Ka-band Planar Power Combining Technology Research

Millimeter-wave power amplifier is a key component in most systems at millimeter-wave frequency. The improvement of millimeter-wave power amplifier means longer available working distance, and stronger anti-jamming capability, and better communication, no matter for the radar systems or communication systems. The approach of power combing is an effective solution for greater output power, which is restricted by the output of single device. At present, the circuit combination structure and spatial combination structure are often adopted. The planar circuit combination structure is usually based on microstrip circuit, but the loss of microstrip line is huge at millimeter-wave frequency. Furthermore, the number of accessories is restricted because the circuits need too much to hold the accessories.This dissertation analyzes the power dividing and combining networks in detail, which are used in millimeter-wave frequency. And a novelty planar power combination structure, which is composed by H-plane Tee junction, H-plane 3dB waveguide directional coupler and waveguide-to-microstrip Transition, is put forward. This kind of combination structure has less insert loss and higher combination efficiency than the usual planar circuit combination structure based on microstrip line, and it is thinner than spatial combination structure, so it could be used in many systems.A practical back-to-back power dividing and combining network with the frequency range of 34~37GHz is produced, and the insert loss in this range is less than 2dB and the reflection loss is better than 15dB. Based on the researching and experimenting, a planar power combining amplifier is made with 4 AMMC5040 amplifier accessories. It can provide output power more than 27.41dBm in the frequency range of 33~36GHz, and the peak output power is 27.93dBm at 35GHz. The average power combining efficiency is greater than 80% while the maximum power combining efficiency is 96.2% at 33.5GHz.