A substrate integrated coaxial line dual-band balun for 5G applications

This paper demonstrates the design of a dual-band substrate integrated coaxial line (SICL) balun operating at 6 GHz and 28 GHz for 5G application. The proposed design is realized using open-ended coaxial stubs with shielding. The performance of the dual-band SICL configuration is analyzed and range of realizable frequency ratios is determined from the analytically derived equations. The designed SICL based balun demonstrates low amplitude and phase imbalance in both the desired bands with good inter-band suppression making it worthy for practical applications. A fractional bandwidth of 17.6% and 3.97% at 6 GHz and 28 GHz band respectively is achieved by the proposed balun covering 0.43?g × 0.68?g circuit area. The electromagnetic robustness and wide-band single mode TEM characteristics of the proposed SICL based dual-band balun makes it a befitting option to deploy in millimeter-wave range.