A Compact Dual-Band Dual-Polarized Microstrip Antenna Array for MIMO-SAR Applications

This paper presents a compact dual-band dual-polarized microstrip antenna array with wide bandwidth and low profile for multiple-input multiple-output (MIMO) synthetic aperture radar-imagery applications where both high resolution and portability are required. This array has a stacked structure, consisting of two shared-aperture dual-band orthogonal-polarized sub-arrays with high isolation. Each pair of driven patches for the two-band shares two parasitic patches to achieve compactness. Slits are etched on the shared parasitic patches to adjust the coupling frequency between two elements of the two bands. The defected ground structure integrated in the array effectively suppresses H-plane cross-polarization. A 4 x 6 array as an MIMO element sized of 77 mm x 79 mm x 2.2 mm has been fabricated and tested. Both wide beamwidth and stable gain are achieved, where the impedance bandwidth of 27.7%, 30.6%, 15.6%, and 23.8% in X-band vertical, X-band horizontal, Ku-band vertical, and Ku-band horizontal polarizations, respectively.