@ARTICLE{ iet:/content/journals/10.1049/el.2017.2647, author = {Yi Liu}, author = {Hu Yang}, author = {Yan He}, author = {Jiang Zhu}, keywords = {directional coupler;double-layer substrate integrated waveguide;comparator network;X-band;frequency 9.5 GHz to 10.5 GHz;magic tee interconnection;miniaturised compact monopulse antenna systems;common broad side;folded parallel SIW;compact monopulse sum-difference comparator;phase shifter;double-stepped coupling slot;}, ISSN = {0013-5194}, language = {English}, abstract = {A monopulse sum-difference comparator based on double-layer substrate integrated waveguide (SIW) for X-band applications is investigated and experimentally validated. A 90° 3-dB directional coupler with a double-stepped coupling slot in the common broad side between a pair of folded parallel SIWs and an equal-length unequal-width 90° phase shifter are adopted to form a magic tee. The four magic tees are elegantly interconnected to design a highly compact comparator. Experimental results show the bandwidth (reflection coefficient < −10 dB) of the comparator can achieve 10% with an operating frequency range of 9.5–10.5 GHz, in which the output amplitude and phase imbalance are within 0.75 dB and 14° (RMS), respectively. The insertion losses are about 1.5–2.5 dB and the isolations between the three channels are all better than 20 dB. In particular, the double-layer configuration of the comparator network reduces the occupied area with the potential for high integration and makes it to be a good candidate for miniaturised and compact monopulse antenna systems.}, title = {Compact monopulse sum-difference comparator based on double-layer substrateintegrated waveguide}, journal = {Electronics Letters}, issue = {22}, volume = {53}, year = {2017}, month = {October}, pages = {1477-1479(2)}, publisher ={Institution of Engineering and Technology}, copyright = {© The Institution of Engineering and Technology}, url = {https://digital-library.theiet.org/;jsessionid=3lolu33spj1w.x-iet-live-01content/journals/10.1049/el.2017.2647} }