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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
The far field region is the most important, as this...
- Directivity
Directivity is explained, which is a measure of the...
- 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
If the dipole antenna's length becomes close to one wavelength, the input impedance becomes infinite. This wild change in input impedance can be understood by studying high frequency transmission line theory .
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
Geometrical Theory of Diffraction (GTD): Antenna system is many wavelengths. GO’s disadvantage is overcome by including diffraction mechanism (high frequency). Integral Equations (IE): Unknown induced currents (explained by magnetic field) are solved by IE (Numerically MoM). EFIE (for all regions) and MFIE (for closed region)
The book provides a broad coverage of antenna types and phenomena, for operations at very low radio frequencies, as well as frequencies up to those of submillimeter wavelengths. Unlike most university-level antenna textbooks, it does not require prior skills in electromagnetic theory, sophisticated mathematics, or computer programming.
ANTENNAS. Antennas couple propagating electromagnetic waves to and from circuits and devices, typically using wires (treated in Section 3.2) or apertures (treated in Section 3.3).
