Design of dual-band bandpass filter using compact spiral-shaped microstrip resonators

In this paper, a compact dual-band bandpass filter using spiral-shaped half-wavelength resonator has been designed and implemented. In addition, for transmission zero generation, the tapped-line input/output feed mechanism is used in this filter. Based on this architecture, we can easily achieve a significant size reduction compared with conventional open-loop resonator BPF. A well agreement between measurement and simulation results has been obtained. The designed filter is attractive and suitable for applications where the filter area is very limited.