Dual-band filter using multilayer structures and embedded resonators

A new miniaturised configuration of a single-input-single-output dual-band bandpass filter operating at 2.45 and 5.8GHz frequency bands is presented. The proposed filter is composed of four sub-miniaturised open-loop resonators (OLRs) embedded into two main basic stepped-impedance resonators (SIRs) used as the principal part of this filter. The use of SIR and OLR resonators allows controlling the lower and upper bands, respectively, to achieve the required frequency bands. Finally, a design example was fabricated and measured.