Design of Balanced Filtering Components Based on Transmission Line, Substrate Integrated Waveguide and Patch Resonators

A mini-review of our research on the design approaches of balanced filtering components is presented in this paper. According to the wave propagation and resonant modes, three design methods based on our published works are summarized. The first one is the utilization of resonances along the transmission lines. Four representative multi-functional filtering circuits with balanced or balanced-to-unbalanced performance are displayed for demonstration. The second way is to use the TE102-mode in the substrate integrated waveguide (SIW) cavity, which is demonstrated by a design of Ku-band balanced bandpass filter (BPF). For the third one, it is introduced with the exploitation of resonant modes in triangular and square patches, including designs of balanced BPF and filtering power divider.