A Broadband Multilayer Magic-T Using Coupled Microstrip-Slotlines for Monopulse Antenna Systems

In this paper, a broadband multilayer planar magic-T using coupled microstrip-slotlines is proposed. Sum and difference function in this design are realized by utilizing the even and odd transmission mode of the coupled microstrip-slotlines. The magic-T is conducive to the miniaturization of monopulse antenna systems by using a 3-layer circuit board structure and reasonable port placement. Simulation results show that the operating frequency range is 1.25-2.52 GHz with return loss higher than 10 dB, while in-band isolation between sum and difference port is greater than 50 dB. It also has amplitude and phase imbalance of less than 0.1 dB and 0.4° respectively.