Design of a broadband frequency-tunable planar filtering power divider

ABSTRACT In order to meet the development requirements of multi-frequency and functional integration of radio frequency (RF) modules, a broadband tunable filtering power divider with center frequency is designed. A new structure is composed of open branch line, step impedance resonator, and double branch resonator. The filter response is realized by branch line and double branch resonator. The resonant frequency of the device can be adjusted flexibly by controlling the varactor diode loaded on the two resonators with external voltage. The double branch resonator can realize the broadband frequency adjustability, the step impedance resonator can improve part of the return loss performance of the device, so that the central frequency can achieve high performance in a wide tuning range. The research results show that the center frequency of the designed filtering power divider is adjustable in the range of 1.6 GHz to 2.7 GHz, the tuning bandwidth is 51.2%, the input return loss of each center point is better than 20 dB, and the isolation between output ports is better than 19 dB. The device is expected to be widely used in RF communication systems such as array antennas and transceiver components.