DOA error estimation using 2.6 GHz DBF array antenna

The DOA (Direction Of Arrival angle) estimation errors due to hardware problems are investigated experimentally using a four-channel DBF array antenna system operating at the 2.6 GHz IMS band. The DOA estimation by the MUSIC (MUltiple SIgnal Classification) algorithm is examined inside a radio anechoic chamber to clarify the estimation error mechanism. The purpose of this paper is to estimate the DOA correctly for all arrival directions. To examine the error in detail, the estimation error has been measured in the case of one transmission source, and the error is ±12 degrees without any corrections. We investigated these error factors and found two major factors: the inaccurate interval of array elements and the mutual coupling between the elements. By compensating these errors using the mode vector measured correctly, the error was reduced to ±3 degrees. In addition, when the mode vector, measured at intervals of up to 20 degrees, is interpolated by the spline interpolation method, the estimation error is restrained within ±5 degrees.