Antenna Array for Ku-Band MIMO GB-SAR

A new multi-input multi-output (MIMO) antenna configuration with wideband and low sidelobe level (SLL) is introduced for ground-based synthetic aperture radar (GB-SAR). The proposed MIMO antenna has 15 transmitting and 16 receiving antenna arrays, arranged in two parallel straight lines, to synthesize a virtual array of 256 elements suitable for monitoring relatively large areas. The inter-element spaces are optimized to λ between transmitting elements and 4λ between receiving elements, to realize both low mutual coupling and an inferior SLL of lower than -37 dB for the overall MIMO antenna. The MIMO antenna element has eight rectangular patch linear arrays working at 17.1 GHz. A traveling wave-feeding network with center excitation is used to feed each element, in order to reduce the SLL and achieve a wide bandwidth of more than 300 MHz. The antenna array shows a gain of 14.3 dBi and half-power beamwidths (HPBWs) of 10° and 105° in the elevation and azimuth planes, respectively. The performance of the proposed design satisfies the GB-SAR requirements, which are validated by fabrication and measurement.