Electromagnetic spectrum
From HvWiki
The electromagnetic spectrum is the range of all possible electromagnetic radiation. Also, the "electromagnetic spectrum" (usually just spectrum) of an object is the range of electromagnetic radiation that it emits, reflects, or transmits.
At the top of this list are shorter wavelength (and hence higher frequency) waves. Note that there is some overlap in the spectrum. It is possible, for example, for a photon to be classified as soft x-ray and extreme ultraviolet. This is especially true in the ultraviolet and infrared range, where boundaries are not standardized.
| Name | Frequency Range | Wavelength Range | Sub Bands | Remarks |
|---|---|---|---|---|
| Gamma Rays | > 30 EHz | < 10 pm | None | This is ionizing radiation. |
| Hard X-Rays | 300 PHz - 30 EHz | 1 nm - 10 pm | None | Ionizing radiation, frequently used in medical and industrial applications. |
| 30 PHz - 300 PHz | 10 nm - 1 nm | None | Ionizing radiation, less powerful than hard X-rays. |
| 9.67 PHz - 30 PHz | 31 nm - 10 nm | None | Powerful ultraviolet radiation. |
| 1.50 PHz - 9.67 PHz | 200 nm - 31 nm | None | Powerful ultraviolet radiation. |
| Near Ultraviolet (UV) | 749 THz - 1.50 PHz | 400 nm - 200 nm |
| Exposure in this range causes sunburns. |
| Visible Light | 428 THz - 749 THz | 700 nm - 400 nm | Usually divided into colors. | This is the only part of the electromagnetic spectrum that humans can see. |
| Infrared (IR) | 300 GHz - 428 THz | 1 mm - 700 nm | No standard sub bands, commonly divided as follows:
| Terahertz radiation falls inside the IR band. |
| Extremely High Frequency (EHF) | 30 GHz - 300 GHz | 10 mm - 1 mm | Microwave (1 GHz - 300 GHz)
Microwave Bands:
Amateur Radio Bands:
| Used for radio astronomy, and line of sight data links. |
| Super High Frequency (SHF) | 3 GHz - 30 GHz | 10 cm - 10 mm | Wireless USB will operate from 3.1 to 10.6 GHz. | |
| Ultra High Frequency (UHF) | 300 MHz - 3 GHz | 1 m - 10 cm | In this range of frequencies, propagation is line of sight only. Even foliage starts to become a serious obstacle. Microwave ovens operate in this range, at 2.45GHz. 802.11b/g also operates here, from 2.4-2.5GHz. | |
| Very High Frequency (VHF) | 30 MHz - 300 MHz | 10 m - 1 m | FM Broadcast Band (88-108 MHz)
Amateur Radio Bands:
| Long range propagation is less reliable at the lower frequency end of the VHF range, and rare at the high frequency end. This range of frequencies is normally used for line of sight or just beyond. |
| High Frequency (HF) | 3 MHz - 30 MHz | 100 m - 10 m | Shortwave (3 MHz - 30 MHz)
Shortwave Broadcast Bands:
Amateur Radio Bands:
| Reliable worldwide ionospheric propagation occurs in this range. Populated by broadcasters, Amatuer Radio operators, and various government and military transmitters. Used for both communications and long range radar. |
| Medium Frequency (MF) | 300 KHz - 3 MHz | 1 km - 100 m | Mediumwave Broadcast Band (530 KHz - 1710 KHz)
Shortwave Broadcast Bands:
Amateur Radio Bands:
| Provides short-range groundwave propagation during the day, and often provides long-range ionospheric propagation at night. |
| Low Frequency (LF) | 30 KHz - 300 KHz | 10 km - 1 km | Longwave Broadcast Band (148.5 kHz - 283.5 kHz) | In addition to broadcasters, the LF range is populated with differential GPS (DGPS) transmitters, non-directional beacons (NDBs), and LORAN transmitters. |
| Very Low Frequency (VLF) | 3 KHz - 30 KHz | 100 km - 10 km | None
| The ITU does not regulate radio waves below 10 kHz. Similarly, the FCC does not regulate radio waves below 9 kHz. This range is commonly used to communicate with submerged submarines, due to its ability to penetrate seawater to several meters. |
| Ultra Low Frequency (ULF) | 300 Hz - 3 KHz | 1,000 km - 100 km | None | Used for radio communications in mines, due to excellent earth-penetrating properties. |
| Super Low Frequency (SLF) | 30 Hz - 300 Hz | 10,000 km - 1,000 km | None | Common power grid frequencies of 50 Hz and 60 Hz are in this band. The US and Russian deep-sea communications systems Sanguine and ZEVS operate here, at 76 and 82 Hz respectively. |
| Extremely Low Frequency (ELF) | 3 Hz - 30 Hz | 100,000 km - 10,000 km | None | Rarely used due to extreme antenna size required. |
