What Is Radio Propagation?

Radio refers to electromagnetic waves propagating in all free space (including air and vacuum). It is one of the limited frequency bands. The upper limit frequency is 3THz (terahertz) and the lower limit frequency is not uniform. In various RF specifications, 3KHz is common ~ 3THz (ITU-International Telecommunication Union), 9KHz ~ 3THz, 10KHz ~ 3THz ^[1] .

The earliest use of radio in navigation used Morse telegrams to transfer information between ships and land. Radio has many application forms, including wireless data networks, various mobile communications, and

Band (frequency band)	symbol	Wavelength range	Frequency Range	Application range
Ultra Long Wave (Very Low Frequency)	VLF	100000-10000m	3-30kHz	Coast: Submarine Communications Navigation
Long wave (low frequency)	LF	10000-1000m	30-300kHz	Medium-range communication in the atmosphere Underground rock formation communication Navigation
Medium wave (IF)	MF	1000-100m	300-3000kHz	broadcast Navigation
Short wave (high frequency)	HF	100-10m	3-30MHz	Long-distance shortwave communication Shortwave broadcasting
Ultrashort wave (VHF)	VHF	10-1m	30-300MHz	Ionospheric scattering communication (30-60MHz) Meteor trail communication (30-100MHz) Artificial ionosphere communication (30-144MHz) Communication to flying objects (airplanes, missiles, satellites) in and out of the atmosphere For television, radar, navigation,
Decimeter wave (UHF)	UHF	1-0.1m	300-3000MHz	Tropospheric Scattering Communication (700-1000MHz) Small capacity (8-12 channels) microwave relay communication (352-420MHz) Medium capacity (120 channels) microwave relay communication (1700-2400MHz) Mobile communication
Centimeter wave (UHF)	SHF	10-1cm	3-30GHz	Large-capacity (2500, 6000) microwave relay communication (3600-4200MHz, 5850-8500MHz) Digital communications Satellite Communications Waveguide communication
Millimeter wave (Very high frequency)	EHF	10-1mm	30-3THz	Communication as it penetrates the atmosphere

1.Communication field

The earliest application of radio was in the field of communication. People could use radio to transmit information over long distances for the first time. Modern wireless communication technology is more developed, and space communication technology is becoming increasingly mature. In daily life, mobile communication has become essential. Mobile communication has gone through the 1G (analog), 2G (digital), and 3G (high-speed) eras, and is currently in the period of 4G and 5G development. Since the 3G era, mobile communication has really brought people to the era of multimedia communications. Web pages, music, pictures, videos, etc. can all achieve a good customer experience on smartphones ^[9] .

2.Wireless LAN

Wireless Local Area Networks (WLANs) are widely used in medical, corporate network coverage, warehouse management, food and beverage retail, video surveillance, etc., and the identification of WiFi (Wireless Fidelity) hotspot networks is even more common in daily life. visible. In fact, WiFi is a trademark of WLANA (Wireless Local Area Network Alliance). WiFi is one of the WLAN technical standards; the coverage radius of WiFi can reach about 300 feet (about 90m), and WIAN (plus antenna) can reach 5km ^[9] .

3. Internet of Things (smart home)

In the era of the rapid development of information technology, the Internet of Things (IoT) is coming out, which can be literally understood as a network of connected objects. In plain terms, it is to connect all objects through the network. Obviously if connected through a wired network, This scenario is unimaginable. The Internet of Things is widely used in intelligent transportation, environmental protection, government work, public safety, safe home, intelligent fire protection, industrial monitoring, environmental monitoring, elderly care, personal health, flower cultivation, water system monitoring, food traceability, enemy detection and intelligence And many other areas. In the current daily life, the smart home is one of the typical Internet of Things applications, and its application prospects are very broad ^[9] .