Compact UWB BPF using slotted resonator with an independently controllable notched band

Abstract

In this paper, a novel compact ultra-wideband (UWB) bandpass filter (BPF) without and with one sharply notched band is presented. The UWB bandpass characteristic is achieved using slotted resonators (SR) and a notch is obtained by spiral defected ground structure (SDGS) without any change in SR structure. Center frequency of the notched band can be easily changed (from 5 to 9 GHz) by tuning the dimensions of SDGS. To verify the feasibility of the proposed filter, two UWB BPFs, one without the notched band and the other with a notched band, at 8.0 GHz are developed and fabricated, there by suppressing the spurious satellite-communication signal within passband. Measured results of two fabricated filters have the advantages of wide −3 dB bandwidth from 3.1 to 10.6 GHz (which satisfies the requirements of US Federal Communication Commission -specified UWB limits), compact size, low insertion loss (<0.6 dB), and a wide upper stopband with high attenuation (−20 to −50 dB).