Eight Millimeters Circuit Power Synthesis Technology Research

The dissertation studies the 8mm-band two-way power-combining techniques.At first, factors affecting the power combining efficiency are discussed. Then, three kinds of two-way power combiner- 3dB coupler, magic T and three-port lossless network are analyzed. In terms of the analysis, a waveguide-to-microstrip double probes trasition divider/combiner network which exhibits wide frequency band, low insertion loss and low return loss is fabricated. The insertion loss of a waveguide-to-microstrip transition structure is lower than 0.28dB and the return loss is lower than -15dB within the frequency range of 29～38GHz. In the end, the network is chosen to design a 8mm-band power-combining amplifier.The dissertation also analyzes the thermal distribution of the power-combning amplifier and simulates the steady-state temperature field because the dissipation of heat is a key factor which may influence the performance of power amplifiers considerably. In addition, this amplifier was capable of operating stablely during the temperature range of -40℃to 70℃.At -40℃, the measured 1dB output power exceeds 37.5dBm in the frequency range of 31～38GHz. At -40℃, the measured 1dB output power exceeds 34dBm in the frequency range of 31～38GHz. At room temperature, the measured 1dB output power exceeds 36dBm in the frequency range of 31～38GHz and the highest saturated output power is 38.87dBm( 7.71W) at 31GHz. The best power combining efficiency is 92% which appears at 36GHz.The dissertation comes up with a three-way power divider/combiner as well. The three-way power divider is composed of a 9 branch waveguide 4.7dB coupler and a 5 branch waveguide 3dB coupler. It is found the three-way power divider has an excellent performance of amplitude and phaze coherence and isolation of the signals on the three output ports.