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Transmission and Propagation of Electromagnetic Waves
Published in Sibley Martin, Modern Telecommunications, 2018
For mobile applications, we need an omnidirectional antenna. One such is the λ/4 monopole which acts as a λ/2 dipole (Figure 5.18) by virtue of the image conductor in the ground plane. The ground plane does not have to be fixed to the physical ground. Instead, a metal sheet, such as the roof of a car, can be used. The impedance of a λ/4 monopole is 36 Ω and its gain over an isotropic radiator is 5.14 dB. The radiation pattern is a circle so it receives and transmits signals from all horizontal directions. It is possible to change the impedance of the monopole to 50 Ω by using radial ground wires angled at 45° to the vertical or by using a transformer.
Antennae
Published in Le Nguyen Binh, Wireless And Guided Wave Electromagnetics, 2017
An antennae tower is a tall structure to support antennae as aerials for telecommunication and broadcasting. The first tower was constructed in Munich Olympic Park for the television broadcasting purposes of the 1972 Olympics. A dipole antenna is a simple antenna usually constructed from two wires in opposite phases positioned end to end with respect to each other. A horn antenna is a type of directional antenna shaped like a horn. An omnidirectional antenna is an antenna system that radiates power uniformly in all directions in one plane. A parabolic antenna is an antenna shaped like a parabola in one or both planes.
Radio Frequency Utilization
Published in Gilbert Held, Wireless Mesh Networks, 2005
Antennae can be subdivided into two general categories, omnidirectional and unidirectional. An omnidirectional antenna radiates in all directions. In comparison, a unidirectional antenna radiates in only one direction. That direction has a variance, referred to as a beam width, which indicates the directionality of the antenna.
Energy efficient optimal hop transmission using minimum power least cost algorithm in cooperative routing for wireless sensor network
Published in Automatika, 2023
Immanuvel Arokia James K., Manjula P., Guga Priya G., Karthikeyan A.
Radio receivers and transmitters, as a rule, require antennas, keeping in mind the end goal of coupling electrical association with the electromagnetic field. Radio waves are generally electromagnetic waves that help motions through space or air at the speed of light with practically no transmission misfortune. Radio transmitters and receivers are utilised to pass on signals in broadcast (audio) radio, TV, portable Wi-Fi (WLAN) data networks, and remote control gadgets, among numerous others. Reception apparatuses are typically omnidirectional. They generally emanate energy similarly every which way, or directionally, where energy transmits more along one bearing than others. It's physically difficult to get a totally uniform omnidirectional antenna. Reception apparatuses, as a rule, send little energy upward or downward; however, they for the most part have a uniform radiation design in the horizontal plane [7].
Analysis of Omnidirectional Antenna Systems Using Cavity Model
Published in IETE Journal of Research, 2021
Nibash Kumar Sahu, Sanjeev Kumar Mishra
Fields patterns of two types of linearly polarized omnidirectional antenna systems (VPOAS and HPOAS) are derived. The proposed derivations are validated by simulating the designs using CST software and fabricating the VPOAS. The derived theories are well agreed with simulation and measured results. From the derived theories and simulation, it is confirmed that VPOAS and HPOAS are providing vertical and horizontal polarization, respectively. Both the systems are resonating at 2.22-GHz with 32-MHz of impedance bandwidth. VPOAS and HPOAS are providing a peak gain of 4.2 and 5.4 dBi respectively. VPOAS and HPOAS can be used in NAG-missile telemetry when receiving antennas (ground station antenna) are vertically and horizontally polarized respectively. The advantage of this paper is the presentation of a novel, simple and efficient theoretical model for the evaluation electric field radiated by a vertically and horizontally polarized conformal microstrip antenna. The analytical formulation introduced here can be extended for the case of circularly polarized conformal microstrip antenna array.
A Novel Approach to Efficient Resource Allocation in NOMA Heterogeneous Networks: Multi-Criteria Green Resource Management
Published in Applied Artificial Intelligence, 2018
Faramarz Nikjoo, Abbas Mirzaei, Amin Mohajer
Assume that is the mth base station, where in this notation, the macro cell is indicated with m = 1 (we have only one MBS in each region) and the other values denote the PBSs. Assume that N is the randomly distributed UE in the area covered by the network. Each UE is associated with just one base station. All base stations and UE are represented by single omnidirectional antenna nodes. Also, the general perfect channel state information (CSI) is assumed to be accessible. The index denotes the jth UE. In accordance with the NOMA schemes, the signal transmitted by base station m is where in which is the binary index and indicates the UA. if the jth UE will be assigned to base station m and else, . denotes the assigned downlink transmission power and denotes the data flow of the jth user. If UE j is served by base station m, the signal received by UE will be: