Compact wideband band-pass filter using regular hexagon ring resonator

A compact wide-band microstrip band-pass filter with sharp-rejection is proposed and discussed in this paper. This band-pass filter includes a regular hexagon ring resonator and two tuning stubs. Because the regular hexagon ring resonator and two tuning stubs are used, this filter not only features good band-pass filtering property, but also has two sharp stop-bands. In order to verify this new band-pass filter circuit structure and its corresponding design theory, a proposed band-pass filter using common microstrip technology are designed, simulated and measured. The measured results show excellent agreement with the simulated results. The proposed band-pass filter has compact size, low insertion loss, sharp-rejection and simple structure. Furthermore, the measured results of the fabricated microstrip band-pass filter show that the return loss is below 15 dB in the pass-band and less than 1 dB in the stop-band.