Design of a Ultra-wideband High Power Synthesizer

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%.