dual-band microstrip bandpass filter for wireless applications

This study presents the design, simulation, and validation of a compact dual-band microstrip bandpass filter developed for wireless applications, operating within the 2.47–2.68 GHz and 5.02–5.45 GHz frequency ranges having operating frequencies at 2.6 GHz and 5.07 GHz. The filter utilizes edge-coupled square ring resonators along with split-ring structures to achieve improved frequency selectivity, low insertion loss, and reduced mutual interference between the bands. A 4th-order Chebyshev low-pass prototype with a 0.5 dB ripple serves as the basis for the design. Ansys HFSS (High Frequency Structure Simulator) is used to perform detailed electromagnetic simulations, helping to optimize physical parameters such as resonator lengths, coupling gaps, and feedline placements. This ensured the filter worked well at both frequency bands. The filter is fabricated on an Epoxy FR4 substrate with a dielectric constant of 4.4 and a thickness of 1 mm, the filter offers a cost-effective and compact solution while maintaining good return loss. Experimental validation using a Vector network analyzer showed close alignment with simulated results, confirming the accuracy and practical viability of the design.