Author:
Firmli Maroua,Zatni Abdelkarim
Abstract
Since several decades ago, parallel coupled lines have found an extensive range of applications in order to design microwave circuits such us filter, impedance transformers and couplers. It gives advantages in term of low cost, easier integration with other devices and controllable performances by changing coupling coefficient between lines. This paper presents a review of parallel two and three interdigital coupled lines bandpass filters for ultra-Wideband (UWB) communication systems during previous years to achieve a fraction passband from 3.1 GHz to 10.6 GHz and then a FBW that can reach 109%. Different structures such as multiple-mode resonator, Short Circuited Stubs, Open stub, Stepped-impedance resonators and Rectangular Ring have been reportedly used to ameliorate the performances of developed filters.