Miniaturized (UWB) Band Pass Filter Using Elliptical-Ring Multi-Mode Stub-Loaded Resonator (MM- SLR)

In this paper, a novel miniaturized ultra-wideband (UWB) band pass filter (BPF) with sharp slopes transition band is reported. The UWB BPF (7.45 GHz to 19.85 GHz) consists of modified elliptical-ring and multimode 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 zeroes 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 controlled based on analytical method. Moreover, the equivalent circuit and the analytical theories of each circuit element 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 attenuation 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 verification is provided and good agreement has been found between simulation and measurement.