Research On Key Technologies Of Millimeter-Wave And Terahertz Band Power Combining

In the field of microwave,both vacuum electronic device and solid-state power device are commonly used for power amplification and solid-state power device is widely applied due to its advantages such as low noise,low operating voltage,high reliability and ease of mass production.However,with the increase of operating frequency,the output power of a single solid-state power amplifier device is extremely limited,which cannot meet the current communication system’s demand for high power.Therefore,the development of power combining is particularly important.The key to power combining at high frequency is to have a passive power combining network with low insertion loss and good amplitude and phase consistency.The focus of this thesis is to achieve high combining efficiency while ensuring circuit stability and achieving wide operating bandwidth in the presence of numerous combining ways.The specific research results include the following aspects:1.A two-way power combiner based on a planar magic-T is designed,fabricated and tested in Ka-band（26.5～40GHz）.The measurement results show that the return loss of three ports is greater than 19d B,the isolation between the rectangular waveguide output ports is greater than 15d B and the insertion loss is less than 0.2d B.Then,a four-way and a eight-way power combiner based on a planar magic-T are simulated and the return loss of the total port is better than 17d B.The return loss of the output port of the microstrip line is greater than 18d B.The isolation between adjacent output ports is greater than 14d B and the isolation between non-adjacent output ports is greater than 23d B.After that,a back-to-back four-way power combining structure based on a planar magic-T is fabricated and tested.The measurement results show that the insertion loss is about3.15d B and the overall return loss of the input and output ports is greater than 15d B between 28GHz and 32GHz.2.A radial power combiner based on circular waveguide TE₀₁ mode with"V-shaped isolation"port is designed,fabricated,and tested in Ka-band（32～38GHz）.The insertion loss is less than 0.5d B in the operating frequency band,the return loss of the total port is greater than 18.5d B and the phase imbalance is less than±9°.Compared to traditional radial power combiner,the return loss of the output ports has been significantly improved from 6d B to 15d B.3.A back-to-back four-way power combining network based on a planar magic-T and E-plane waveguide-microstrip transition is simulated in the terahertz frequency band（200～220GHz）.In this operating frequency band,the return loss of the input and output ports is generally better than 21.5d B and the insertion loss is less than 0.03d B.