High-performance Millimeter Wave Multiplexer

Multiplexer is an important component for channel selection and signal synthesis and separation in modern microwave and millimeter-wave systems, its electrical performances are crucial for communication systems. Since the resources of frequency become scarcer, the frequency spaces become narrower in kinds of communication systems. The key technical requirements for multiplexer include low-loss, narrow-band, high isolation, compact size, sharp frequency selectivity, low costs and fast design.In this paper, a proper method to design the high performance millimeter-wave multiplexer is researched. Waveguide has the advantage of low insertion loss, which is the preferred structure to achieve the high performance multiplexer. The filters which can generate transmission zeros have sharp frequency selectivity and small rectangular coefficient, their functions are preferred to achieve the high performance multiplexer, while the application of multimode, which could decrease the size and weight of the multiplexers significantly, is preferred to achieve the high performance multiplexer.The main works are as follows:(1). The equivalent circuits of the filter are analyzed, from which the coupling coefficients are optimized.(2). The filter functions are analyzed, especially through derivation of generalized chebyshev filter polynomial, the coupling coefficients are synthesized and reduced.(3). The basic design methods and steps are given through the actual design of the E-plane metal septum waveguide filter, based on which the diplexer is designed.(4). The folded E-plane metal septum waveguide filters based on cross-coupled resonators are designed, which can achieve steeper attenuation slopes.(5). The structure and the basic theory of the dual-mode circular waveguide filters are studied, from which the simulation results are given.(6). The dual-mode rectangular waveguide filter and multiplexer are designed. The result shows that the dual-mode waveguide multiplexer, which can generate transmission zeros, has high performance and will be helpful in engineering application.