A Self-packaged SISL 3-dB Lange Coupler Suitable for PCB Fabrication

A 3-dB Lange coupler using substrate integrated suspended line (SISL) technology is proposed in this paper. As compared to the conventional Lange couplers, the proposed self-packaged SISL Lange coupler increases the coupled-line width and spacing, and avoids using bonding wires. The SISL air cavity structure with via-holes surrounded is introduced to reduce the radiation loss. The suspended substrate is partially cut out in pattern to further reduce the dielectric loss. The measured results agree well with the simulated ones. In the working frequency band from 2 GHz to 3 GHz, the measured return loss and isolation are both better than 17.8 dB. The measured phase difference between the direct and coupled ports is 91±1°.