A new broadband uniform accuracy doa estimator

Conventional estimators of the bearing angle suffer from different accuracies for different angles. In the method discussed in this letter, a set of two-dimensional digital filters are employed for beamforming. Each filter is called a fan filter and performs broadband characteristics. It will be shown analytically that the accuracy of the bearing estimation is strongly dependent to the angle of arrival in such a way that it is maximum in the broadside and minimum in the endfire of the antenna. We will derive a simple expression for calculating the number of coefficients necessary for beamforming with uniform accuracy. A set of filters is then designed according to this criteria. It will be demonstrated by computer simulations that in the presence of noisy broadband incoming signals, the estimation of different arriving angles is accomplished with almost the same accuracy and hence using this method a complex and separately sectored antenna wilt not be required.