Parallel coupled microstrip bandpass filter for short range UWB applications

Abstract

Bandpass filter is presented based on parallel coupled line microstrip structure suitable for short range Ultra-Wideband (UWB) applications. Chebyshev filter of order 4 and 0.2 dB passband ripple with fractional bandwidth of 86 % is designed using insertion loss method. The proposed filter demonstrates -10 dB bandwidth over the range 3.9 GHz to 9.8 GHz and has linear phase response in the operating band. The analysis of the filter is performed by using MoM based electromagnetic solver, IE3D. With the above functional features the overall dimension of the filter is 31 mm (height) × 4 mm (length) × 1.6 mm (breadth). It is not only compact but also delivers excellent scattering parameters with the magnitude of insertion loss, |S 21| lower than -0.5 dB at center frequency, 6.85 GHz and return loss better than -32.67 dB. In the passband, the computed group delay is well within the tolerable variation of 0.02 ns. © 2011 Springer-Verlag.