An optimum side-lobe reduction method with weight perturbation

Generally, the phased antennas used in radar and communication systems have a certain taper to minimize the side-lobes. However, most tapering methods are inefficient for practical applications because they generally reduce the overall efficiency of the system. It is therefore necessary to develop improved methods for reducing the side-lobes, especially for future fifth-generation (5G) communication systems, whose performance is expected to be drastically limited by interfering signals. Two new methods for obtaining low side-lobes with very little loss in directivity are presented herein. In both methods, the excitations of the elements in a uniformly excited array are perturbed such that the corresponding array factor constructs a specific cancellation pattern. The cancellation pattern in the first method is constructed using a simple analytical procedure, whereas in the second method it is constructed using a more powerful optimization algorithm. The cancellation patterns of both proposed arrays are then independently subtracted from the original, uniformly excited arrays to obtain new array patterns with deep side-lobe reduction. The simulation results show that the directivity differences between the two proposed arrays and the uniformly excited array decrease as the number of array elements is increased; For example, when considering an array with 100 elements, the directivity difference is only 0.1435 dB. Moreover, the proposed arrays can reduce the peak side-lobe levels by more than 27 dB compared with the corresponding uniformly excited arrays.