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25 paź 2024 · In radio communications, the length of an antenna is closely related to the frequency of the signal it is designed to transmit or receive. The general rule is that the higher the frequency, the shorter the wavelength, and as a result, the required antenna length decreases.
1. Definition of the Antenna and Wave-Motion The radio antenna may be defined as the interface between a circuit in which electrical power is constrained to follow conducting paths, and electromagnetic radiation travelling freely through space. The antenna may convert power in the circuit into radiated energy or vice versa, forming either
antennas. Some antennas may also be described as "omnidirectional", which for an actual means that it is isotropic in a single plane (as in Figure 1 above for the x-y plane). The third category of antennas are "directional", which do not have a symmetry in the radiation pattern.
Antennas are devices for radiating or receiving radio waves; but: •. Antennae are sensitive organs of insects. •. At GHz frequencies, a physical limitation for applications in wireless commu-nications is given by the atmospheric attenuation of electromagnetic waves due to water vapor and absorption by gases [9]; see Fig. 2.1.2.
Antennas & Projects 20.1 ANTENNA BASICS very ham needs at least one antenna, and most hams have built one. This chapter, by Chuck Hutchinson, K8CH, covers theory and construction of antennas for most radio amateurs. Here you’ll find simple verticals and dipoles, as well as quad and Yagi projects and other antennas that you can build and use.
The third edition of Antenna Theory is designed to meet the needs of electrical engi- neering and physics students at the senior undergraduate and beginning graduate levels, and those of practicing engineers.
Antennas 101 “Don’t Be a 0.97 dB Weakling!” The Basics. Ward Silver NØAX. Antennas radiate (or receive) because electrons are accelerated (or are caused to accelerate) in the antenna’s elements. Radio or electromagnetic waves are both an E- (electric) and H- (magnetic) field. Electrons move parallel to E-fields.
