Multidimensional ambiguity functions of linear, interferometer, antenna arrays

Greater insight into the resolution and accuracy, as well as the data processing, of an interferometer radar is obtained in this partly tutoral paper by the examination of the multidimensional ambiguity function. Two approaches are used for determining the multidimensional ambiguity function. First, it is determined by the classical and more standard procedure in which the signals at the target and at the receiver antenna output terminals are found by the superposition of the signals of each antenna array element. The second method considers the antenna as a network having a specified frequency transfer characteristic which is dependent on the azimuth spatial coordinate of the target and on the axis of the antenna beam. Prime consideration is given to signals having large time-bandwidth products and wide bandwidth. Extensive plots are made for the multidimensional ambiguity function of the linear, interferometer, antenna array system. The analysis verifies the previously obtained result that the grating lobes of an interferometer radar can be eliminated by the use of very wide band signals. The results also show that a trade off can be made between the signal bandwidth and the number of array elements in order to achieve a specified sidelobe level. Furthermore, it is found that increasing the spacing between the array elements results in an improvement in the angular accuracy and resolution in direct proportion to the increase in spacing. This improvement is accrued without degradation in the estimation of the other target parameters or in detectability.