Compact Series-Fed Monopulse Antenna Array Based on Multi-feed Technology

A compact multi-feed monopulse antenna array is proposed in this paper. An equivalent circuit and the theory of multi-feed antenna array are developed to analyze the array factor of the sum and difference beam. A close agreement between the calculated and electromagnetic simulated radiation pattern is observed. By controlling the magnitudes and phases of multiple excited ports, the desired sum beam and difference beam can be achieved. Different from the conventional four-quadrant symmetrical layout, only one subarray is employed to realize monopulse antenna array. In comparison with the conventional single-feed monopulse antenna array, the beamwidth of the sum beam in the proposed multi-feed antenna array is almost twice as wide, and the circuit size of the multi-feed antenna array is also reduced by half. Without increasing the antenna array panel size, the function of low-loss on-antenna power combining is achieved in the proposed multi-feed antenna array. Meanwhile, the need for a power combiner and passive impedance matching network is eliminated. Moreover, the results show the effective isotropic radiated power (EIRP) of transmitter system with the proposed multi-feed antenna array exhibits an increase by 10 × Log₁₀(N) (N ≥ 3) dB. The proposed multi-feed monopulse antenna array paves the way for the development of miniaturized mid-and long-range monopulse radar system.