-diameter Antenna Near-field Mutual Coupling Simulation Analysis

The phenomena that many electronic apparatus are placed in a limited area become more and more common along with the science and technology is developed rapidly. As the main transmitting and receiving port of electromagnetic power, it is easiest to form the mutual interfering between two antennas, namely power mutual coupling. The mutual interfering between antennas can affect the function of electronic apparatus, even destroy the apparatus. So the research on antenna mutual coupling has been one of important problems in the area of Electromagnetic Compatibility.The thesis focuses on the research on the mutual coupling about two typical aperture antennas system, pyramidal horn system and paraboloid antennas system, respectively. The former is composed by two pyramidal horns which are placed in face-to-face configuration, and the later is composed by two paraboloid antennas which are placed in back-to-back configuration, respectively. Through the analysis of mutual coupling to the two antenna system, the problem of calculation the power coupling between two antennas which are placed in any position is solved.As for pyramidal horn system, the thesis firstly discusses three methods used to compute antenna radiation pattern in the near-axis zone: Plane Wave Spectrum, Surface Current, and Aperture Integration. As an example, the thesis use Aperture Integration method to compute near-field pattern of typical pyramidal horn. Then, the thesis introduces a way to compute far-axis zone field of pyramidal horn—Geometrical Theory of Diffraction, and uses it obtain the near-field pattern of the antenna. At last, the thesis computes near-field mutual coupling between two pyramidal horn antennas E-plane and H-plane, respectively.As for paraboloid antenna system, the first step is to finding out the edge-diffracted points of transmission antenna by a combination of coordinate transformation and GTD two-point method. The next step is to computing the edge-diffracted field of receiving antenna's aperture. The following step is computing the receiving field of waveguide feed's aperture by ECM, and figure out the receiving power, consequently. The last step is to deducing the expression of mutual coupling by applying the definition of power coupling.Some calculated results are compared with the simulation results of software, most of which are shown to be in good agreement.According to analysis the results, it is shown that mutual coupling will be reduced by adjusting the ubiety of two antennas suitably, and make it to gratify the need of Electromagnetic Compatibility. The result can be used as guidance for the installation disposition of multiple antennas system.