Arbitrary Power-Division Branch-Line Hybrids for High-Performance, Wideband, and Selective Harmonic Suppressions From 2f0

A branch-line hybrid (BH) topology is suggested, consisting of four equal lengths of transmission-line sections (TLs) with two different characteristic impedances and four identical L-sections with each a TL and an open stub. The topology can provide three distinct properties; lower characteristic impedances of TLs, longer electrical paths for the scattering parameters, and additional transmission zeros, enabling high performance of harmonic suppressions from 2f(0), where f(0) is a design frequency, wideband and selective harmonic suppressions. A compact equivalent circuit of a TL is suggested for harmonic suppression BH which can be applied for all possible power-division ratios. As a proof-of-concept demonstration, two prototypes for the power-division ratios of(0) and 6 dB are tested and measured. The measured frequency responses are in a good agreement with the predicted ones, given fabrication errors.