Investigation On The Radiated Electromagnetic Interference To The Performance Of Microwave Active Circuits

Electromagnetic interference (EMI) analysis of electrical and electronic systems is becomingmore important in modern electronics industry. As the key components of the electronic systems andthe wireless communications, the microwave active circuits are related to the entire system’sperformance directly. In this thesis, the hybrid field-circuit method is employed to investigate theradiated electromagnetic interference to the performance of microwave active circuits. The maincontents are presented as follows:1. Using the hybrid field-circuit simulation, radiated susceptibility of microwave active circuitsis analyzed. A decoupling analysis approach is presented to evaluate the radiated susceptibility of atypical power amplifier circuit enclosed in a slotted cavity. Simulated results demonstrate thatexternal electromagnetic field can cause the gain degradation of power amplifier. Furthermore, twomeasures for improving the electromagnetic interference effects are proposed. The coupling cause bythe mismatch transmission network terminal is not considered in this method.2. The port coupling caused by the mismatch transmission network terminals is considered.Hybrid S-matrix approach is investigated. The hybrid S-matrix approach is based on identifying andextracting the antenna and transmission line (TL) modes from the induced transmission line voltage.The TL modes are incorporated into the hybrid S-matrix which allows the microwave network to beported to a circuit solver. The antenna modes are applied as constant voltage sources at thecorresponding ports. Three examples are analyzed, and the results are compared to the HFSSsimulation results to verify the effectiveness and high efficiency of this approach.3. Experimental research on the radiated electromagnetic interference to a low noise amplifier(LNA) is carried out. The effectiveness of the aforementioned approaches in this thesis is verified bycomparing the typical test results with the results of these approaches.