Novel UWB BPF with a controllable notched band using hybrid structure

In this letter, an ultra-wideband (UWB) bandpass filter (BPF) based on CPW-to-microstrip transition structure is proposed. To improve its selectivity, an interdigital coupled-line and split ring resonator (SRR) are used to generate two extra transmission zeros located at the lower and upper edge of the passband separately. The measured results show that the proposed filter possesses satisfactory performance such as compact size, sharp roll-off, and wide fractional bandwidth of 133% (2.35-11.75 GHz). Moreover, a notched band with deep attenuation introduced by coupling T-shaped short stub (CTSSS) is achieved to block the ITU8.0 band with centre frequency of 8.2 GHz. And the notched band is controllable. This filter can be a good candidate for ultra-wideband applications.