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Antenna – Definition in Electronics

The amount of signal received from a remote transmission source is essentially geometric in nature due to the inverse distribution of square, which leads to the concept of effective surface. This measures the power of an antenna by comparing the power it generates with the amount of power in the original signal, measured by the signal`s power density in watts per square meter. A half-wave dipole has an effective area of 0.13 λ 2 {displaystyle 0.13lambda ^{2}}. If more power is needed, you can`t just enlarge the antenna. While this would intercept more energy from the signal due to the above considerations, it would significantly reduce the output as it moves away from the resonance length. In roles that require higher performance, designers often use multiple elements that are combined with each other. Now that we`ve seen a little more about antennas in general and why we use antennas, let`s go ahead and take a look at the different types of antennas. There are different types of antennas and each literature article has its own classification of antennas. Most of the radiated field, which covers a larger area, is the main lobe or the main lobe. This is the part where the maximum radiated energy is present. The direction of this lobe indicates the directivity of the antenna. In radio communication systems, we use wireless electromagnetic waves as a channel.

For these purposes, antennas of different specifications may be used. The size of these antennas depends on the bandwidth and frequency of the signal to be transmitted. In computer applications and wireless Internet, the most common type of antenna is the antenna machine used for satellite communication. Antennas are usually only convenient at microwave frequencies (above about 3 GHz). The shell consists of a paraboloidal or spherical reflector with an active element in focus. Upon receipt, the shell collects the HF from a remote source and focuses it on the active element. When used for transmission, the active element emits RF, which is collimated by the reflector for delivery in a certain direction. Capacitor plates can simply be conductors or wire equivalents.

The fields emitted by radial currents tend to cancel each other out in the far field, so the far fields of the antenna of the capacitor plate can be approximated by the infinitesimal dipole. Two long wires are connected in the form of a V to make a V-shaped antenna. The two long wires are excited with a 180° phase shift. As the length of these wires increases, the gain and directivity also increase. An antenna meter or base plate is a structure made of conductive material that improves or replaces the floor. It can be connected to natural soil or isolated. In a monopolar antenna, this contributes to the function of the natural soil, especially when variations (or limitations) in the characteristics of the natural soil interfere with its proper functioning. Such a structure is usually associated with the reconnection of an unbalanced transmission line such as the shielding of a coaxial cable. The improvement in the radiation pattern of an antenna is always evaluated by the isotropic radiation of that antenna. If the radiation is the same in all directions, it is called isotropic radiation. The intensity of the radiation, when measured closer to the antenna, is different from what is far from the antenna.

Although the area is far from the antenna, it is considered effective because the intensity of the radiation is still high. But if we look at an isotropic antenna, its power density will be the same at all points in the radiation sphere. Therefore, the average power of an antenna as a function of radiated power A phased array consists of two or more single antennas connected to each other via an electrical network. It is often a series of parallel dipole antennas with a certain distance. Depending on the relative phase introduced by the array, the same combination of dipole antennas can function as a “wide array” (directed perpendicular to a line that connects the elements) or as a “final fire network” (directed along the line that connects the elements). Antenna arrays can use any type of basic antenna (omnidirectional or weakly directed), such as: Dipole, loop or slotted antennas. These elements are often identical. In general, the term effective aperture or effective area is associated with the receiving antenna. The opening or effective surface of an antenna is the measure of an antenna`s ability to extract energy from the electromagnetic wave. These hilly arrays are unidirectional antennas with high gain. The main objective of this network is to increase the radiated power and provide a high directional beam by avoiding power losses in other directions.

When the EM wave reaches the receiving antenna, it triggers movement in the charges present in the conductor. Thus, mobile loads generate electricity inside the conductor. An antenna is generally thought of as a combination of different short conductors. A transmitting antenna excited by an rf electrical signal, then the charges present in the conductor begin a balanced movement. The end result is that the resonance antenna only effectively introduces a signal into the transmission line if the frequency of the source signal is close to that of the antenna design frequency or one of the resonance multiples. This makes resonant antenna designs inherently narrowband and useful for a small frequency range. The range of the far field is far enough away from the antenna to ignore its size and shape: it can be assumed that the electromagnetic wave is a purely radiating plane wave (the electric and magnetic fields are phased and perpendicular to each other and to the direction of propagation). This simplifies the mathematical analysis of the radiated field.

The following figure shows the geometry of the parabolic reflector. The point F is the focus (power is given) and V is the vertex. The line that connects F and V is the axis of symmetry. PQ are the reflected rays, where L represents the direct straight line on which the reflected points are located (to say that they are collinear). According to the above definition, the distance between F and L is therefore constant with respect to the focused waves. A necessary condition for the above reciprocity property is that the materials in the antenna and transmission medium are linear and reciprocal. Reciprocal (or bilateral) means that the material has the same response to an electric current or magnetic field in one direction as to the field or current in the opposite direction. Most of the materials used in antennas meet these conditions, but some microwave antennas use high-tech components such as insulators and circulation pumps made of non-reciprocal materials such as ferrite. [10] [11] These can be used to give the antenna a different behavior during reception than during transmission,[10] which can be useful in applications such as radar.


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