How can you identify the types of antennas used in telecommunications?

The minimum size have electrically small antennas, which impedance is tuned by metamaterials. The simplest metamaterials represent small resonant circuits located in order to create a medium shell around an electrically small antenna with the effective negative permittivity.

The comment in point one is incorrect. Although wavelength can be thought of a good indicator of the antenna size, it is quite rare to find antennas of the same length as the wavelength. A half wave dipole is half of a wavelength (as the name implies) and a quarter wave ground plane antenna has a vertical section (of the length implied in the name) but it also has perpendicular radials that are also a quarter wavelength. Antennas can (and often are) made significantly shorter than the wavelength by using inductors for example, this is for practical reasons. Antenna directivity leads to antennas being much larger than the wavelength, for example: Yagi and parabolic antennas,

First thing to identify an antena, is having a deep knowledge on RF theory and Antenna, theory. There's a lot of very good clasic books on the subject. From ARRL's Radio Amateur's Handbook, to Ramo Whinnery Van Duzer's Field and Waves, plus a lot of online courses. Antennas were a hot subject from the time of Marconi Any conductor is a more o less eficient antenna, so it's important to derermine. -Frequency range -Radiation characteristics. -kind of electromagnetic polarization -Impedance -Geometrical configuration -Bandwidth Antennas a are mix of maxwell equations and empiric knowledge, be aware.

Radiation pattern is formed by distribution of antennas currents, which radiate electromagnetic waves. Superposition of electromagnetic fields created by antenna currents forms the antenna radiation pattern.

The Antenna energy loss is caused by the impedance loss and mismatch of the distribution circuit, feeding lines, and phase shifters (for adjustable tilt) and diplexer (multiple frequency bands antenna). All contribute the loss between input energy / power and radiated power. Antenna Efficiency is measured as a ratio between power radiated and total power in to the antenna terminals.

Ideally antenna has only active part of impedance equal to the impedance of the feeding line. In this case all supplied energy is radiated without reflection at the side of the antenna.

Antennas can have different gain patterns, which describe how they focus or distribute their radiated energy. Some of most common gain patterns include: Directional Gain: These antennas focus their radiation in a specific direction, which increases signal strength in that direction but reduces it in other directions. Omnidirectional Gain: These antennas radiate equally in all directions, providing a 360-degree coverage pattern. Hemispherical Gain: These antennas radiate uniformly in a 180-degree pattern, typically used for covering a half-sphere. Sectoral Gain: These antennas have a sector-shaped radiation pattern, covering a specific angular segment of the azimuth.

In addition to the Antenna Gain, the Antenna Directivity and Antenna Efficiency should be considered. Hence, there is resistance loss due to distribution circuit and mismatch and radiation loss between input and radiated power. The antenna efficiency can be measured as ratio between the Directivity and the Antenna Gain. Antenna Efficiency is an important merit in evaluation of antenna. High efficiency can improve the quality and performance as coverage and capacity or reduce carbon oxide emission. Hence less power is needed to feed the antenna for the required service.