Design And Realization Of An S-band Radar Transmitter Featuring Solid-State Amplifier Driving CFA Tube

As the earliest microwave power devices successfully applied in radar transmitters,the electric vacuum amplifiers have many types of tubes.Power oscillation devices represented by vacuum transistors and magnetrons,and power amplification devices represented by klystrons,traveling wave tubes,and forward wave tubes have appeared one after another.The birth of these practical microwave power devices has also promoted the development of radar transmitter technology and succeeded in developing a multi-type electric vacuum system transmitter using the above devices as the core power devices.In most electric vacuum system transmitters,the electric vacuum amplifiers need to be heated by filaments,which can be as short as several minutes or as many as ten minutes.In a modern war where "time is life," anyone who can find the enemy first can take priority.The forward wave tube with cold cathode structure can realize almost instant start of the transmitter without filament heating.This feature is unmatched by other electric vacuum devices.Since the 1960 s,microwave power transistors have been rapidly developed and are rapidly becoming practical.As a result,all kinds of all-solid-state radar transmitters have mushroomed.The solid state transmitter uses a large number of power transistors to obtain the required high power output through multi-level power distribution synthesis.Even if there are individual or few power transistor failures,the output power of the whole machine will not have much influence,so the all-solid state The transmitter has a fault weakening characteristic,which is one of the significant advantages of the all-solid-state transmitter being distinguished from the transmitter of the electric vacuum system.The all-solid-state transmitter is easy to realize modularization and universal design,and the system has good scalability.Since its birth,it has attracted the attention of designers of transmitter systems and has been warmly welcomed by designers.The transmitters of the two systems have their own advantages and disadvantages.In high-power applications,the electric vacuum system transmitter has advantages.In the case of large duty ratio and long pulse applications,all-solid-state transmitters are more suitable.At present,two kinds of transmitter systems have achieved rapid development in competition with each other and have formed distinctive characteristics.This project aims to introduce a transmitter that can combine the advantages of the above two systems,and obtain a transmitter system for modern high-performance radars with excellent performance and affordable price.This thesis discusses and describes in detail how to design and implement an S-band solid state push forward wave tube radar transmitter.This transmitter system combines the advantages of a solid state amplifier and an electric vacuum amplifier.The resulting amplified chain system is characterized by its small size,light weight,and modest size,and its ability to quickly turn on the power without the need for filament preheating.At the same time,because the last-stage forward wave tube adopts a direct-current operational structure,it can work in the straight-through state.That is,under the condition that the cathode voltage is turned off,the front-stage power can be output through the forward wave tube almost without loss(the forward wave tube can be Considered to be a transmission waveguide)to achieve transmitter variable power output.The development and design work of this article centered on the realization of a transmitter with an output peak power of 125 kW,a working ratio of 5.5%,and a radio frequency pulse width of 200 ?s.The preamplifier,cathode high voltage switching power supply,extinguishing modulator,and dual cold source were introduced respectively.Cooling system design and other content.The developed transmitter fully satisfies the preset target at the beginning of the project.The transmitter has been successfully applied to a radar,and the operation is stable and reliable.The successful development of this system transmitter has laid a good technical foundation for the development of transmitters of the same type in the future.