Experimental Direction Finding Results Using a Time-Multiplexed Co-Array Approach

This paper addresses the problem of multi-source direction finding with a system that employs fewer receiver channels than antenna elements. To verify previous theoretical work [1], an experimental sensor system was built up and used for measurements in an anechoic chamber. The system consists of a specifically arranged (co-)array antenna divided into a 6-element uniform circular prototype array coupled through a switch to one receiver channel, and two directly connected reference antenna elements. Experimental results show that time-multiplexed (switched) direction of arrival estimation with number of sources equal to the number of receiver channels is feasible. Therefore, co-array techniques are utilized at each switch position and the received signal covariance matrix of the prototype array is reconstructed by means of spatial smoothing. The combined switched co-array approach is compared to the standard time-multiplex method in the sense of direction finding and source identification capability. Furthermore, direction finding results of a full 8-channel receiver system with the same array antenna used to span the co-array geometry are presented and discussed.