Miniaturized Ultra-Wideband Filter And Filtering Hybrid Ring Coupler

With the rapid development of wireless communication systems,microwave passive components play crucial roles in the RF front-end. Inorder to adapt to the requirements for miniaturization and broadbandperformance of the passive devices in the communication systems, a novelminiaturized ultra-wideband (UWB) filter as well as a novel miniaturizedfiltering hybrid ring coupler are designed respectively in this paper. Themain work of this paper can be summarized as follows:Firstly, a compact notched ultra-wideband UWB bandpass filter withimproved out-of-band performance using electromagnetic bandgap (EBG)structure is proposed. Primarily, a UWB bandpass filter based on astepped-impedance stub-loaded resonator (SISLR) is combined withEBG-loaded structures, which suppress the undesired spurious bands toimprove the out-of-band performance. In order to eliminate theinterference caused by WLAN, a notched band is introduced, which isimplemented by adding a folded stepped-impedance resonator (SIR) nearthe stub of the SISLR. At last, the proposed filter is fabricated andmeasured. Good performances of the UWB filter have been demonstratedboth in the simulated and measured results.Secondly, a novel compact UWB filtering hybrid ring coupler withwide upper stopband based on double-sided parallel-strip line (DSPSL) isproposed. First, based on the theory of hybrid ring coupler with ideal phaseinverter and an equivalent UWB filter prototype, an ideal UWB filteringhybrid ring coupler is introduced. As to realization, in order to improve theperformance of the phase inverter within the broadband, DSPSL structurehas been applied. In addition, EBG-loaded structures are also imported into the structure to widen upper stopband and reduce the size of coupler.Finally, based on the simulated and measured results, it has been provedthat the UWB filtering hybrid ring coupler is feasible.