Efficient wideband filter using closed loop resonator with coupling lines

This paper is about a wideband filter using closed loop resonator with inter-digital coupling lines. The square resonator is used as closed loop structure integrated with inter-digital coupling on both sides which plays a major key role in this filter design. The proposed wideband filter can be employed in ultra-wideband (UWB) receivers since the operating band of UWB is matching with operating bandwidth of this filter. Design and EM simulation of the UWB filter's characteristics are discussed in this work. The proposed UWB filter produces tremendous bandwidth ranges from 2.3 GHz to 8 GHz. The filter evaluation parameters like return loss, insertion loss, phase and group delay are obtained, and their responses are analysed. The complete size measurement of the filter is achieved to be 39 mm × 3.2 mm × 1.6 mm on accounting the above features. The calculated bandwidth ratio with respect to centre frequency of the filter is obtained about 115%. The performance parameter results show the filter's return loss (S11) and insertion loss (S21) are −41 dB and −2 dB respectively. Both simulation and measured values the UWB-BPF are compared.