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Antenna Part 3. Parameters of Antenna. Radiation Patterns: Omnidirectional, Directional & Isotropic.

Antenna Design playlist. Watch these video to understand more on Antenna Design.    • Antenna Part 1. Types of Antenna: Wir...   Antennas are fundamental components in wireless communication systems, enabling the transmission and reception of electromagnetic waves. The performance and functionality of an antenna are characterized by several key parameters. Radiation Pattern Gain Directivity Beamwidth Polarization Impedance VSWR (Voltage Standing Wave Ratio) Bandwidth Efficiency Front-to-Back Ratio Antenna Temperature Physical Size and Shape Near-Field and Far-Field Regions An antenna’s radiation pattern illustrates how it transmits radio frequency energy or power in different directions. This pattern is usually represented in a polar or Cartesian coordinate system, indicating whether an antenna can focus or disperse radio frequency energy. For instance, a good radiation pattern for a typical omnidirectional Wi-Fi router resembles a doughnut shape, as its radio waves radiate with equal power in all horizontal directions. Another example is the Yagi-Uda antenna, a type of directional antenna commonly used as a rooftop antenna for point-to-point Wi-Fi internet connections in rural areas. An omnidirectional antenna is a type of antenna that radiates equal radio power in all directions perpendicular to an axis (azimuthal directions). The power radiated is maximum in horizontal directions, dropping to zero directly above and below the antenna. When graphed in three dimensions, this radiation pattern is often described as doughnut-shaped. Omnidirectional antennas are widely used as nondirectional antennas because they radiate equally in all horizontal directions. The power radiated decreases with elevation angle, so little radio energy is directed into the sky or down toward the Earth. Omnidirectional antennas are commonly used for radio broadcasting and in mobile devices, such as cell phones, FM radios, walkie-talkies, wireless computer networks, cordless phones and GPS. They are also used for base stations that communicate with mobile radios, such as those used by police and taxi dispatchers, as well as for aircraft communications. Directional antennas send and receive signals in one direction only, usually in a tightly focused, very narrow beam. The signal pattern from a directional antenna has a cigar shape and looks the same from the top as from the sides. This shape is referred to as a lobe. Directional antennas usually have small side lobes, which are typically ignored because they don't significantly affect the signal. However, you should be aware of their existence in case you detect a small signal off to the side of a directional antenna. Directional antennas can radiate radio waves in beams when a greater concentration of radiation in a specific direction is desired. Similarly, receiving antennas can be designed to receive radio waves from only one direction. This can increase the power transmitted to receivers in that direction and reduce interference from unwanted sources. Directional antennas come in a variety of shapes, sizes, and designs, each tailored to its intended purpose. Common directional antenna designs include panel antennas, parabolic (or 'dish') antennas, sector antennas, grid antennas, and Yagi antennas. Each type has different applications, which are highly dependent on the specific setup. An isotropic antenna is a theoretical antenna that radiates equally in all directions, both horizontally & vertically, with the same intensity. It has a gain of 1 (0 dB) in the spherical space around it and an efficiency of 100%. An isotropic antenna is used as a reference to evaluate antenna gain. Many antennas specify gain in dBi (decibels over isotropic), which is the power transmitted by an antenna in a specific direction, divided by the power transmitted by an isotropic antenna emitting the same total power. Isotropic antenna is different from Omnidirectional antenna, which radiates equal power in all directions, having a spherical radiation pattern.