Reduction of Grating Lobes Due to Dividing the Array into Uniform Subarrays Using Genetic Algorithm

Document Type : Original Article


1 Lecturer Assistant, BHIT, Benha University.

2 Egyptian Armed Forces, Egypt.


The total cost of the large arrays can be solved by dividing the array into contiguous subarrays with amplitude and time delay devices at subarray level. This cause appearance of grating lobes when the beam has been steered to small angle away from broadside named grating lobes due to uniform subarrays. These grating lobes caused by the periodicity and the larger spacing between subarrays. If there is a need to steer the main beam at angle that will be small (limited scan), some methods are used to reduce these grating lobes. These methods will be optimized using genetic algorithm implemented using MATLAB. Two approaches used to disrupt the periodicity in the array, so reduction of the grating lobes can be achieved. Three parameters are optimized simultaneously, the amplitude weighting at the subarray ports; the number of elements per subarray and the spacing between elements. The results show that the two approaches reduce the grating lobes upto -9.8 dB for the first approach and -14.6 dB for the second approach, when steered over small-scan angles, up to 15° from broadside, after this range grating lobe will appears again and cannot be reduced.