Miniaturization Of Comb Filter Technology Research

With the development of wireless communication, satellite communication, radar and missile guidance, the design specifications of filter have become more and more important for microwave communication system. The microwave filter with small volume, high-performance and low cost makes a difference for the next generation of wireless satellite communication technology. According to this target, in the base of the basic theory and capacitance loading technology, this paper will show you a series of comb filters with high-performance and small volume. The main jobs of this paper are as follows:First of all, the history and current status of the miniaturization technology for microwave filter will be described. It will also give a summary analysis for microwave filter, especially the equivalent circuit and deriving formula of comb filter.Secondly, according to the existing theory for microwave filter and the electromagnetic simulation software, how to determine the original size of microwave filter’s resonant cavity and coupled structure will be described. Then, this paper will present a design method which changes the value of the group delay of S11. This method can design cavity and waveguide bandpass filter quickly and effectively. Based on this method, uniform and T-type comb filter can both be designed. Comparing with uniform type, T-type involves more loaded capacitance, which decreases filter’s volume to a large extent. So T-type realizes the miniaturization design for comb filter.Finally, it will show you how to determine the original size of tapped input and output coupling structure with the help of changing the value of the group delay. With the method above, a kind of ultra-narrow-band comb filter can be designed. A kind of compact surface-mount filter will also be given. Due to its small volume, low insertion loss, high power and easy to be integrated, it may take the place of microwave filter in the millimeter wave integrated circuits, such as satellite communication and missile guidance system.