Simple Approach to Measure Angle of Arrival of a Microwave Signal

A new photonics-based microwave angle of arrival (AOA) measurement system is presented. It is based on a single-laser, single dual-drive Mach Zehnder modulator (DDMZM) and single-photodetector structure. The AOA of a microwave signal can be determined by simply measuring the system output DC voltage. The proposed system is suitable for determining the AOA of a microwave signal with a single frequency or a band of frequencies, and has a wide AOA measurement range. Experimental results are presented that demonstrate an AOA measurement range of 0° to 76.8° and 12.6° to 90° without and with introducing a time delay to one of the DDMZM input RF ports respectively, and measurement errors of less than 2°. Results also demonstrate an AOA measurement for a pseudorandom binary sequence signal upconverted into a microwave frequency.