Glossary of Terms found on the pages of
VK3BJM.
|
Term |
Definition |
|
AEP |
Aircraft Enhanced Propagation. VHF, UHF, and SHF Radio signals can be “scattered” over the horizon
by aircraft. There is still debate as
to whether the scattering is caused by the metal body of the aircraft, or by
the exhaust trail from the aircraft engines.
Theoretically AEP can be used to provide paths up to 1,000km. |
|
Aurora |
VHF
and UHF signals can be “bounced” off the Aurora that forms at the North and
South Poles after intense solar flare activity. The sound of signals that have been propagated via Aurora is
very distinctive – the audio becomes harsh and raspy, and newcomers to the
mode can find the resultant signal difficult to understand. |
|
DX |
Abbreviation
for “Long Distance”. |
|
EME |
Earth-Moon-Earth.
VHF, UHF and Microwave radio signals can be “reflected” off the moon
back to the earth, enabling contacts to be made over non line of sight
paths. EME permits contacts between
Australia and the Americas, Europe and Africa. EME is not easy – most amateurs consider success in this
propagation mode the pinnacle of achievement. |
|
IF |
Intermediate Frequency.
A frequency found between stages in radio equipment. |
|
Grid “Squares” |
More
formally known as Maidenhead Grid Locators.
A system to provide location information, but with a lesser degree of
accuracy than that achieved by using Latitude and Longitude. The location information is imparted by
way of an alphanumeric code, for example QF22. The four character covers an area equal to that of one degree
of latitude and two degrees of longitude.
Greater accuracy is provided by a further two alpha characters tacked
on the end, to give a six character code; eg, QF22es. The term Grid “Square” is a source of mild
annoyance to some, as the locator shape is not a true square, but a
quadrangle! More information on Grid
“Squares” can be found on the Wireless
Institute of Australia website. |
|
MS |
Meteor Scatter. VHF Radio
signals can be “scattered” over the horizon by the trails of meteors burning
up in the Earths’ atmosphere. MS can
be used to provide paths between 500 and 2,000km. |
|
Propagation |
Mechanisms
that aid the transport of radio signals from one point to another. |
|
RF |
Radio Frequency.
Frequencies between Audio and Light. |
|
SHF |
Super
High Frequency. Frequencies nominally
between 3,000MHz and 30,000MHz. |
|
TEP |
Trans Equatorial Propagation. |
|
Tropo Scatter |
Tropospheric
Scatter. Radio signals can be
“scattered” over the horizon by dust, particles, cloud droplets, and
small-scale irregularities in the radio refractive index of the
troposphere. Tropo Scatter can be
used to provide paths up to 1,000km. |
|
Tropo “Ducting” |
Tropospheric
“Ducting”. Due to some remarkable
recent work by Andrew Martin VK3KAQ and others, the term “ducting” is
becoming an anachronism. It was once
thought that layers of warm and cool air formed pipes or “ducts” which in
radio signals became trapped, where they’d travel long distances before
emerging at the far end. Andrew’s
work, much of which has been presented at the 2004 and 2005 GippsTech forums,
suggests that something more like a rough-surface mirror forms at the
junction between the warm and cool air layers. This bends the signal – perhaps several times – to return it to
earth at the distant end. Whatever
you call it, this propagation mode can provide paths up to 4,500km. |
|
TVI |
Television Interference. Can be caused by a number of factors, chiefly due to poor TV
receiver design. |
|
UHF |
Ultra High Frequency.
Frequencies nominally between 300MHz and 3000MHz. |
|
VHF |
Very High Frequency.
Frequencies nominally between 30MHz and 300MHz. |
|
Yagi |
A
directional antenna consisting of a number of “elements” mounted parallel to
each other and spread along a “boom” – see photographic examples in the photo
galleries. Sometimes referred to by
more energetic people as “Yagi-Uda” antenna, and named after the Japanese
designers Hidetsugu Yagi and Shintaro Uda. |
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Updated
5/9/2005