Shortwave Combo Different Frequency Power Combiner Circuit Structure And Simulation Studies

As its characteristic of good survivability, easy network building and cheap costing, shortwave communication takes an important part of military telecommunication, which is used to send telegraph, data and static image. With the development of the shortwave communication, it has a broad prospect in civil use.Power synthesis technology has been widely used as a key technology of the shortwave communication. The primary purpose of this paper is studying the theoty and the experimental method of a 2-way combiner of different frequencies. The combiner makes two input signals of different power and frequencies into one output signal, which can be sent by single shortwave antenna to reduce the quantity and the area of antenna site. The subject carries out the ability of using single shortwave antenna, a part of apparatus to combine high power, to send the input power from multichannels, which is much suitable for the warship under the bad electromagnetic environment. It is very useful for the high-power broadband shortwave communication to achieve the all solid stat. The main contents in this paper are described as follow:1. Base on the theory of transmission line transformer, analyze its working principle and make the impedance matched by adjusting the length of transmission line and the inductance of the NiZn magnetic core of their own models, with which can extend the upper limit frequency and the lower limit frequency. By discussing how to choose the core material and the size of the core under the high-power condition, the solution to reduce the magnetic core loss is obtained.2. Accomplish the method of power combiner of different frequencies based on the theory of the same frequency. It includes two parts: the impedance transtormation and the power combination. The circuit parameter is determined by the requirement of isolation degree, insertion loss, vswr and the power capcity of the magnetic core. Base on the traditional analysis of telegraph equation for the classical 1:4 impendance transformation, establish the equivalent model of transmission line transformers including the coupling condition between the transmission line. Summarize the Z parameter equations by using the analysis of asymmetric transmission line method to discuss the situation when the current of transmission line transformers is not equal because of the effect of the magnetic core. Take the input impedance as the example to confirm a design method of engineering approximation by comparing the difference between the theoretical analysis to the practical result.3. Establish the thermal design method of forced air cooling, discuss the design method of the radiator and the air fan by theoretical calculation and computer simulation. While considering the environment design, margin design and the derating use of the power resistor in order to ensure the reliability index, the final product structure is acquired.A real-environment test shows that the product has steady performance, and the technique indices can fully meet the design requirements.