RSS-Based DoA Estimation Using ESPAR Antennas and Interpolated Radiation Patterns

In this letter, it is shown how an algorithm, which employs received signal strength values in order to estimate direction of arrival (DoA) of impinging signals in wireless sensor network (WSN) nodes equipped with electronically steerable parasitic array radiator (ESPAR) antennas, can easily be improved by applying an interpolation algorithm to radiation patterns recorded in the calibration phase of the DoA estimation process. The proposed method allows one to measure ESPAR antenna's radiation patterns during the initial calibration phase with much coarser than 1 degrees angular resolution, while the overall DoA estimation accuracy can be kept at the similar level. Measurements using a fabricated ESPAR antenna have indicated that anechoic chamber calibration procedure of WSN nodes equipped with such antennas can be done almost 50% faster, which in consequence will reduce system deployment costs in practical WSN applications where a number of WSN nodes can easily reach hundreds.