Ka-band Power Distribution Synthesis, Network Design,

Power amplifier is an important part of Millimeter wave communication system,its output power determined the working radus of system.In the ka-band, the traditional power amplifier using electric vacuum devices, the transmit power is high but larger in volume, poor stability , and the maintenance is complex and costly. In recent years, with the development of millimeter-wave MMIC chip, millimeter-wave solid-state power combining technology has become a research hot spot. Power combining technology is to combine the output power of several MMIC chips through a power divide/combine network in order to achieve high power output. Compare with the traditional electric vacuum devices, it has a higher stability, smaller size, longer life and easy of maintenance. Commonly used power divide/combine structure are binary-type waveguide power combing structures,such as T-junction, waveguide directional coupler.Such structures are popular in engineering, the design is simple, and easy-to-modular, but hard to achieve wide bandwidth when multi-channel combine, plus, volume and the loss increased exponentially which affect the combine efficiency. In contrast, chain style combining technology has a high combine efficiency and easy to heat, but due to the design process is complex and require high machining precision, the corresponding theoretical and experimental research is few.This article describes the basic theory of power combing technology, focusing on analysis of commonly used waveguide T-junction, waveguide directional coupler, as well as the waveguide microstrip transition technology. According these theory ,the author designed and fabracated a ka-band T-junction, waveguide directional coupler and waveguide-microstrip transition.Based on the principles of chain-style power combing,this paper proposed a novel structure of the eight way waveguide power divider / combiner structure. The structure is based on traveling wave-type waveguide power divider principle, by changing the size of waveguide to achieve different coupling coefficient in order to achieve equal power divide.It has a broadband, high combing efficiency characteristics. From the simulation results, the 26.5GHz-35GHz range, gain and phase were in good agreement, back to back an average insertion loss is less than 0.5dB, and combining efficiency is above 92%. Test results show the average insertion loss is 3dB in the 29GHz-36.5GHz range, combining efficiency is 70.8%, and simulation results have a slight bias. Test results and simulation results have a slight bias.