volume | PIER Journals

Abstract

The performance requirements for filters in the microwave frequency band are particularly stringent, particularly in terms of high bandwidth and out-of-band rejection. However, meeting these requirements within the constraints of a compact size presents a significant challenge. A coupled step-impedance resonator bandpass filter is proposed. The filter combines U-shaped branches and L-shaped branches to create multiple resonance points while expanding the bandwidth, and the in-band ripple is also improved by this folded structure that greatly reduces the filter size. The microstrip filter measures only 9.6 mm × 8.8 mm × 1.1 mm, has a center frequency of 4.65 GHz, and achieves a relative bandwidth of 60.2%. The filter can be used in 5G n77 (3300~4200 MHz), n78 (3300~3800 MHz), n79 (4800~4960 MHz), and WLAN (5150~5850 MHz) bands. In addition, the filter has a left-side rectangular coefficient of 1.12, insertion loss <0.4 dB, and return loss better than 17 dB.

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Dr. Jiajia Wang

Dr. Shuo Yu

Dr. Xiaofan Yang

Prof. Xiaoming Liu