A brief look at the electromagnetic spectrum
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A brief look at the electromagnetic spectrum l.jpg

A Brief Look at the Electromagnetic Spectrum


This PowerPoint presentation was designed as one of a series of lunch seminars for employees at Virginia Diodes, Inc. It contains many images pulled from the internet without attribution. This slide show is placed on our website so that our employees may access it at any time. Visitors to our website may use this PowerPoint file free of charge and without attribution. However, if you make any alterations or additions that might be deemed offensive to anyone, please remove any references to VDI. The slide show was put together rather quickly, so there may be some unintentional errors. There are a few references and images that are included for humor.

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Relationship Between Wavelength and Frequency

Speed of light: 299,792,458 meters/second (exact by definition)

186,282 mile/s

(Speed of light) = (Wavelength) x (Frequency)

c = ln

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Acronyms used in the Band Designations

ELF: 3-30 Hz, (Extremely Low Frequency)

SLF: 30-300 Hz (Super Low Frequency)

ULF: 300Hz-3KHz (Ultra Low Frequency)

VLF: 3-30 KHz (Very Low Frequency)

LF: 30-300 KHz (Low Frequency)

MF: 300KHz – 3MHz (Medium Frequency)

HF: 3-30 MHz (High Frequency)

VHF: 30–300 MHz (Very High Frequency)

UHF: 300 MHz – 3 GHz (Ultra High Frequency)

SHF: 3-30 GHz (Super High Frequency)

EHF: 30-300 GHz (Extremely High Frequency)

IHF: 300-3000 GHz (Insanely High Frequency) (just kidding)

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Standard time and frequency stations

JJY in Japan (40 kHz and 60 kHz)

MSF in Rugby, England (60 kHz, 5 km, 3.1 miles)

WWVB in Colorado, USA (60 kHz)

HBG in Prangins, Switzerland (75 kHz)

DCF77 near Frankfurt am Main, Germany (77.5 kHz)

LORAN (LOng RAnge Navigation) is a terrestrial navigation system using low frequency radio transmitters that use the time interval between radio signals received from three or more stations to determine the position of a ship or aircraft. The current version of LORAN in common use is LORAN-C, which operates in the low frequency 90 to 110 kHz band.LORAN is being widely displaced by GPS.

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AM radio: 535 KHz to 1.7 MHz ( 1 MHz  300 m ~ 328 yards)

Short wave radio: Bands from 5.9 MHz to 26.1 MHz

Citizens band (CB) radio: 26.96 - 27.41 MHz

FM radio: 88 - 108 megahertz ( 98 MHz  10 ft)

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Miscellaneous Consumer Electronics

Garage door openers: 40 MHz

Older Cordless phones: 40-50 MHz, 900 MHz

Baby monitors: 49 MHz

Radio controlled cars and airplanes: 72-75 MHz

Wildlife tracking collars: 215-220 MHzPersonal Computer: ~ 3 GHz

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Primary Amatuer Radio Bands

Amateur radio, or Ham radio, is a hobby enjoyed by about 3 million people throughout the world.

Common Ham bands.

Photo shows a “ham shack” in Kansas.

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Broadcast Television

Television: Broadcast channels 3-83 have frequencies in the range from 45-885 MHz. Satellite TV is currently broadcast in the 12.2-12.7 GHz band in the US and the 10.7-12.75 GHz band in Europe.

Channels 1-6: 45-83 MHzChannels 7-13: 175-211 MHzChannels 14-83: 471-885 MHz

The Panasonic 103 inch plasma television has it's Canadian unveiling in Toronto on Wednesday Dec. 6, 2006. The television is the world's largest plasma device, weighing in at nearly 600 pounds and costing $80,000 CDN (about $69,000 US).

TV Sattelite Bands

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Cell Phones

Regardless of the terminology (Modes) used to characterize cellular technology (PCS, TDMA, CDMA, GSM, GPRS, Cellular, Digital, Analog, etc.), at this time there are only two frequency ranges available to US carriers.

