Multibeam Monopulse SIW Slot Array Antenna

摘要： A multibeam slot array antenna is proposed in the 10-GHz band for a monopulse tracking system with resolution enhancement techniques. The antenna architecture combines a four-subarray SIW slot antenna, a multibeam-forming network of microstrip Rotman lens array, and a SIW comparator of four-quadrant monopulse technique. A method to form difference patterns in both E-plane and H-plane for mutibeams is presented, and the method can improve the accuracy of angle detection for all beams. The key point of the method is to compensate the phase difference caused by the beam deflection between two subarrays (quadrants) by constraining input delay lines of the Rotman lens array. To validate the proposed concepts, an antenna prototype is realized and measured. The experimental results demonstrate a scanning range of ±36° with -5 dB crossover level between two adjacent sum beams in the E-plane. The corresponding beams of difference pattern are generated in E-plane and H-plane via the monopulse comparator to enhance angle resolution. The multibeam monopulse system can achieve gains between 21.7 dBi and 23.5 dBi for all sum beams at the center frequency of 10 GHz. The lobe imbalances are less than 1.1 dB and null depths are lower than -16 dB for all difference patterns. This multibeam monopulse slot antenna can be applied in radar and communication systems requiring beam-scanning capabilities and target tracking.