Theoretical Analysis On The Characteristics Of Microwave Couping Into The Cavity With Slots And Into The Circuit And Experimental Study Of Microwave Injection Into The Basic Circuit

The investigation of the interaction between high power microwave and the electronic system is an important topic in the area of the applications of high power microwave and the reinforcement of the electronic systems. The effects of microwace on cavity with slots and basic circuit are investigated by theoretical analysis, numerical simulation, and microwave injection experiment. The process of microwave-slot coupling in the cavity, microwave coupling into circuit, and the microwave effects on circuit transmission are studied, and the model and evaluation of microwave effects on system with metal enclosure are also provided, which is helpful to expore the effects of microwave on cavity with slots and basic circuit. The details of invesitagtion are as follows:1. The coupling characteristics of the slot and array slot are investigated in detail in order to improve the shielding performance of the cavity with slots. With complementary antenna theory, the resonant frequency, the resonant and enhancement factor, and the resonant bandwidth are derived with slots being rectangular, circular, annulus, media packing, and array. The expressions have wide application in studing the coupling characteristics of any metal cavity with slots and the results are helpful to the design of the cavity of the system. Using the analysis of the procession of the air ionization in the narrow rectangular slot, the relation between the breakdown time and peak incident electric field is derived to explain the tail erosion effects and the frequency upshifts. The analysis results can be used to the investigation of the widnow breakdown of the high power microwave and the design of plasma limiter for preventing high power microwave. The shielding performance of the cavity is improved 6 dB by the media coating, which is another microwave protection method in the microwave-slot coupling. The systemic and overall analysis of microwave-slot coupling gives a strong support for the investigation of microwave effects on the electronic systems and the improvement of shielding performance of electronic systems.2. The microwave coupling into the circuit is theoretically studied. The coupling performance of cables and one-line print circuit are studied by using the equivalent transform line model, and the key bandwidth of the coupling frequency is derived. By using the Laplace transformation, the influence of the plasma on the microwave coupling and transmission is explored, indicating the frequency upshift of the microwave and the random heating phenomenon, which is a new challenge to electromagnetic compatibility of the electronic system.3. Based on the theoretical analysis, simulation and the experiment of microwave injection into the circuit, the microwave effects on the buffer and analog-digital converter circuit are investigated on the basic circuit level. The core chip of the ciruit is 74HC04 or 74LVCU04A inverter. The study is concentrated on the parameters of the injected microwave pulses, such as amplitude, carrier frequency, pulse width, and repetition frequency, changing the microwave effects on the circuit operation at three levels, which are linear interference, nonlinear disturbance, and damage effect. The analysis of the amplification gain of the circuit voltages, the process of the inverter shutting up and the relationship between the width of microwave pulse and power threshold of damage indicate the mechanism of linear interference, nonlinear disturbance, and the damage effect respectively. Under the conditions of the fixed temperature, the threshold of the effective injected microwave power for reducing the noise tolerance in the output signal by 40 % is 26 dBm for 74HC04 and 23 dBm for 74LVCU04A, when the carried frequency of injected microwave frequency is below 3GHz. The threshold of the effective injected microwave power for reducing the noise tolerance in the output signal by 50 % is 4 to 6 dBm, which is lower than that for reducing the sampling interval of the output signal by 10%, with which the response changes from the linear interference to the nonlinear disturbance. The threshold of the effective injected microwave power increases with the carrier frequency, which is similar to the linear interference and nonlinear disturbance. The threshold of the microwave effects on the circuit is almost independent to the repetition frequency of the injection microwave in linear disturbance regim. The threshold of nonlinear disturbance has a strong relation to the pulse width of the injection microwave, and the inflection point of the relation curves is about 40 to 70 ns, which is related to the current shutting up. The microwave effects on basic circuit are the extension to the study of the elementary device and the complex circuit.4. The results of injected microwave experiment are treated by the statistic analysis and the overall effects are studied by the effects analysis and evaluation. The statistic analyses, consisting of the statistic analysis on the no obvious influence variable, the fitted linear line analysis for the linear interference, the analysis of the believable region of measurement data, the analysis of the sample requirement of the experiment, and the analysis of the lower believable limit of probability of the completely destroying effect, making sure the reliability of injected microwave experiment results and giving a further improvement suggestion to the study of microwave effects on electronic system. The transmission functions matrix of basic circuit with cavity enclosure is studied by the theoretical analysis and network algorithm, which is useful for the high power microwave radiation experiment on the circuit.