Dual-band SHF reconfigurable bandpass filter using λ/4 microstrip resonators and chip inductor coupling

For more flexible and efficient use of radio spectrum, reconfigurable RF devices will play an important role in the future wireless systems. In 5G, concurrent operation of multiple RF bands is considered including new SHF bands over wide frequency range. This paper presents an SHF concurrent dual-band bandpass filter (BPF) consisting of a low-SHF three-bit/eight frequencies (3.5-5GHz) reconfigurable BPF and a high-SHF (8.5GHz) BPF. It employs a direct parallel-connected configuration of the two BPFs without divider/combiner. The prototype BPF can switch low-SHF passbands without affecting the high-SHF BPF performance. The low insertion losses from 1.6 to 2.1 dB are achieved for low-SHF frequencies, whereas that for high-SHF BPF is 2.3 dB.