A wideband filter-integrated coupler using substrate integrated suspended line (SISL) technology with patterned substrate

A wideband coupled-line coupler based on substrate integrated suspended line (SISL) technology was proposed. The coupler has a conventional coupled line, two variant two-line coupled lines, and four three-line coupled lines, with filtering-integrated function and inherent DC block. By introducing two air cavities and removing certain parts of the substrate, a patterned SISL structure was utilized, with the advantages of self-packaged, low loss, and simple production and processing. The designed coupler has a power-division ratio of 7 dB, and a wide frequency band from 1.21 GHz to 2.11 GHz (54.21%) with S₁₁ <; -15 dB, centered at 1.66 GHz.