Terahertz High-speed Real-time Communication System Based On OFDM And Related Modulation Devices

In the electromagnetic wave spectrum,the frequency band of terahertz waves lies between the short wavelength band and the infrared wavelength band.Terahertz wave has the characteristics of high bandwidth,high information content,high spatiotemporal coherence,and good directionality.Therefore,Terahertz communication technology will be widely used in the fields of military defense and civil communications,with very broad scientific research value and application prospects.In terms of power consumption and system complexity,fully digitized,miniaturized,and highly simplified terahertz highspeed communication systems have unique advantages.However,currently,terahertz communication systems generally have problems such as complex system architecture and low modulation rates.In order to solve the above problems,this thesis designs a terahertz differential feed modulator based on fin lines and Schottky diodes,and conducts experiments on terahertz direct modulation communication systems using this modulator.At the same time,a terahertz high-speed real-time communication system based on OFDM is studied.The main research content of this thesis is:1.The research on terahertz direct modulation devices based on single branch and fin line differential feed has been carried out.In order to improve the modulation efficiency of the modulator,a differential feed method is adopted.In order to increase the bandwidth of the modulator,the modulator is designed using the large bandwidth characteristics of the fin line;And through the volt-ampere characteristics of Schottky diodes,the effect of conduction and blocking is achieved by controlling the power on.Static testing of the designed differential feed terahertz modulator based on fin lines has been carried out.The maximum modulation depth can reach 23 d B at 165 GHz,the insertion loss is only 1.9 d B,and the available bandwidth coverage range is 128-196GHz(Frequency coverage spans two standard waveguide ports,WR-7 and WR-5.1),meeting the basic requirements for the performance of the required modulator components in terahertz direct modulation communication systems.Using this modulator,a terahertz high speed OOK direct modulation communication system based on low complexity is built.The system operates at 160 GHz and uses direct detection and reception technology to achieve eye pattern transmission at 32 Gbps over a 3m communication distance,the theoretical distance for replacing a high gain antenna can reach 100m2.A terahertz high-speed real-time communication system based on OFDM has been completed.First,a single channel 220 GHz terahertz wireless communication system experiment was conducted.The system uses 16 QAM modulation,and IQ mixing modulation to achieve a distance of 250 meters to achieve a rate of 20 Gbps of 4k video transmission;On this basis,a terahertz uplink and downlink wireless communication system was completed,using IQ mixing modulation to work in the 220 GHz frequency band,achieving a total rate of 41.6 Gbps of 4k video transmission over a communication distance of 630 m.And designed a corresponding modular and miniaturized portable chassis.This thesis has conducted research and analysis of simulation design,from processing testing to communication system construction.The above research provides a good foundation and technical support for solving the problems of low modulation rate and short communication distance in terahertz communication systems.