ESTIMATION OF DOA USING AN ARRAY OF YAGI ANTENNAS IN THE UHF BAND USING AN INTERPOLATION TECHNIQUE

In this paper we present a methodology using an interpolation technique for estimating direction of arrival (DOA) and other parameters of the incoming signals for different frequencies. The interpolation technique allows to take into account the mutual coupling between the elements of the array to improve the reliability of an adaptive process in a real environment. An array of Yagi antennas in UHF band is used to illustrate the method. INTERPOLATION TECHNIQUE The procedure is based on transforming the real data of the array into an uniformly linear spaced virtual array, called ULVA (1) in order to compensate the effect of the mutual coupling between the elements of the array. We store the voltages induced in the elements of the real array in a single snapshot in a matrix called (A) due to an incident wave coming from a particular direction. This matrix (A) can be generated either from measurements or from numerical simulations using an electromagnetic simulator like WIPL-D (2). On the other hand we build a matrix (B) that consists of the voltages induced in a uniformly spaced virtual array of omni directional point radiators placed in a region spanned by the original real array. Now, we can find a transformation matrix (T) which will convert the induced voltages in the real array (A) into the voltages of the virtual array (B). This interpolation matrix is independent of the angle of the incident wave and will be used to correct the effect of undesired electromagnetic effects.