Design and development of half wavelength vialess bandpass microstrip filter

Abstract

This report presents a half-wavelength vialess bandpass microstrip filter derived from a quarter-wavelength short-circuited stubs model. This project is used the Ultra Wideband (UWB) frequency spectrum in order to produce the wide bandwidth. The filter is designed from 4.85 GHz to 8.65 GHz which in the range of UWB frequency spectrum. In this filter design, there are no connecting vias as short-circuit element. Generally, via can contribute to signal loss and degradation of signal quality due to its discontinuities in circuit parameters. Besides, via are radiative and capacitive in its complex parameter and also require additional process like drilling of holes that makes the fabrication process more complicated. To reduce the unwanted parameters, the filter is designed using half wavelength open-circuited stub model to remove vias. Based on the simulated result in schematic, the filter delivers 5.140 GHz to 9.540 GHz frequency range with 61.62% fractional bandwidth. While for layout, the filter delivers 4.974 GHz to 9.264 GHz frequency range with 62.04% fractional bandwidth. Based on the result, the return loss and insertion loss of this project is acceptable and meet the requirement.