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Radiowave Propagation
Published in Indrakshi Dey, Propagation Modeling for Wireless Communications, 2022
HF band (3–30 MHz) is used in Ionospheric long haul hops for radio broadcasting services, aeronautical and maritime mobile communications. VHF Band (30–300 MHz) is used in long distance receiving for audio and video broadcasting, aeronautical and maritime radio communications, over-horizon radio communication by tropo-scatters, radar and radio navigation services, analog cordless telephone, radio paging services and lower earth orbit (LEO) satellite systems, while UHF band (300–3,000 MHz) is used for TV broadcasting, cellular mobile radio services, mobile satellite, GPS, astronomy communications, radar and radio navigation services. SHF band (3–30 GHz) is used for radar systems and military applications, TV satellite broadcasting and remote sensing from satellites. EHF band (30–300 GHz) is being planned for broadband-fixed wireless access, future satellite and high-altitude platform applications. Similarly, micro-metric and nano-metric bands are being planned for space radio communications, satellite communications, laser and infrared radio communications, and fiber optics cable networks.
Microwave technology as a viable sanitation technology option for sludge treatment
Published in Peter Matuku Mawioo, Novel Concepts, Systems and Technology for Sludge Management in Emergency and Slum Settings, 2020
Microwave is a part of the electromagnetic spectrum with wavelengths (λ) ranging from 1 m to 1 mm and frequencies between 300 MHz (λ =1m) and 300 GHz (λ =1mm) (Haque, 1999; Tang et al., 2010; Remya and Lin, 2011). Three microwave frequency bands exist comprising the ultra-high frequency (UHF: 300 MHz (λ=1 m) to 3 GHz (λ=100 mm)), the super high frequency (SHF: 3 GHz (λ=100m) to 30 GHz (λ=10mm)) and the extremely high frequency (EHF: 30 GHz (λ=10 mm) to 300 GHz (λ=1 mm)). Microwaves have higher energy but shorter wavelengths than the radio waves. Conversely, they have lower energy but longer wavelengths than infrared, visible, ultraviolet (UV), X-rays and gamma-rays (Figure 4-1).
Radio Location, Radio Navigation, and GPS Systems
Published in John G. Webster, Halit Eren, Measurement, Instrumentation, and Sensors Handbook, 2017
For practical purposes, the radio wave spectrum is broken into eight bands of frequencies; these are very low frequency (VFL) <30 kHz, low frequency (LF) 30–300 kHz, medium frequency (MF) 300 kHz–3 MHz, high frequency (HF) 3–30 MHz, very high frequency (VHF) 30–300 MHz, ultrahigh frequency (UHF) 300 MHz to 3 GHz, super high frequency (SHF) 3 to 30 GHz, and extremely high frequency (EHF) 30–300 GHz.
Pistachio hull as an alternative pectin source: its extraction and use in oil in water emulsion system
Published in Preparative Biochemistry & Biotechnology, 2023
Sehra Barış, Aysel Elik, Fahrettin Göğüş, Derya Koçak Yanık
Pectin is a complex hetero-polysaccharide and mainly contains α-(1→4) linked D-galacturonic acid (at least 65% galacturonic acid).[2] It is found in the cell membrane of plants, between the cells, or in the middle lamella region.[3] The most widely used pectin extraction method is the conventional acid extraction method in which hot water acidified with a mineral acid is used. Although the acid extraction method is considered economically advantageous, new methods are being explored in the extraction to reduce the harmful effect of mineral acid uses. Microwave-assisted extraction,[4] ultra-sonication,[5] ultrahigh pressure,[6] and super-high frequency electromagnetic field[7] are some of these methods.