A 2x4 microstrip antenna array for monopulse tracking radar at S-band

This paper proposes a 2x4 microstrip antenna array for mono-pulse tracking radar in the S-Band. In the proposed design, a rat-race coupler is paired with a 2x4 patch antenna array at 3GHz. The feed is given to the sum and difference ports of the rat-race coupler to obtain the sum and difference patterns. The design aims to help in tracking. The tracking is done in one-dimensional space, and the design has limited elements with better efficiency. In the proposed design, the simulated and measured results have a return loss of at least - 10 dB at 3 GHz and the sum pattern has a main lobe and side lobe difference of at least 12 dB, while a null depth of at least 20 dB is achieved in the difference pattern. A gain of 17 dB has been noted. The simulation of this design was done on Ansys HFSS and MathWorks Antenna Toolbox softwares with an epsilon value of 2.2 of the Rogers RT 5880 substrate with a thickness of 1.6 mm. The design also contains chamfered elements to decrease the side lobe levels.