Research On Microwave Electrical Tunable Planar Passive Component

Passive component is one of the most significant parts in the communication system. Its performance directly influences the communication’s quality. Electrical tunable passive component has the advantage of compactness and low cost, so it can cater to the requirement of the modern communication system. This paper utilizing varactor diodes, presents several electrical tunable passive components. The main works are as follows:1. Four electrical tunable filters have been presented. First, a broadband electrical tuning bandpass filter with constant fractional bandwidth using H shape resonator is designed. By introducing the high impedance line between the resonators, the coupling can be compensated and the broadband tuning response can be realized. Then an electrical tunable bandpass filter with constant absolute bandwidth is proposed using compensating structure. Due to the simple structure, the circuit has the advantage of low insertion loss. The measured insertion loss is less than 3 dB. After that, a switchable bandpass/bandstop filter with tunable working frequency is designed. Using switch property of the PIN diodes, the filter’s response can be changed from bandpass to bandstop. By tuning the varactor diodes’ biasing voltages, the working frequency can be altered. Last but not least, an electrical tunable balanced filter with absolute bandwidth using interdigital structure is presented. Because the interdigital structure can make up for the coupling between the resonators at different frequency, the tunablity can be realized. The measured results verify the design methods.2. An electrical tunable Wilkinson power divider and an electrical tunable diplexer are designed. The electrical tunable Wilkinson power divider is employed loaded varactor diodes in the Wilkinson power divider which makes the power divider’s working frequency tunable. The electrical tunable diplexer is based on the design of a tunable filter. Due to the symmetrical structure, the output ports’ working frequencies can be exchanged. Measured results verify the design methods.