High-Selectivity Performance Dual-Mode Folded Half-Wavelength Resonator Band Pass Filter for 5G Networks

This paper presents the new dual-mode half-wavelength folded microstrip resonator. The capacitance effect achieves the external coupling by changing the gap distance, while stub loading achieves the internal coupling. The second-order Chebyshev bandpass (BPF) filter was simulated by HFSS software on a thin Rogers substrate. The BPF is operated at a center frequency of 1.980 GHz, which results in a return loss of 16.97 dB, while the insertion loss is equal to 1.2185 dB. The BPF measures its bandwidth at 3 dB, which is equivalent to 50 MHz. The spurious frequency occurs at 4.27 GHz. The resonator offers a size of about (0.726λg× 0.278λg) which is smaller than a single mode. Moving the feeding line close to the center of the resonator has significantly enhanced the spurious window by about 2.75, and two Tzs appear on both band sides. The results show a satisfactory agreement with the requirement for 5G applications