Parallel-coupled Microstrip Bandpass Filter Research Articles

Behaviour of Parallel Coupled Microstrip Band Pass Filter and Simple Microstripline due to Thin-Film Al2O3Overlay

The X-band behaviour of a seven-section parallel-coupled microstrip band pass filter and microstripline due to thin-film Al2O3overlay of different thickness is reported in this paper. This Al2O3film can give a homogeneous overlay structure. There is a substantial increase in the bandwidth due to the overlay, the pass band extending towards higher frequency side. In most of the cases, an increase in the pass band transmittance of a microstripline also increases due to a thin-film Al2O3overlay, especially for frequencies less than 9.0 GHz. At higher frequencies, random variations are observed. It is felt that thin-film overlays can be used to modify the microstripline circuit properties, thereby avoiding costly and time consuming elaborate design procedures.

Design of parallel coupled microstrip band-pass filters

A simplified method of the design of a parallel coupled microstrip band-pass filter is outlined. A set of curves is presented for getting the geometry for filters with band widths less than 10%. A filter is designed and tested for illustration.