Research Of The Tunable Filter Using In The Multicoupler

In modern wireless communication systems, especially in the military wirelesscommunication systems, the communication interference and anti-interference technology isalways a hot research area. To interference the enemy’s communication systems and ensureone’s own communication system at the same time, the initiative of the battlefield will begrasped in our hand. For the features of reliability, all-weather and stability, the ultra-shortwave anti-interference frequency hopping communication is an important research topic in thefield of the anti-interference communications. As an important part of the ultra-short waveanti-interference frequency hopping communication system, the ultra-short waveanti-interference VHF/UHF multi-coupler and its key component, the tunable filter, is alwaysa hot study pot. Closely integrated research project and take the tunable filter using in theVHF/UHF multi-coupler as the goal, this paper carried out a systematic study the design andengineering realize of the tunable filter. The author’s major work and contributions areoutlined as follows:1. The basic theory and design methods of the multi-coupler and the tunable filter usingin the multi-coupler is summary in this paper. In this paper, combining the designconsideration of the multi-coupler and tunable filter together, and starting from therequirements of the multi-coupler, through analyzing the interactions among the multi-couplerand tunable filters, we get some specially specifications that the tunable filter must meet. Thedevelopment of the ultra-short wave anti-interference technology requires that themulti-coupler must have more communication channel, a wider hopping range and a constantbandwidth in the hopping range. The resulting requirements for the tunable filters are asmaller port susceptance, a wider tunable range and a constant bandwidth in the operating.2. The form of the input/output coupling loop of the coaxial-cavity tunable filter and itscorresponding susceptance characteristic in the port was studied in this paper. And this papersummarizes the traditional design method of the input/output coupling loop in thecoaxial-cavity tunable filter and analyzes its limitations starting from the port susceptancecharacteristic. And then a double loops coupling structure is proposed also its workingprinciple analyze. Finally, a coaxial-cavity tunable filter adopting this coupling structure isdesigned and a desired performance is obtained.3. The study of the coupling structure between cavities of the coaxial cavity filter is carried out in this paper and its designed method is summarized. The reasons for bandwidth ofthe coaxial cavity tunable filter becomes wider and wider is analyzed in this paper. And then ainter-cavities coupling structure constitute of coupling window and coupling loop is presentedand realized an almost constant bandwidth coaxial cavity tunable filter in its operating range.4. The study of the auto-tune method using in the coaxial cavity tunable filter is carriedout in this paper. Through analyzing the features of the coaxial cavity tunable filter, anauto-tune method based on the space mapping and parameter extraction is proposed in thispaper. And the space mapping and parameter extraction are improved to meet the demand ofthe coaxial cavity tunable filter. Finally, the method is verified.5. The study of the other type tunable filters is carried out in this paper, mainly aim to thenon-mechanical tune tunable filter. The study is focuses on the tunable filter based on thephase shifter and ferrite. Two tunable filters based on the phase shifter and a dielectric tunablefilter based on ferrite operating in TM mode is introduced in this paper. Finally, the method isverified through simulation.