. Usually for SAR applications, electronically steerable high gain antennas are required to support different operating modes. In this paper, design of 32 elements X-band Phased Array is discussed along with its simulation and measurement results. Design antenna is based on microstrip technology and orientation of feeding mechanism to a certain group of elements is such that it provides circular polarization both across range/azimuth. Electronically steering is possible by changing the phase at the inputs of the antenna ports and different possible steering scenarios are discussed in this paper. An advanced EM simulation software is being used for design and simulation purpose. Simulated results provide a gain of approximately 20 dB with a VSWR <; 2 at desired frequency range in the band. Axial ratio of <; 3 is targeted and achieved in the desired frequency range.