Research On 220GHz Triple Harmonic Mixing Technology

Terahertz wave is an electromagnetic wave with a frequency between 100 GHz and10THz.Compared with microwaves and light waves,it not only has the advantages of both,but also has unique advantages in detection,communication and imaging,which makes terahertz technology a hot research topic.In terahertz technology,the receiving system is particularly important,and the mixer is an important part of the receiving system,which has a significant impact on the overall performance of the system.The third harmonic mixer is important for the application of terahertz technology,which makes it easier to implement the local oscillation signal in the mixer and also makes the whole transceiver system simpler and miniaturized by reducing redundant modules.In this thesis,the third harmonic mixer at 220 GHz is investigated.Firstly,the harmonic mixing principle is studied in depth by reading a lot of domestic and international literature on harmonic mixers and odd harmonic mixers.The working principle and equivalent circuit of Schottky diode,which is the core of terahertz mixer,are also studied in detail,and a three-dimensional electromagnetic model based on the physical structure of the diode in terahertz band is established.In this thesis,a homophase series Schottky planar diode is used,and a combination of " electric field " and " circuit " is used for accurate modeling.In the 220 GHz third harmonic hybrid circuit,the RF signal is converted from rectangular waveguide to fin line by the cosine single-side fin line transition structure,and the impedance matching is achieved by fin line and coplanar waveguide for the RF signal and the local oscillation signal,respectively.The overall circuit of the mixer is jointly simulated by combining the "electric field " and " circuit " methods.The simulation results show that the frequency conversion loss of the third harmonic mixer is better than 20 d B in the frequency range of 200GHz-240 GHz,and the best frequency conversion loss is 12 d B.Then the processing test of the mixer is conducted,and the test results show that the frequency conversion loss of the third harmonic mixer is better than 24 d B in the frequency range of 200GHz-240 GHz when the LO is 73 GHz,and the best frequency conversion loss is15 d B.At present,there is relatively little research on the third harmonic mixer compared with the subharmonic mixer,and this thesis provides some experience for the research of terahertz odd harmonic mixer,and will continue to conduct in-depth research on odd harmonic mixer in the future.