ANALYSIS AND PLACEMENT OF YAGI-UDA ARRAYS IN MULTI ANTENNA RECEIVING SYSTEM

摘要

In many situations the space limitations dictate the placement of the receiving antennas at a closer proximity to each other. The unavoidable electromagnetic coupling effects may degrade (or improve) the performance of the antennas and this must be taken into consideration while placing the antennas together. In this paper, the mostly used television receiving antenna (Yagi-Uda) is considered as a typical example of receiving antennas. The Yagi-Uda arrays on a building top at various configurations are analysed and the electromagnetic coupling bttween the antennas is calculated. The aim of this paper is to evaluate the changes in the gain of each antenna in the presence of other receiving antennas in various configurations. The approach is to calculate the input impedance of the antennas in presence of other antennas, which depends upon the self impedance and the mutual impedance between the antennas. The input impedance is then used to calculate the gain of each antenna in multi antenna receiving environment. The technique used is Method of Moments, the efficient way to characterise the actual currents on the antenna elements.