A study of the interference stripe phenomenon caused by electromagnetic wave propagating in multi-layered medium

The interference stripe appears in the penetrating scan experiments of multi-layered medium detection, the experiments are implemented by the single-frequency plane array or the moved single transmitting/receiving (T/R) antenna. Based on the medium boundary conditions of Maxwell equations from the classic electromagnetic theory, the interference stripe phenomenon is studied in the paper. And the commercial simulation software CST Microwave Studio is used to construct the simulation models. Under the near-field condition, the propagation and reflection of electromagnetic wave in the monolayer medium and the multi-layered media are simulated. Two situations, the electromagnetic wave being perpendicular and oblique to the dielectric plate, are specially carried out to compare. The echo waves received by the antenna changed position are analyzed. It can be found that there is no interference stripe when the incident wave is perpendicular to the dielectric plate. However, the interference stripe phenomenon will arise when there is a certain angle between the incident wave and the normal of the dielectric plate. This can be proved by the scan experiments results. The existence of the interference stripe will cause serious disturbance to the target echo, because the former is greater than the latter. So it will affect the performance of target detection and identification. From the point of view of the electromagnetic wave incidence and reflection theorem, the existence reason of this phenomenon is discussed. The relationship between the incident angle and interference stripe is illuminated. The study of this phenomenon will be helpful for the signal processing of the plane array and the moved single T/R antenna scanning system, such as the interference stripe phenomenon reducing and the target imaging quality improving. It can also be helpful for solving some problems encountered in the highways detecting, archeology, geology survey, etc.