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Update for 12-11-21 13:15

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Tyler Perkins 2021-11-12 13:15:01 -05:00
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16
tech/Antenna.wiki
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@ -32,7 +32,8 @@ height above ground.
A common feed line in Coax, due to its ease of use. Most for radio
coax has an characteristic impedance of *50 ohms*. TV coax has an impedance of
75 ohms.
75 ohms. In general, larger diamater coax has less loss compared to thinner
cable. Performance of Coax is dependent on the integrity of the outer jacket.
Another common feed line is made of two leads, seperated by plastic. It is
called open wire, ladder line, window line, or twin lead. Becuase there is
@ -96,6 +97,15 @@ physically.
*Ground plane antennas are omnidirectional when mounted parallel to the ground*
== Yagis ==
=== Yagis ===
Yagi antennas are the common house mounted antenna you see for TV.
Yagi antennas are the common house mounted antenna you see for TV. They are
very directional, focusing half of their power 60 degrees, along the axis of
the Yagi. They also can ignore the interference caused by other signals coming
from the sides of the antenna.
=== Dish ===
A Dish in a very focused type of antenna, often used for the 1Ghz+ range of
frequencies. They are directional in the dirction of the dish, and can send and
recieve very focused signals.

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tech/Ham.wiki
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@ -36,3 +36,6 @@ see [[electronics]]
[[Propagation]]
[[Antenna]]
[[SWR]]
== [[Modulation]] ==

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tech/Modulation.wiki Normal file
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@ -0,0 +1,10 @@
= Modulation =
Modulation is the altering of a carrier signal to add infomration. This is done
in everything from raido, to Ethernet.
== Bandwidth ==
Bandwidth is the amount of frequencies that a signal occupies. For example, the
Human voice can make frequencies from 300Hz to 3000Hz, therefore having a
bandwidth of 3000 - 300 = 2700Hz.

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tech/SWR.wiki
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@ -24,3 +24,12 @@ If you expereince SWR, check
* Antenna length vs frequency
* Faulty feed lines/feed line connectors
* Erratic SWR means loose connections in feed line
== Meters ==
An SWR meter allows you to measure the power flowing to and from the antenna,
therefore calculating the amount of SWR. Another type of SWR meter is a
directional Wattmeter, determining the amount of power in each direction.
Antenna tuners exist, which alter the Impedance of the feed line to match that
of the antenna, so make the SWR 1:1. This is either manual or automatic.