ISAR imaging using circularly polarized antennas in an anechoic chamber

Synthetic aperture radar (SAR) imaging is typically performed using linearly polarized (LP) signals. There are not many SAR systems utilizing circularly polarized (CP) signals. Recent trends show investigation into CP such as Compact SAR resulting in reduced system size and images with distinct characteristics due to CP signals. To gain insight into a full CP SAR system, we begin study in a controlled environment. This paper presents the design and testing of a wideband inverse synthetic aperture radar (ISAR) system using CP antennas for both receive and transmit. Data measurement setup was constructed in an anechoic chamber with the use of a vector network analyzer (VNA) and automated rotary turntable to revolve targets. We present the measurement procedures for CP imaging, followed by imaging results of canonical targets made using uncalibrated data for CP and compared them with LP ISAR images to illustrate the differences between the two polarizations. This work will lead to the investigation of generating images from CP receive and transmit signals, CP polarimetric decomposition, improvement of related imaging algorithms for CP signals and suitable antenna design.