Design and Implementation of Wideband Monopulse Comparator Based on Inverted-Microstrip Gap Waveguide Technology

Microwave devices using printed gap waveguide technology, such as inverted microstrip gap waveguide (IMGW), are essential for millimeter-wave applications. In this article, a new wideband monopulse comparator composed of four wideband rat-race hybrid couplers is proposed. The complete theory behind the couplers is presented using even-odd mode analysis. To demonstrate the potential of the proposed monopulse comparator, the structure has been designed, fabricated, and measured. Measured results show a bandwidth of nearly 50% for a reflection coefficient of better than 10 dB, an isolation of better than 27 dB between the ports. There is an imbalance of −1.25/+0.25 dB and 2.5° in magnitude and phase at the output ports, respectively. The measured results show that the phase and power dividing performance between output ports is satisfactory across the entire frequency range.