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Before we can design an antenna or discuss antenna types, we must understand the basics of antennas, which are the fundamental parameters that characterize an antenna. So let us learn something. We'll start with frequency and step through radiation patterns, directivity and gain, and ultimately close with an explanation on why antennas radiate.
- Frequency
Frequency is one of the most important concepts in the...
- Radiation Pattern
A radiation pattern defines the variation of the power...
- Field Regions
In the immediate vicinity of the antenna, we have the...
- Directivity
A normalized radiation pattern is the same as a radiation...
- Antenna Efficiency
Being a ratio, antenna efficiency is a number between 0 and...
- Antenna Gain
The gain of a real antenna can be as high as 40-50 dB for...
- Beamwidths and Sidelobes
In addition to directivity, the radiation patterns of...
- Impedance
Antenna impedance relates the voltage to the current at the...
- Frequency
The finite-length dipole antenna is discussed. The currents on the structure are considered, and the input impedance is plotted versus size. The concept of a resonant dipole antenna is discussed.
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.
An intuitive tutorial of antennas and antenna theory. This website is designed to present a comprehensive overview of antennas, from design, to measurement and theory. Unnecessarily complicated math is avoided throughout.
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
An antenna is a device that couples currents to electromagnetic waves for purposes of radiation or reception. The process by which antennas radiate can be easily understood in terms of the way in which accelerating charged particles or time-varying currents radiate, which is discussed in Section 10.1.
Antenna Effective length is used to determine the polarization efficiency of the antenna. Definition − “The Effective length is the ratio of the magnitude of voltage at the open terminals of the receiving antenna to the magnitude of the field strength of the incident wave front, in the same direction of antenna polarization.”
