Introduction：
The radio spectrum consists of all frequencies that have electromagnetic radiation, which spreads energy in the form of waves and propagates through space. Longer wavelengths and lower frequencies make up the radio spectrum. Shorter wavelengths and higher frequencies make up the spectrum. The portion of the spectrum that we can see is called the visible spectrum, however there are many tools utilized that allow us to communicate and create images using the electromagnetic spectrum in some way. Below we will learn how the radio spectrum is divided into frequency ranges.
The radio spectrum is divided into different categories based on frequency
Frequency Range Classification of Radio Spectrum - Low to High Frequency Classification Definition Chart
The radio spectrum can be divided into a number of different categories based on frequency, which can be listed in full with just one image above, or you can see all the radio division bands in the list below:
- Extreme Low Frequency ELF (Extremely Low Frequency) : 3Hz-30Hz
- Super Low Frequency (SLF) : 30Hz-300Hz
- ULF (Ultra Low Frequency) : 300Hz-3kHz
- Very Low Frequency (VLF) : 3kHz-30KHz
- Low Frequency (LF) : 30kHz-300KHz
- Medium Frequency (MF) : 300KHz-3MHz
- High Frequency (HF) : 3MHz-30MHz
- Very High Frequency (VHF) : 30MHz-300MHz
- Ultra High Frequency (UHF) : 300MHz-3GHz
- Super High Frequency (SHF) : 3GHz-30GHz
- EHF (Extremely High Frequency) : 30GHz-300GHz
The purpose of EMC electromagnetic compatibility testing:
The purpose of EMC electromagnetic compatibility testing is to ensure that the above radio spectrum categories will not be affected by human self-produced electronic products, with the 5G commercialization, the use of frequencies up to 5GHz, harmonic frequencies can reach 10 times the frequency of more than 10 times the frequency of the impact of other electronic devices is huge and unavoidable, so to carry out electromagnetic compatibility testing provisions for the electronic products of various industriesTesting of interference component limit lines using conducted interference transmitting equipment, which also provides forTesting of interference component limit lines using radiated emission equipment, and allow itself to accept the effects of that magnitude to ensure that each electronic device product will work properly.
II. Classification of signals that can be propagated in the radio spectrum:
The radio spectrum is characterized by the propagation characteristics and the amount of information that a signal can carry. Generally, a signal sent using a higher frequency can only travel a shorter distance, but it has a higher data-carrying capacity. These physical characteristics of the spectrum limit the range of applications for which any particular band is suitable. Some spectrum (e.g., in the (UHF) band 300-3000 MHz) is known to be suitable for a wide variety of services and is in high demand.
Analog signals:
There are two important types of transmissions to understand: analog and digital. Analog signals transmit information (sound, video, or data) in a continuous wave that varies in intensity and frequency directly with the transmitting source.
Analog Signal Waveforms - Propagating Intensity and Frequency Changes as Continuous Waves
Digital signals:
Digital signals transmit information converted to 1s and 0s, which are formatted and sent as electrical pulses. Advantages of using digital signals include greater accuracy, reduction of noise (unwanted signals) and increased capacity to send information.
Digital Signal Waveforms - Propagated as electrical pulses More accurate, less interference
The electromagnetic spectrum is a limited natural resource. Spectral waves naturally propagate in all directions. A transmitter can be focused to transmit its signal to a single designated location. Similarly, a receiver can be focused to maximize signal reception. The receiving antenna can still detect unintended signals that may interfere with the intended signal reception. To avoid signal interference problems, multiple users cannot simultaneously transmit radio signals at the same frequency and in the same direction. As soon as one user stops transmitting a signal on a portion of the spectrum, another user can immediately reuse it. Spectrum is scarce; the use of a frequency at any given time and place precludes its use for any other purpose.
Abbreviated names and explanations of common electromagnetic spectrum frequency bands:
The following names and explanations are defined by the NSA.
- VLF: Very Low Frequency "whistle" dynamic spectrometer.
- LF. Stereo Waves (SWAVES) uses radio imaging to study coronal mass ejections.
- MF. Amorphous beacons utilize IF radio frequencies to transmit directional information to aircraft. Improvements in amorphous beacon technology.
- HF. The QuickScat scatterometry satellite captures images of sea breeze patterns on Earth.
- VHF. Utilization of VHF bands to study the thickness of sea ice.
- UHF. Use the UHF system as a backup to the voice communications system.
- SHF. The Defense Satellite Communications System (DSCS) satellite constellation utilizes self-focusing frequencies to deliver critical information to the military and government.
- EHF. The mission of the Wilkinson Microwave Anisotropy Probe (WMAP) is to discover the geometry, content, and evolution of the universe by producing various maps of the sky.
- Infraed:GOS satellites use the infamous technology to observe and track hurricane paths.
- UV:The Solar and Heliospheric Observatory is studying the Sun - from the core to the outer corona to the outer winds.
- X-ray. The GOS satellite uses an X-ray imager (SXI) to photograph and study the Sun.
- Gamma Ray/Cosmic Ray. Instead of using gamma rays or cosmic rays to study the universe, scanning uses X-rays to study gamma rays and cosmic rays.
- 3G four standards and frequency bands:CDMA2000, WCDMA, TD-SCDMA, WiMAX, 1880MHz-1900MHz and 2010MHz-2025MHz.
- 4G frequencies and bands are:1880-1900MHz, 2320-2370MHz, 2575-2635MHz.
- 5G frequencies and bands:3300-3400 MHz (principle ceiling indoor use), 3400-3600 MHz and 4800-5000 MHz