Compact Ku-Band Monopulse Comparator Using Offset Two-Step Rectangular-Prism-Based Magic-T

초록

This paper presents a compact Ku-band monopulse comparator with enhanced inter-port balance and isolation. The key component, a magic-T, was designed using an offset two-step rectangular prism and an iris to improve impedance matching and isolation while maintaining ease of mechanical fabrication. The magic-T, fabricated as a two-split block, achieved a return loss > 15.0 dB over 13.9-15.6 GHz, with insertion loss < 0.3 dB, amplitude/phase imbalance < 0.05 dB/0.5 degrees, and isolation > 45 dB. A monopulse comparator was developed using four magic-Ts, connected symmetrically to maintain balance among the output ports. To reduce reflections in the H-plane bends necessary for constructing the comparator, chamfered bends were employed. The monopulse comparator, fabricated as a six-split block, achieved a return loss > 13.0 dB across 14.1-16.1 GHz at all ports, insertion loss from the input to each output port (one sum and two difference ports) was less than 0.5 dB. The amplitude and phase imbalances were less than 0.1 dB and 1.7 degrees, respectively, with the isolation > 50 dB. These results demonstrate superior performance compared to previously reported monopulse comparators.

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