Research Of The Modeling Of Several Special Apertures And Their Electromagnetic Characteristics

There are a lot of apertures(or cracks, slots, ducts, holes and so on) in(or on) all kinds of electronic equipments. There are many kinks of the apertures with the structures in the living environment, such as windows, doors, ventilation pipes, and so on. The electromagnetic characteristics of the aperture is an important research area in electromagnetic compatibility. Especially when the modern electronic warfare is getting worse, protecting our electronic devices and attacking the enemy’s become the key to win the victory over the enemy. Among these, the aperture is a top priority. Apertures which are used in the microwave devices are also very widespread. They are used in the microstrip antenna which is a popular communication antenna today. They are used as a coupling structure, also as a radiator. Although people use powerful computers to analyze the electromagnetic characteristics of the structures nowadays, but because of the complexity of the actual environment, and usually the aperture is connecting two or more areas which are the same complex, so that it is still difficult to analysze such a problem. So, the aperture has been an interesting topic in electromagnetics for many years.So far, many scholars have done a lot of work on the aperture problems which are simple or complicate shapes. There are a few successful models for complicate slots, such as arbitrary shape in flat plane, having depth, of filled with different materials. And their electromagnetic characteristics are analyzed. But there are rare researches on the multi-scale and multi-region apertures. The apertures are this kind in the living environment, such as arbitrary shaped3D aperture,3D eletrical thin-long slots,3D aperture arrays and apertures which are backed by microwave networks. This thesis concentrates on the modeling of the multi-scale and multi-region apertures, studying their eletromagnetic characteristics. And it wishes to be used in the design. The main contents and several innovations are shown bellow:1. The equivalence of the equivalent problems is discussed in detial. And the selections of the different equivalence surface are deeply analized. A few rules are proposed for optimal modeling.2. Based on the model of the double2D slots backed by microwave network which is illuminated by a plane wave, an extended model which is combined with the mode matching technique is developed.3. By using the uniqueness theorem and the equivalence principle, a new model which is capable analyzing the arbitrary3D shape aperture is developed. The integral fromulations are deduced. Then, the matrix equations are formed by using the moment procedure. And the equivalence magnetic currents which are on the aperture’s equivalence sruface are solved. The electric currents which are on the inside and outside of the cavity are calculated, and the electric fields as well. A3D aperture which is on the edge of the cavity is analyzed by applying the model.4. An improvement of the new model is developed. The optimal model is capable handling the multi-scale and multi-region apertures. And a few canonical examples are analyzed under the application of the optimal model.