Sidelobe level reduction in pattern synthesis of a non-uniform series-fed microstrip antenna array using the TLBO algorithm

In this paper, a series-fed microstrip patch antenna array with high gain and extremely low sidelobe levels, operating at 24 to 24.25 GHz, is presented. This antenna is fabricated on a single-layer PCB substrate. Due to its features such as compactness, lightweight, low cost, high gain, and narrow beamwidth, it can be used in many applications such as perimeter surveillance and collision-avoiding radar systems. The proposed antenna is a rectangular antenna array that consists of a non -uniform linear array with 50 in-line series-fed elements in one dimension and a uniform linear array with 16 elements in the other dimension. The non -uniform array provides 78% more physical space between the central elements, which is used to place the feed network of the uniform array. The radiation pattern of this non -uniform array has been synthesized using the TLBO algorithm. The prototype antenna with dimensions of 335 mm x 120 mm has been fabricated and tested. The measured gain of this antenna at central frequency is 28 dBi, with a 3 -dB beamwidth of 2.6 and 7 and sidelobe level of 23.3 and 22.5 dB in the E-plane and H-plane respectively.