<i>Ku</i>-Band Self-Packaged Balanced Magic-T and Filtering Power Divider Based on Substrate-Integrated Suspended Sandwich Slotline With High Isolation

On the substrate-integrated suspended line (SISL) platform, a broadband balanced magic-T and a filtering power divider (FPD) based on the sandwich slotline to a grounded coplanar waveguide (GCPW) transition structure are proposed. These devices achieve high isolation and common-mode (CM) suppression, and their self-packaged design offers excellent anti-interference capabilities. First, the magic-T is designed by connecting a cross-junction and differential feeding ports, achieving balanced-to-single-ended (BTSE) power division with out-of-phase and single-ended-to-single-ended (SETSE) power division with in-phase. This device is then self-packaged, resulting in low insertion loss in the Ku-band. Next, a tri-mode sandwich slotline resonator filter unit is inserted into the path of port E of the mixed-mode magic-T, and a matching load is connected to port H, ultimately realizing a BTSE FPD with filtering characteristics. Through characteristic mode analysis, it is revealed that the novel resonator generates three modes. For experimental verification, the aforementioned broadband BTSE-SETSE magic-T and BTSE FPD are fabricated and measured. Both devices demonstrated high CM suppression and isolation, as well as stable amplitude–phase consistency. In addition, a pair of transmission zeros is introduced on both sides of the passband of FPD, significantly enhancing selectivity.