The Design Of Rectangle Waveguide Multiplexer

Millimeter wave is between microwave and light wave, and it is of great potential application in radars, science and communications. The research of millimeter wave devices becomes more and more urgent. As an important device of millimeter wave communication system, the multiplexer plays a decisive role to the performance of communication system. Therefore, it is meaningfully significant to discuss the design of the multiplexer.Many problems will appear when a multiplexer is applied in millimeter wave band, such as increasing high-frequency loss and decreasing size, which arise from wavelength-size-matching effect. It is difficult to obtain the same surface finish quality and roughness as that of low frequency. Furthermore, the insertion loss increases significantly as a result of increasing high-frequency loss. Consequently, rectangular waveguide is applied in the multiplexer other than a coaxial that used in low frequency, and the manifold multiplexer is adopted to minimize insertion loss.Microwave communication band becomes more and more crow with the rapid development of satellite communications and mobile communications. Contiguous-band multiplexer is widely used in order to make the most of the limit spectrum resources. The significant interaction of the contiguous-band channels makes the design of manifold multiplexer becomes very difficult. Therefore, the channel filters are designed by the prototype of singly terminated filter to reduce the interaction of the contiguous-band channels.The rapid design process of millimeter-wave waveguide multiplexer and contiguous-band waveguide multiplexer is analyzed. First, singly and doubly terminated filter is selected depend on whether the channel band is contiguous or not. Second, optimization of circuit model is accomplished based on circuit model. Last, pre-bias is applied to 3D model with the consideration of the effects of temperature and mechanical tolerances.The space mapping technique is widely used to optimize multiplexer, since it is fast and accurate. The electromagnetic simulation software μWave Wizard, which is based on space mapping technique, is used for the design of multiplexer.Three multiplexer are designed in this paper. One is a Ka-band multiplexer, another is a V-band diplexer, third is an X-band waveguide contiguous band multiplexer.