A Miniaturized (UWB) Bandpass Filter Using Elliptical-Ring Multi-Mode Stub-loaded Resonator (MM-SLR)

Abstract

In this paper, a novel miniaturized ultra-wide¬band (UWB) band pass filter (BPF) with sharp slopes tran-sition band is reported. The UWB BPF (7.45 GHz to 19.85 GHz) consists of modified elliptical-ring and multi-mode stub-loaded resonator (MM-SLR) and symmetry tight coupled resonator (STCR) via input/output (I/O) lines, achieving UWB band pass response. With adding a T-shaped to the middle resonator, two transmission ze¬roes are created at 6.84/23.05 GHz. The proposed filter has the ability of creating a notch band in pass band by reducing the length of two coupled lines that can be con¬trolled based on analytical method. Moreover, the equiva¬lent circuit and the analytical theories of each circuit ele¬ment are proposed. Measured results of fabricated filter have the advantages such as ultra-wide pass band of the defined UWB pass band are 7.45 GHz and 19.85 GHz, satisfying the requirements of FCC-specified UWB limits, compact size, low insertion loss < 0.6 dB and the stop band of the proposed filter is from 19.85 to 33 GHz with attenu-ation of –17 to –29 dB respectively. The proposed UWB filter is realized using the substrate with dielectric constant of 2.2 and substrate height of 0.787 mm Experimental veri¬fication is provided and good agreement has been found between simulation and measurement.