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Further Studies of Electromagnetic Waves in Spherical Geometries
Published in Guillermo Gonzalez, Advanced Electromagnetic Wave Propagation Methods, 2021
The field produced by a horizontal electric dipole can be calculated using the reciprocity theorem. The reciprocity theorem finds application in circuit theory and in antenna theory. In circuit theory the reciprocity theorem basically states that in a linear circuit if a voltage in a branch (say at the input of the circuit) produces a current in another branch (say Io at the output of the circuit), then the same voltage applied at the output will produce the current Io at the input. In antenna theory, the theorem states that if a current in antenna 1 induces a voltage Vo in antenna 2, the same current in antenna 2 induces the same voltage Vo in antenna 1.
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Published in Philip A. Laplante, Comprehensive Dictionary of Electrical Engineering, 2018
received signal strength indicator (RSSI) i, j Z + (the set of nonnegative integers) is given by T (z 1 , z 2 ) = C × In 1 z 1 - A 1 -A3 B1 B2 +D -A2 In 2 z 2 - A 4 (2) reciprocity (1) a consequence of Maxwell's equations, stipulating the phenomenon that the reaction of the sources of each of two different source distributions with the fields generated by the other are equal, provided the media involved have certain permeability and permittivity properties (reciprocal media). Referring to reciprocal circuits, reciprocity states that the positions of an ideal voltage source (zero internal impedance) and an ideal ammeter (infinite internal impedance) can be interchanged without affecting their readings. (2) in antenna theory, the principal that the receive and transmit patterns of an antenna are the same. reciprocity in scattering law according to which the source and detector points can be exchanged, providing the source amplitude and phase are preserved. reciprocity theorem in a network consisting of linear, passive impedances, the ratio of the voltage introduced into any branch to the current in any other branch is equal in magnitude and phase to the ratio that results if the positions of the voltage and current are interchanged. recloser a self-contained device placed on distribution lines that senses line currents and opens on overcurrent. Reclosing is employed to reenergize the protected line segment in the case of temporary faults. Reclosers have the capability for fast tripping for fuse saving, and slow tripping to allow sectionalizing fuse operation for faults on laterals. The recloser will retrip on permanent faults and go on to lockout. Reclosers are suitable for pole mounting on overhead lines.
General Properties
Published in Michel Nevière, Evgeny Popov, Light Propagation in Periodic Media, 2018
The concept of reciprocity is a basic law of electromagnetism, which applies from the elementary theory of networks in electrokinetics to antennas theory [I.53]. Roughly speaking, it states that the intensity of an electromagnetic signal is not affected by an interchange between the source and the detector. Applied to diffraction gratings, the theorem can be formulated in the following way.
A Brief Review on mm-Wave Antennas for 5G and Beyond Applications
Published in IETE Technical Review, 2023
Paikhomba Loktongbam, Debasish Pal, A. K. Bandyopadhyay, Chaitali Koley
Path loss in mm-wave communication is high compared to the same at lower frequencies, and this loss is also frequency selective. There are mainly two types of losses in mm-wave communication. The first is scattering loss, and the second is absorption loss. Scattering loss is a natural phenomenon for propagating EM waves. This loss is present even in microwave frequencies. The second one is gaseous absorption loss. This occurs because gas molecules are excited by mm-wave and start vibrating. Hence EM energy is converted to kinetic energy and is lost. It is essential to mention here that between 0.2 and 10 THz, the attenuation is dominated by water vapor present in the atmosphere. Attenuation due to rain and fog has a minor effect. This scenario is exactly the opposite of that IR (Infrared) propagation. In IR propagation, fog and smoke significantly affect path loss. Even in the THz regime also atmospheric attenuation depends on altitude and temperature. Due to this high atmospheric losses role of the antenna becomes more and more critical. According to Friis transmission formula [38], the power supplied to a load of a receiving antenna is given by where, , are output power, input power to the transmitting antenna, operating wavelength, distance between the transmitter and receiver, gain of the transmitting antenna, gain of receiving antenna, position of the (in spherical co-ordinate) receiving antenna, position of the (in spherical co-ordinate) transmitting antenna, path power transmission factor and polarization coupling efficiency, respectively. The output power to the load is directly proportional to the gain of the transmitting and receiving antenna. With the help of the reciprocity theorem [38], the same antenna can be used for the transmission and reception purposes. Under this condition, the output power is proportional to the square of the antenna gain. With other parameters remaining constant, the output power is inversely proportional to the square of the distance between the two antennas. Due to the limitation of the source power (Pin), it is necessary to increase the antenna's gain in the mm-wave system to cover the longer distance. Gain is related to directivity by, are the transmitting antenna gain, radiated power by the antenna, input power to the antenna, and directivity of the transmitting antenna, respectively. Hence highly directive antenna is required to overcome the effects of the environmental loss factor. Generally, the lens antennas are used for high directivity in mm-wave frequencies. Silicon has commonly been used as a substrate for the design of lens antennas in mm-wave [39–44] frequencies. Despite high directivity, as it is not compact in size, it is not easy to integrate the same for on-chip applications.