Electromagnetic Design and Actual Fabrication of a Bandpass Cross-coupled Filter Applied for Mobile Communication

This paper outlines the design and development of a cross-coupled bandpass filter with operational frequency at 1.2 GHz, intended for mobile communication applications. To enhance computational efficiency, the filter is decomposed into individual components and each part is simulated separately using HFSS simulator and AWR software, which facilitates the extraction of critical parameters in accordance with a general coupling matrix (CM). A Rogers RO4003C substrate with a thickness of 0.813 mm and dielectric properties of εr = 2.2 and tanϕ = 0.0027 was used in the simulation. The dimensions of the fabricated cross-coupled filter are as follows 25 × 52 × 0.847 mm3, where the filter shows a desirable frequency response with two transmission-limiting zeros as expected. The simulated cross-coupled filter has an excellent electromagnetic performance, it exhibits an insertion loss of 1.1 dB and a return loss of –25 dB within a frequency range of 1.13 GHz to 1.28 GHz. The results show that the analysis, simulation and measurements agree well with each other, proving the accuracy and efficiency of the filter design.