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WLAN Technology Basics
Published in Rihai Wu, Xun Yang, Xia Zhou, Yibo Wang, Enterprise Wireless Local Area Network Architectures and Technologies, 2021
Rihai Wu, Xun Yang, Xia Zhou, Yibo Wang
The frequency range of a radio wave is known as the frequency band. WLANs operate in the 2.4 GHz (2.4–2.4835 GHz) or 5 GHz (5.15–5.35 GHz or 5.725–5.85 GHz) frequency band. Designed for Industrial, Scientific, and Medical (ISM) purposes, these frequency bands can be used without obtaining license or paying fees as long as the transmit power requirement (generally less than 1 W) is met and no interference is caused to other frequency bands. While such cost-free resources reduce WLAN deployment costs, co-channel interference can arise when multiple wireless communications technologies operate within the same frequency band. Available ISM frequency bands vary depending on country and region, and WLANs are required to use frequency bands in compliance with local laws and regulations.
Wireless Communication
Published in Dave Birtalan, William Nunley, Optoelectronics, 2018
RF frequencies range from the extremely low frequency (ELF) of 3 Hz to the ultrahigh frequency band (UHF) 300 to 3,000 MHz. Some typical RF wireless applications include cellular telecommunication, radio and television broadcasting, data networks, remote controls, and police and fire department radio communications. Microwave electromagnetic radiation ranges from 1 GHz, as recognized by the IEC and IEEE, up to the extremely high-frequency (EHF) range of 300 GHz. Microwaves are also used in telecommunications for point-to-point communications, for ground-stations-to-orbiting-satellites telecommunication applications, and wireless LAN protocols such as 802.11 (2.4 GHz). Radar, in a noncommunication application, utilizes microwave radiation to identify the range, speed, and characteristics of distant objects. Some of the wireless standards available are IEEE 802.15.1 (Bluetooth—2.4 GHz and 2.5 GHz, version 1.2), IEEE 802.15.4 (Zigbee—2.4 GHz), and IEEE 802.11a/b/g (WiFi—2.4 GHz b/g and 5 GHz/a).
Outlines of Radio Waves and Troposphere
Published in Pranab Kumar Karmakar, Microwave Propagation and Remote Sensing: Atmospheric Influences with Models and Applications, 2017
The term microwave is used as a generic name to include the centimeter, millimeter, and submillimeter region of the spectrum. Usually the frequency band extending from 3 to 300 GHz is named as the microwave band. But, in fact, manufacturers have subdivided the millimeter wave band (30–300 GHz) into the following overlapping frequencies: 18–26.5 GHz K band26.5–40 GHz Ka band33–50 GHz Q band40–60 GHz U band50–75 GHz V band60–90 GHz E band75–110 GHz W band90–140 GHz F band110–170 GHz D band140–220 GHz G band
Electromagnetic interference shielding effectiveness and microwave absorption performance of plaster mortars containing metal waste chips in X-band frequency range
Published in Journal of Microwave Power and Electromagnetic Energy, 2023
Kayhan Ates, Tolga Ziya Kocaer, Sukru Ozen, Niyazi Ugur Kockal
Studies show that industrial waste materials are essential in construction areas (Kockal 2013). Construction companies investigate alternative materials, such as waste materials, due to high energy demands and scarcity of raw materials (Kockal 2012). It is known that millions of tons of waste metal chips, which cause environmental pollution, are produced throughout the world (De Brito and Saikia 2013). The usage of waste metal chips can be applied as an aggregate in mortar and concrete. Also, some construction materials play a significant role by means of EMI shielding properties in wireless communication-sensitive buildings (Cakir et al. 2017). Therefore, electromagnetic pollution can be controlled. In light of this, the presented study investigates the EMI shielding effectiveness and electromagnetic absorbing capability of the plaster mortar samples containing various metallic waste chips in the X-band. This frequency band is widely used in satellite communications, radars, and military applications (Gupta and Nyan-Hwa 2019). Furthermore, the apparent porosity and the compressive strength of the samples were evaluated. The rest of this article was organized as follows. The preparation of samples, firstly, was presented. Theoretical background and computational method were introduced subsequently. Following that, the results of the electromagnetic shielding effectiveness were depicted in the next chapter. Finally, the results were concluded.
A high-precision electromagnetic technique for modeling and simulation in inhomogeneous media
Published in Waves in Random and Complex Media, 2020
In the following examples, we use the plasma plume as the inhomogeneous medium, which is derived from the experimental data [17]. The computational domain size is 2 × 2 × 1 m. The antenna excited by a Gaussian pulse is located at the point (0, 0.32, 0.016). The frequency band of interest is from 0 to 2 GHz, a frequency band referred to as UHF (300MHz–1 GHz) and L (1–2 GHz) band which are mainly used for the satellite positioning, the satellite communications and the mobile communications. The observation points, around a circle of an observation radius of 0.48 m, are all located at the cross-section at x = 0. And when using SO-FDTD to determine the values of electromagnetic fields, the grid size of the FDTD model for each numerical experiment is 16, 8, 4, 2, 1.6, 1, and 0.5 mm, respectively. The UPML thickness is 10 grid points.
Filterless frequency octupling circuit using dual stage cascaded polarization modulators
Published in Journal of Modern Optics, 2019
Gazi Mahamud Hasan, Mehedi Hasan, Karin Hinzer, Trevor Hall
One goal of future communication systems such as 5G is the delivery of multi-Gb/s services to customers. As a consequence, deployment of high capacity wireless communication networks is in demand to deliver such super broadband services and to support ever-growing data traffic from wireless mobile customers. The capacity of the systems can be expanded only with the use of a suitable broadband frequency spectrum. The congested lower frequency bands enforce the use of the millimetre wave band which lies in between 30 and 300 GHz. With a 270 GHz bandwidth, it can support a substantially larger traffic volume compared to today’s technology. Nevertheless, millimetre wave generation using conventional electronics is costly and complicated due to the limited frequency response of electronic devices and the involvement of multi-stage frequency multiplication. The spectral purity is deteriorated by the emergence of undesired harmonics in the multiplication process. Optical millimetre wave signal generation techniques are becoming more attractive because they offer broad bandwidth, high stability and tunability.