Direction of Arrival Estimation for Retrodirective Rotman Lens Antenna Array

A retrodirective array based on simplified direction-of-arrival estimation algorithm is presented. A beamforming network based on Rotman lens providing the direction of arrival estimation as well as the beam steering is proposed. Retrodirectivity is provided by analysing an interrogating pilot signal, which allows retrieving a data to estimate the source position and then steering a beam in response of a pilot signal. The proposed retrodirective array test system was fabricated and measured for operation at 5.85 GHz central frequency. Designed retrodirective Rotman lens-based antenna array forms eight beams with beamwidth of 10° to cover the scanning angular range from -40° to 40°. The evaluation of the direction of arrival by measuring the power level of the received signal depending on the port index for the different angle of incidence of the pilot signal source is experimentally demonstrated. (paper)