Design of Compact UWB Bandpass Filter with Multiple Notches using Stepped-Impedance MMR and Interdigital Coupled Line

Abstract

The proposed design is a compact ultrawide-band bandpass filter suitable for unlicensed wireless communication applications from 3.1 to 10.6 GHz at center frequency 6.5 GHz with improved lower and upper stopband performance. Central part of the filter is a uniform stepped impedance multimode resonator (SIMMR) consists of three vertical steppedimpedance stubs. The input and output of SIMMR is connected to three interdigital coupled lines which provide UWB characteristics. Multiple notch bands at 5.2 GHz, 7.5 GHz and 8.5 GHz are introduced within the passband of the UWB bandpass filter to avoid the interference with other signals by using a meander lines which are inserted into one of the coupled interdigital line at the input and output of UWB is bandpass filter to obtain notches in the passband. Notch frequency is easily controlled by selecting the no. of meander slots and its height. Filter is designed on the inexpensive substrate FR4 of dielectric constant 4.4 and height 1.5 mm. Ansoft HFSS is used to simulate and optimize the design.

Keywords

• multi-mode resonator
• UWB
• bandpass filter
• interdigital coupling
• meander line