A 0.94 ∼ 1.50 GHz Constant Absolute Bandwidth Tunable Bandpass Filter with Electric Coupling

摘要

In this paper, a method to get the electrically tunable bandpass filter with constant absolute bandwidth base on electric coupling is presented. By changing the position of the capacitor, the resonator can conveniently obtain the different slopes coupling line, and the constant bandwidth filter can obtain. Varactors are used as the tunable elements. The prototype with overall size of 60 mm ×52.4mm×0.8 mm was simulated so as to validate the new structure. The simulated central frequency is 0.94 GHz and 1.50 GHz, the insertion loss is 2.0 dB and 2.2 dB, and the absolute bandwidth is 130±5 MHz, at the biasing voltage of 0 V (27.6 pF) and 25 V (1.8 pF) respectively.