超宽带大功率合成器设计

Design of a Ultra-wideband High Power Synthesizer

在80 MHz~1 GHz频段,单个功率管输出功率能达到100 W以上,为研制输出功率400 W的功率放大器,文中设计了四路功率合成器。该合成器需要实现功率容量大、工作频带宽、体积小的设计目标。在功率容量方面,文中采用悬置带状线结构,其功率容量远远大于微带线结构;在工作频带方面,采用切比雪夫九节阻抗变换器,将工作带宽拓宽为80 MHz~1 GHz;在体积方面,文中合成器的功率合成部分采用Y型节级联实现四路功率合成,阻抗变换部分采用切比雪夫阻抗变换器进行阻抗变换,该结构相较于磁环巴伦功率合成器,不但具有损耗小、平坦度高的优点,而且通过将阻抗变换器设计成曲折的形状,进一步缩小了合成器体积。仿真与实测结果显示该合成器在80 MHz~1 GHz范围内还具有较高的平坦度,合成效率可达90%以上。

In the frequency band of 80 MHz-1 GHz, the output power of a single transistor can reach more than 100 W. In order to realize a power amplifier with an output power of 400 W, this paper designs four-way combiner. The combiner needs to achieve the design goals of large power capacity, wide operating frequency and small size. In terms of power capacity, the air suspended strip line structure is adopted in this paper, and its power capacity is far greater than that of microstrip line structure. In the aspect of working frequency band, Chebyshev nine-section impedance converter is adopted in this paper, which broadens the working bandwidth to 80 MHz-1 GHz. In terms of volume, the power combine adopts Y-shaped section cascade to realize four-way power combination, and the impedance transformation part adopts Chebyshev impedance transformer to carry out impedance transformation. Compared with the magnetic Balun, this structure not only has the advantages of low loss and high flatness, but also further reduces the volume of the combiner by designing the impedance transformer into a zigzag shape. The simulation results show that the combiner has high flatness in the range of 80 MHz-1 GHz, and the combination efficiency can reach over 90%.