Multistatic Microwave Synthetic Aperture Radar (SAR) Imaging Using Orthogonal Binary Coding

The utilization of orthogonal binary phase shift keying (BPSK) modulation in a microwave synthetic aperture radar (SAR) imaging system is a novel technique that reduces the complexity of system hardware and expedites the measurement process for large imaging arrays. BPSK techniques are commonly used in ranging and communications, where transmitting multiple signals without interference is important. This methodology can also be applied to multistatic SAR imaging, allowing an imaging array to simultaneously gather data from all transmit/receive pairs. These measurements can then be processed with a robust SAR imaging algorithm, resulting in real-time generation of 3D images for a variety of applications including those involving nondestructive testing (NDT). Current array-based imaging techniques utilize switch-based or frequency offset designs. These designs suffer from increased hardware complexity, and in the case of switch-based systems, longer measurement times. Utilizing orthogonal coding techniques allows an array to transmit and receive from many elements simultaneously, which reduces measurement time and simplifies system hardware, since the codes are generated and processed in software. This paper discusses the theory behind the proposed imaging technique and shows a proof of concept system that was used to create microwave SAR images of targets.