8 Way Ka Band Radial Waveguide Power Dividers/combiners Design

In recent years, with the development of the millimeter wave technology in wireless communication, millimeter wave communication has been applied in the fields of radar, satellite communications, electronic warfare and so on. To obtain higher information transmission rates over larger distances, it is a requirement of using higher frequency bands and larger transmitted power. However, as the frequency increasing in millimeter wave, the output power of the single MMIC is restricted, which cannot meet the requirement of high power applications. To obtain high power level, the power combination of multiple devices is studied. Thus, it is interesting to develop different kinds of power dividers/combiners.In the design of the millimeter wave power dividers/combiners, because of the high loss of millimeter wave, the way of waveguide-based spatial power combining technique is usually used. Besides, the balance of amplitude and phase is also required in the power combining technique. This thesis focuses on Ka-band radial waveguide-based spatial power dividers/combiners. The characteristics of radial waveguide structures are also studied. The corresponding major frame work is listed as follows:Firstly, the basic theory and research background of power combining technique are discussed in this paper. The effect on combining efficiency is taken by amplitude-phase imbalances, combining network loss and combining stages, which are studied in several techniques of microwave-millimeter wave power combining respectively. In particular, the conditions of obtaining the maximum efficiency of the waveguide-based spatial power combing are analyzed. The electromagnetic problem of radial waveguide is theoretically analyzed.Secondly, one of wideband Ka-band radial waveguide power dividers/combiners is designed. The 8-way broadband radial waveguide power combiner is realized through using magnetic coupling coaxial probe. The advantages of radial waveguide structures are reflected, and the efficiency of power combing is above 95%. In additions, the broad working bandwidth is achieved by using waveguide transforming. Finally, the sample is manufactured fabricated and tested.Thirdly, the other kind of Ka waveguide power dividers/combiners is designed by using a stepped radial waveguide. The coupled mode of the impedance transformation is realized by using a stepped radial waveguide, and the conversion structure of the rectangular waveguide-coaxial-radial waveguide is used. A high efficiency of above 97% is achieved in the working bandwidth. The structural advantages of radial waveguide come to the fore. And the spatial structure has the simple and compact configuration. Finally, the sample is also manufactured and tested.