Compact Band Notched UWB Filter for Wireless Communication Applications

The paper presents an ultra wide band filter using asymmetrical interdigital coupled line with a transmission notch at the WLAN band. The lower side transmission zero can be conveniently tuned by stepped impedance resonators of proper dimensions. The frequency notch for WLAN band is introduced by two half wavelength open ring resonators etched on the ground plane. The attenuation in lower and upper stopbands is controlled by the use of series capacitors and Defected Ground Structures respectively. The insertion loss in the passband is improved by circular apertures in the ground plane. Measured frequency response of the fabricated filter shows good agreement with simulated results.