Dual-Band Microstrip Filter Using a Multilayer Structure for Wireless Applications at 2.45 and 5.8 GHz

In this paper, a new miniaturized configuration of single-input-single-output (SISO) dual-band bandpass filter operating at ISM 2.45 GHz and UNII 5.8 GHz frequency bands using a multilayer structure this stepped-impedance resonators is presented. A coupling aperture is introduced in a common ground to ensure the coupling between the two resonators located in the upper layer and the lower one. The use of stepped-impedance resonators allows tuning the two bands at desired frequencies. Finally, a design example was fabricated to validate the proposed concept. The insertion loss and return loss at the central frequency are -1.35 dB and -17 dB for 2.45 GHz band, respectively, and, -0.98 dB and -13 dB for the 5.8 GHz band, respectively. There is a good agreement between experimental and full-wave electromagnetic (EM) simulation results.