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 degrees 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.