Design of compact X-band 128 elements microstrip patch array antenna for airborne and space borne SAR applications

Microstrip Patch Array Antennas are widely used nowadays in radar satellite and other communication Systems. Use of Microstrip array as Synthetic Aperture Radar (SAR) is wide-spread these days in Airborne as well as Space Borne SAR missions. In this paper, design of a compact 128 elements Microstrip Antenna Array is discussed operating in X-Band. Designed array is high gain with total 128 radiating elements in configuration of 2×4 sub-arrays. 16 elements are single fed and constitute a single sub-array. Elements are excited using corporate feed network and have inter-element spacing of 0.6λ. Microstrip array is designed using commercially available low-loss dielectric substrate Rogers having relative permittivity ϵ
_r
=2.2, thickness 1.575 mm and loss tangent 9 × 10
^-4
and simulated using Advance EM Simulator. Simulated gain of single sub-array is 17 dB while complete array has gain of 26 dB. Return Loss or S
₁₁
of array is less than -50 dB which proves that designed array is matched to input impedance of 50Ω. As Array is in form of 2×4 sub-arrays having total 8 inputs, it can be used effectively for electronic beam steering by changing phases at input ports. Designed array is manufactured using highly precise PCB manufacturing facility and testing using far-field testing facility. Measured results are in close conformance with the simulated results.