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A Brief Look at the Electromagnetic Spectrum


A Brief Look at the Electromagnetic Spectrum Disclaimer This PowerPoint presentation was designed as one of a series of lunch seminars for employees at Virginia ... – PowerPoint PPT presentation

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Title: A Brief Look at the Electromagnetic Spectrum

A Brief Look at the Electromagnetic Spectrum
Disclaimer 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
A Brief Look at the Electromagnetic Spectrum
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
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 30300 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)
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.
Radio 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)
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
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
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
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
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.
Traffic Radar Bands
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Microwave and mm-Wave Band Designations
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 worlds largest fully
steerable radio telescope.
Radio Astronomy Band
Atmospheric Absorption
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
astronomy At 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.
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
There is an entire industry of health products
designed to operate in the FIR.
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The human eye detects electromagnetic radiation
in the visible spectrum.
Visible technologies include Lenses Mirrors Po
larizers Beam splitters Prisms Diffraction
gratings Photodetectors Lasers Fiber optic
cable Light bulbs LEDs
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The near 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.
X-Ray 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 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.
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