Bandpass-to-all-pass reconfigurable filter with wide frequency tuning range

In this work, we propose and demonstrate a bandpass-to-all-pass reconfigurable filter with a wide frequency tuning range. The proposed filter employs frequency-tunable substrate integrated resonators and transmission line with two single-pole double-throw (SPDT) switches. The frequency-tunable second-order reconfigurable filter is designed to support the presented design theory and both operating modes are well obtained.