Research On The Millimeter Wave And Terahertz Power Combining Passive Network

Terahertz wave refers to the electromagnetic wave in the frequency range of0.1?10THz.Because of its wide bandwidth,strong penetrating power and low photon energy,it has the potential to be applied to communication,medical examination,security inspection and other fields.In view of the great research value of terahertz,domestic and foreign institutions have conducted extensive research in this field in recent years.As a key link of terahertz power combining,the quality of power combining network has a great influence on the efficiency of the whole power combining system.The output power of the power combining amplifier is the superposition of each power amplifier unit through the power combining network.The actual output power of the power combining amplifier unit is limited by the number of amplifier units involved in the combining in the stacking process,the output power of each power amplifier unit,the phase consistency of each power signal during the combining and the combining path insert loss.In the output power of the amplifier unit,power signal phase certain cases,increasing the number of amplification unit involved in the combining,combining path loss decrease,ensure branch phase consistency is the key technology to realize microwave millimeter wave high efficiency power combining,this requires the power combining network has adopted by the branch number,small path loss,and the selection phase consistency;For the solid-state power combining amplifier,the combining network is also required to facilitate the integration of solid-state power devices,heat dissipation of power devices and system applications.Research and development of passive network with low path loss,high consistency of branch phase relation and easy manufacturing and assembly have become the key problems to be broken through in high frequency.The work content of this thesis is as follows:1.The high-order modes in the probe structure and their causes are analyzed.The effects of the high-order mode suppression cavity and the microstrip size in it are simulated and analyzed,and it is determined that the maximum waveguide broadside size that can be used in 220GHz band is 0.6 mm.The waveguide in this size will not produce high-order modes below 238GHz,and the broadside size can be appropriately reduced to increase the upper limit of the working frequency if the machining accuracy allows.2.The structure of waveguide-microstrip probe is explored more,and the probe suitable for terahertz band is simulated in detail.The performance and machinability of E-plane and H-plane probes were analyzed,and a variety of probes for 220GHz were designed to meet different conditions.3.Based on the waveguide T-junction theory,the E-plane T-junction,H-plane T-junction,ridged H-plane T-junction and the Magic-T are simulated respectively.The simulation results show that the four kinds of Bridges have good amplitude and phase consistency and very wide bandwidth,and the E-plane T-junction can reach the bandwidth of 20GHz.H-face T-junction and magic-T can achieve 40GHz bandwidth by adding ridges.The h-face T-knot and the H-plane T-junction with ridge are easy to be machined and realized.4.Based on the theory of waveguide ring bridge,this thesis summarizes the general design method of ring bridge suitable for terahertz band,that is,to enlarge the overall size of ring bridge by 3?/2,which can keep the characteristics of ring bridge and make it easier to process.In addition,the performance of ring bridge is optimized by adding ridge and matching.Based on this,this thesis puts forward a new structure of H-plane ring bridge,which has superior machinability,breaks through the technical difficulty of multiplex synthesis in terahertz frequency band without suitable synthesis structure.Simulation results show that the return loss of H-plane ring bridge is less than-20dB,the isolation is greater than 20dB,the output port amplitude difference is less than 0.5dB and the in-band flatness of the two output terminals is less than 0.5dB in the bandwidth of 210 GHz?213GHz.The measured results show that the S₁₁ of the physical structure is better than-10dB in the band.