Research On Microwave Multiplexer And Its Reconfigurability

With the rapid development of modern wireless communication and the higher requirem ents of communication quality,miniaturization,high performance and low cost microwav e multiplexers have attracted more and more attention from researchers.Microwave m ultiplexer connects multiple filters by some coupling mode,so it needs to maintain a high isolation between the filters of each channel,so that it has a good performance of a single microwave filter.The requirement of dynamic range of communication syst em makes the research of multiplexer reconfiguration indispensable.The mean contents and results of this paper are shown below:The first part is the research of star-junction feeding structure diplexer based on stepped impedance resonator.According to coupled resonator filter theory,a bandpass filter based on stepped impedance resonator is designed,and then a star-junction feeding structure diplexer is constructed by connecting the designed filter with a capacitive loading impedance matching network.The CFs,3 d B FBWs,insertion losses(ILs)and in-band RLs of two channels are0.9/1.6GHz,8.3%/9.7%,1.41/1.12 d B,15.1/21.1d B.The isolation is greater than 38.3d B between two channels.In the proposed diplexer structure,PIN diodes are loaded,then a switchable diplexer is designed.By changing the bias voltage of the switching diode,the working state of the diplexer can be switched.There are four working states of the switchable diplexer.When the lower channel is on,its CF,3 d B FBW,insertion losses(IL)and in-band RL are 0.91 GHz,8.7%,1.84 d B and 18.2d B,respectively.When the upper channel is on,its CF,3 d B FBW,insertion loss(ILs)and in-band RLs are 1.6GHz,8.8%,1.49 d B and 19.9d B,respectively.The isolation is greater than 34.3d B between two channels.The second part is the research of triplexer based on modified manifold.A triplexer with modified manifold is presented in this part firstly,which exhibits compact size,low insertion loss,and wide passband.The measured CFs,3 d B FBWs,insertion losses(ILs)and in-band RLs of three channels are 1.21 / 1.8 / 2.41 GHz,14.4% / 14% / 13.6%,1.39 / 1.35 / 1.27 d B,and 11.6 / 14 / 10 d B,respectively.Then,the series-parallel configuration p-i-n diode switches are introduced in the above modified manifold,and a new switchable impedance matching circuit is proposed to design a switchable triplexer.The designed switchable triplexer has eight available operation states,so that it realizes multiple functional blocks in a single module.When three channels are on,their CFs,3 d B FBWs,insertion losses(ILs)and in-band RLs are 1.2 /1.8 / 2.4 GHz,2.2 / 2.7 / 2.4 d B,12.7 / 11.8 / 17.3d B,respectively.The isolation is greater than31 d B between either channels.The third part is the research on tunable diplexer based on common lumped-element dualresonance resonator(LE-DRR).The third-order tunable diplexer with two independently tuned channels consists of one common varactor-tuned lumped-element dual-resonance resonator and two varactor-tuned LC resonators.By changing the control voltage of the varactor diode,realizing the tuning of central frequency of two channels.The 3d B cutoff frequency of its lower channel can be tuned from 0.5 GHz to 1.02 GHz,while the 3d B cutoff frequency of its upper channel can be tuned from 1.01 GHz to 1.78 GHz.