Frequency-asymmetrical signal-interference microwave planar filters based on stub-loaded transversal filtering sections

A new family of signal-interference planar bandpass filters (BPFs) with frequency-asymmetrical transfer function is reported. They are made up of modified transversal filtering sections (TFS) having short-circuit-ended stubs in their signal-propagation paths. Through this technique, by synthesizing the load stubs as in-band resonating nodes in both single- and multi-band BPF realizations, higher selectivity when compared to that of their conventional counterparts is achievable. Furthermore, as experimental verification, a dual-band BPF prototype in microstrip technology with strongly-asymmetrical passbands for the double band 0.56/1.28 GHz has been built and measured.