China
Africa
Explore chapters and articles related to this topic
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.
Solid-State Chemical Microsensors and Wireless Instrumentation
Published in Robert B. Northrop, Introduction to Instrumentation and Measurements, 2018
The RF communication bands can also be described in terms of their wavelength ranges as ULF (107 ≤ λ ≤ 108 m), ELF (105–107 m), VLF (104–105 m), LF (103–104 m), MF (102–103 m), HF (10–102 m), VHF (1–10 m), UHF (10−1–1 m), SHF (l0−2C–l0−1 m), and EHF (10−3–10−2 m). RF bands can also be described by frequency ranges: for example, VLF (10–30 kHz), LF (30–300 kHz), MF (300 kHz–3 MHz), HF (3–30 MHz), VHF (30–300 MHz), UHF (300 MHz– 3 GHz), and SHF (3–30 GHz).
A low-profile high gain U slotted wide band micro-strip antenna for 5G applications
Published in International Journal of Electronics, 2022
Shazia Ashraf, Javaid A. Sheikh, Umhara Rasool, Zahid Ahmad Bhat
After the insertion of curved construction at the tapering end of the feed-line, the 6th stage (ant 6 or proposed design) evolves from stage 5. Figure 9(a,b) demonstrate the stage’s respective reflection coefficient and E-plane gain. The RL vs. frequency curve of the proposed antenna dips at 26 GHz and 27 GHz, with S11 values of −24.19 and −21.97 dB, respectively. The introduction of rounded structures around the edges of the tapered end of the feed line increases the gain of the design to a value of 5.23 dBi. In comparison to all preceding stages, this stage displays an increase in impedance bandwidth to a value of 5.22 GHz and, unlike the preceding stages, produces an acceptable E plane peak gain of 5.28 dBi. The percentage impedance bandwidth achieved in this design is 18.64% in the range of 24.71 GHz to 29.93 GHz, which covers some spectrum of Ka-band (Ashraf et al., 2022) and is considered to fall in n-257 and n-258 NR operating band under ITU. This band of frequency is under investigation in most countries. Ka-band frequency spectrum opens up the market for wireless point-to-point microwave communication system, space telescopes close range targeting radars, vehicle speed detection, high-resolution systems, and military aircrafts. Satellite frequency of Ka-band spectrum uses circular polarisation, due to which the amount of rotational adjustment of feeding system becomes redundant. This band is designated as SHF (super high frequency) by ITU (International Telecommunication Union) and K-band by NATO letter designation. Table 2 briefly provides an overview of the different developmental stages of the antenna.