Electromagnetic Compatibility Research And Design For High-Power Microwave Devices And Circuits

With the rapid development of microwave technology, the need for microwave devices in the areas of microwave communications, microwave navigation, guidance, remote control, satellite communications and military electronic warfare continues to grow. The more strained radio communication frequency resources, denser frequency intervals for various communication systems, higher communication frequencies and wider frequency band raise unprecedented rigorous requirements for the structure design and implementation of microwave devices, e.g., modern microwave and millimeter-wave transceivers raise higher requirements for front-end passive components in the aspects of reduction of attenuation and suppression of various interference signals.Now, miniature, light-duty and high power microwave circuits and their electromagnetic compatibility research and design has become quite an important research aspect. Developing high-power, high-performance, small-size microwave passive and active components, implementing high-standard electromagnetic compatibility design as well as improving the stability and reliability of the components and system is one of the key technologies that is urgently needed in the area of microwave and millimeter-wave communications.This paper focuses on two areas, one is the electromagnetic compatibility design for high-power microwave devices including microwave power module (MPM) and microwave oven magnetron, the other is the miniaturization for microstrip filters and antennas. Based on the principles of electromagnetic fields and microwave technology, this paper firstly analyzed the principle, structure and performance design of MPM in depth, and then proposed a solution to its stability and implemented electromagnetic compatibility research and design for its main components such as switching power supply. This paper also implemented simulation on electromagnetic properties of continuous-wave magnetron and provided a solution to suppress the harmonics in microwave oven magnetron. Besides these, based on the antenna and filter theories, this paper involved microstrip slot patch antennas design which are suitable for broadband communications and band elimination filter design that could suppress the second and third harmonics in broadband communications in accordance with the electromagnetic compatibility requirements for microwave circuits.The innovative work in this paper includes:1. This paper analyzed the causes of electromagnetic radiation of microwave power module as well as principles and properties of switching power supply used in MPM. Based these, this paper implemented electromagnetic compatibility research on the switching power supply circuits and proposed electromagnetic compatibility solution for MPM and filter circuit of amelioration for switching power supply of MPM.2. In order to solve the EMI problems met by continuous-wave magnetron that current microwave oven uses, according to the European microwave oven standards, this paper used a large-scale electromagnetic PIC simulation software to research the dynamic characteristics of continuous-wave magnetron such as output power and spectrum at 2.450GHz by simulating the interaction processes between its high-frequency fields and electron under working conditions, and then proposed improved anti-EMI measures for continuous-wave magnetron.3. According to the band-elimination characteristics of detected ground structure (DGS) and characteristics of microstrip structure, this paper researched and developed a novel, small-size and non-symmetrical T-type DGS dual-band band elimination filter on the basis of dumbbell-shaped, Spiral-shaped, T-shaped DGS filters. The novel filter cascaded multiple units and had the advantages of deep stop-band rejection and small size. This filter was produced and tested, and the measurement results agreed well with the simulation results. Furthermore, this filter could successfully suppress the second and third harmonics in the Bluetooth frequency band, and reduce the interference and radiation to the system and environment.4. This paper researched and designed two novel and compact microstrip antennas, optimized the overall size, gap length, width and feed points. These two microstrip bow-tie slot antennas, which work in the Bluetooth frequency band, had the advantages of wide bandwidth, well-matching for impedance, high radiation efficiency. Measurement results and simulation results were in good agreement. Additionally, the results showed that the feed points could tune the antenna's center frequency subtly, which could provide good debugging performance in the antenna's actual production.