Антенни устройства. Изследвания в зоните на електромагнитно излъчване

Abstract

An antenna is an intermediate link between the radio transmitting or receiving device and the surrounding area. The antenna is a device that serves to radiate electromagnetic energy in the form of radio waves in the space and respectively to receive electromagnetic waves. In the first case, we are talking about a transmitting antenna, and the second one about a receiving antenna. The purpose of the transmitting antenna is to convert the transmitter's high-frequency current into a freely propagating electromagnetic wave. The role of the receiving antennas is to take part of the energy of the electromagnetic waves that reach them and trigger the receiver. The emitted field from the antenna is determine by the Pointing vector and shows the electromagnetic radiation area. Near the antenna, it is imaginary and has components on the three coordinate axes (θ, φ, r) considered in the spherical coordinate system to determine the position of a point in the three-dimensional space. Intensity of the field decreases faster than 1/r in the immediate vicinity of the antenna and proportional to 1/r in the distant zone. The Pointing vector in the distant zone is real and has two components (θ, φ) in the coordinate system.