A Compact UWB Bandpass Filter with WLAN Band Rejection Using Hybrid Technique

Abstract A compact Ultra-wideband (UWB) band-pass filter (BPF) based on a hybrid technique using a CPW-Microstrip-CPW transition is designed with WLAN band rejection. The proposed bandpass filter is mounted on a Rogers RO4350 substrate with a thickness of 0.508 mm. The presented UWB bandpass filter has good bandpass quality with 20 dB return-loss bandwidth from 2.9 to 12.2 GHz and insertion loss better than 0.5 dB with group delay UWB BPF about 0.22 ns. We can note that this latter is flat in the entire bandpass which indicates that the filter is efficient. . In addition, by implementing the closed-ring resonators (CRRs) on the bottom plane, we observe an appearance of the notched band. The center and bandwidth of the notched band can be controllable by adjusting the length and width of the CRRs. Thus, the presented filter can be beneficial for low profile future wireless communication systems. Simulation of this proposed filter is carried out on CST MWS software.