(1) 824 - 896 MHz

(2) 1.85 -1.99 GHz

Hands free set

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Air Traffic Control Radar: 0.96-1.215 GHz

Global Positioning System (GPS): 1.227-1.575 GHz

WiFi: 2.4 GHz for 802.11b and 802.11g. 5 GHz for 802.11a WiFi is a brand name. The underlying technology is known as Wireless Local Area Network (WLAN)

Microwave oven: 2.45 GHz

Bluetooth – Bluetooth is essentially a cable replacement technology, allowing electronic devices such as cell phones, modems and printers to talk to each other wirelessly. It operates in the license-free ISM band at 2.45 GHz. The band is divided into 79 channels, each 1 MHz wide. Channels are changed up to 1600 times per second.

Where does the Bluetooth name come from? It is named after a Danish Viking and King, Harald Blåtand (translated as Bluetooth in English), who lived in the latter part of the 10th century. Harald Blåtand united and controlled Denmark and Norway (hence the inspiration on the name: uniting devices through Bluetooth). He got his name from his very dark hair which was unusual for Vikings, Blåtand means dark complexion. Alternatively, he was thought to like blueberries.

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Radio Astronomy

Most radio astronomy observations are made in the band from about 30 GHz to 1 THz, but there are instruments planned for observations beyond 1 THz.

The Green Bank Telescope (GBT), aka the Great Big Telescope. It is the world’s largest fully steerable radio telescope.

Radio Astronomy Band

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Infrared (IR): from the Latin infra, "below“. The infrared is the region of the spectrum just below the visible red.

IR technologies include: Military target acquisition and tracking Night vision Remote temperature sensing Short-ranged wireless communication (remote controls for TV, stereo, etc,) Spectroscopy Weather forecasting Infrared astronomyAt the atomic level, infrared energy elicits vibrational modes in molecules through a change in the dipole moment, making it a useful frequency range for study of these energy states.

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Far Infrared (FIR): The far infrared is the lower frequency portion of the IR band.

Far-infrared waves are thermal. FIR light penetrates beyond the skin level and is absorbed efficiently by cells below, whereas visible light is mostly bounced off the skin surface. Far-infrared can penetrate up to 1-1/2 inches, exciting the vibrational energy of molecules and resonating with cells. FIR rays can thus raise the core body temperature.

Near infrared waves are not perceived as hot. These shorter wavelengths are the ones used by your TV's remote control.

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The human eye detects electromagnetic radiation in the visible spectrum.

Visible technologies include: Lenses Mirrors Polarizers Beam splitters Prisms Diffraction gratings Photodetectors Lasers Fiber optic cable Light bulbs LEDs

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The near visible spectrum.ultraviolet is absorbed very strongly in the surface layer of the skin by electron transitions. As you go to higher energies, the ionization energies for many molecules are reached and the more dangerous photoionization processes take place. Sunburn is primarily an effect of uv, and ionization produces the risk of skin cancer.

The ozone layer in the upper atmosphere is important for human health because it absorbs most of the harmful ultraviolet radiation from the sun before it reaches the surface. The higher frequencies in the ultraviolet are ionizing radiation and can produce harmful physiological effects ranging from sunburn to skin cancer.

Health concerns for UV exposure are mostly for the range 290-330 nm in wavelength, the range called UVB. According to Scotto, et al, the most effective biological wavelength for producing skin burns is 297 nm. Their research indicates that the biological effects increase logarithmically within the UVB range, with 330 nm being only 0.1% as effective as 297 nm for biological effects. So it is clearly important to control exposure to UVB.

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X-Ray – visible spectrum.Electromagnetic radiation of extremely short wavelength and high frequency.

Wavelengths: 10-8 to 10-11 m (10-0.01 nm)

Frequency: 3x1016 to 3x1019 Hz (30-30,000 PHz)

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Gamma Rays visible spectrum. are high energy waves/particles that can penetrate deeply into solid objects. Their energy is sufficient to cause damage to living cells. Frequency: (1018 – 1021) Hz

Gamma-rays are generated by; Supernova explosions Destruction of atoms Nuclear explosions Decay of radioactive material Neutron stars Pulsars Black holes

Image of entire sky in 100 MeV or greater gamma rays as seen by the EGRET instrument aboard the CGRO spacecraft. Bright spots within the galactic plane are pulsars while those above and below the plane are thought to be quasars.