A Low-Loss Self-Packaged Magic-T With Compact Size Using SISL Technology

This letter proposes a low-loss self-packaged magic-T with compact size using substrate integrated suspended line (SISL) technology. The microstrip-slot transition is embedded inside the SISL multilayer structure and thus the radiation loss caused by the slot can be reduced to minimum. The measured results, which agree well with the simulation ones, show that from 5 to 9 GHz, i.e., 57% fractional bandwidth, the measured return loss of each port is better than about 10 dB, the measured isolation between difference port and sum port is better than 35 dB, and the measured amplitude imbalance and phase imbalance are ±0.8° and ±0.14 dB, respectively. The implemented magic-T has a compact size of 0.18λ
_g
× 0.43λ
_g
, which is much smaller than previous designs.