Circularly Polarized Array Antenna for Polarimetric SAR Application

In this letter, the design, simulation and measurement of a novel circularly polarized array antenna for polarimetric synthetic aperture radar (PolSAR) applications in the C-band are presented. A low-cost and compact solution is achieved by employing microstrip technology. More precisely, a multilayer configuration is adopted, where the sequential rotation technique, combined with the use of slotted parasitic elements in a stacked arrangement, ensures wideband operation and high polarization purity. The proposed array antenna exhibits compact dimensions (62 mm × 62mm × 13mm) with low weight of only 56 g. Measurements performed on a fabricated prototype show that the$|S_{11}|$parameter remains below -10 dB from 4.82 GHz to 7.62 GHz (corresponding to a 45% bandwidth), with the axial ratio below 3 dB from 4.95 GHz to 6.85 GHz (corresponding to a 32% bandwidth), which is fully encompassed by the impedance bandwidth. Moreover, the measured far-field patterns in the anechoic chamber are in excellent agreement with the simulated results. Hence, the proposed array antenna represents a promising candidate for PolSAR systems, where challenging radiation requirements coexist with stringent compactness constraints.