High Selectivity Dual-Band Bandpass Filter for 5G Mobile Communications

A high selectivity dual-band bandpass filter working at sub-6 GHz spectrum for 5G mobile communications is designed. It consists of two folded open-loop stepped-impedance resonators with four transmission zeros. To further improve the selectivity of the filter, a spur-line is employed to generate another transmission zero (TZ) between the two passbands. The proposed dual-band bandpass filter is operated at 3.61 GHz and 5.54 GHz, its working bands are 3372-3883 MHz and 5072-5889 MHz. The filter has a low insertion loss, compact size, high band-to-band isolation and high selectivity performance.