Ka-band Spatial Power Combining Amplifier Developed

Millimeter-wave power amplifiers are crucial in the design of transmitters at millimeter-wave frequencies. The approach of power combing is an effective solution for greater output power, when output power restricted by the output of single device. New technology of power combining is the key of millimeter-wave solid-state power transmitting when the old ways meet some difficulties.At present, the circuit combination structure and spatial combination structure are most adopted. For radar transmitters at millimeter-wave frequencies, circuit combination structure isn't suit. Because the electrocircuit loss and circuit area increased nonlinear when accessory increased. Therefore, the number of accessories that circuit combination structure can combine is limited. The advantage of spatial combination structure is that combining efficiency is foreign to number of accessories. Based on this advantage, spatial combination structure is fit for high power output because it can use more accessories. So that spatial combination structure is used to make high power amplifier.This paper has analyzed the power splitter network mostly used in mm-wave frequency band in detail, on the general analytic basis of the development of overseas mm-wave spatial power combination and amplification technology. Some spatial power combination structures are analyzed, simulated and optimized respective. Compared the simulation result of these structures, the best one is T-junction unit improved waveguide-microstrip double probes power combination structure. This structure is different from the slotted-waveguide power combining and wave-guide-based power combining. Besides innovation, this structure has found how to placed many accessories in finity room and improved the phase difference and amplitude difference in combination structure.Based on the researching and experimenting, the high-power amplifier that can provide output power more than 9w in the 30.5-37.5GHz has been completed. Between 30.5-37.5GHz, the small signal gain is more than 49dB. The amplifier can provide a maximum output power of 13.8W at 31 GHz. The measured minimum saturation output power is 39.7dBm and the maximum saturation output power is 41.1dBm in the 33～36GHz working band, and the average combination efficiency is 81.3%.