Research On Novel Radial Power Combining Method Based On Vortex Mode

Solid-state power amplifiers which have advantages in operating bandwidth,operating voltage,and reliability have been continuously studied and developed,and gradually replace the traveling-wave tube amplifiers in space applications.However,in the high-millimeter-wave and terahertz band,the power level of an individual solid-state power amplifier is restricted,which is hard to meet the requirements of related system applications.Therefore,power combining technique takes an essential part in breaking through the limitation of the individual solid-state device and realizing the high-efficiency power combining source.Radial power combining,which not only has the advantage that the combining efficiency does not decrease obviously with the increased combining channels,but also has good amplitude and phase balance,ultra-broadband,and the potential to be utilized at very high-frequency bands,is a research hotspot in the power combining technique.After studying and summarizing the development of the radial power combining technology,it is found that the radial power combining theories in microwave and low millimeter waves are developed based on three circumferential symmetrical modes,resulting in the tiny structure size that is hard to be processed,poor suppression of the interference mode,limited selection of the radial operating mode,limited operating frequency of radial power combining,and other problems in the higher-frequency band.In consideration of the above-mentioned issues,this thesis starts from the symmetry of the electromagnetic field mode and aims to construct a new radial operating mode suitable for the millimeter-wave and terahertz band.Finally,a new radial power combining method based on the vortex mode is proposed.The main focus of this thesis is shown as follows:The electromagnetic field distributions of the circumferential symmetrical modes and non-circumferential symmetrical modes in the transmission line of the guided wave system are studied.By analyzing the basic characteristics of the vortex electromagnetic wave,the concept of the electromagnetic vortex mode is introduced into the guided wave system and radial power combining.And a new radial operating mode set based on the vortex mode is constructed in the transmission line by means of linearly superimposing the modes.Besides,the excitation conditions of the vortex mode in the radial power combining network are analyzed based on the vector voltage transfer matrix theory.According to the analysis,a new radial power combining method based on the vortex mode is proposed.Taking the W-band as the verification band,according to the proposed novel radial power combining method,a 16-way radial power combiner/divider is designed,in which the circular waveguide vortex TE₁₁ mode is chosen as the operating mode.The simulated results depict that across the 90 to 98 GHz band,the insertion loss of the radial power combiner/divider is less than 0.13 d B,and the power combining efficiency of 97%can be achieved.Based on the designed novel radial power combiner/divider,a 32-way radial power combining amplifier is fabricated.The measured results under the pulsed condition show that the power amplifier delivers an output power of greater than 63 W with the combining efficiency greater than 74%and power added efficiency close to 9.6%from92 GHz to 96 GHz,which verifies the practical efficiency of the new radial power combining method based on the vortex mode in the power combining amplifier.