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Update for 12-11-21 12:45

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Tyler Perkins 2021-11-12 12:45:01 -05:00
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29
tech/Impedance.wiki
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@ -8,3 +8,32 @@ causing voltage to get out of sync.
This getting out of sync is called reactance. The total reactance is called
Impedance. Impedance is measured in Ohms, shown as Z
== Inductors ==
An inductor creates a magnetic field, which when the direction of the voltage
switches, the field resists this change, creating a phase shift. This causes
some resistance, which is why impedance is measured in Ohms. The phase shift,
and therefore the resistance, is directly based on the frequency of the AC
signal. The relationship is shown below
X,,l,, = 2(pi)fL
Where X,,l,, is the inductive reactance (in Ohms),
f is AC signal frequency (in hz),
and L is the inductance (in henery)
*Inductors always make voltage lead current*
== Capacitors ==
A capacitor creates an electrostatic field, which swaps which plate of the
capacitor each charge forms on, when the direction changes. As a result, this
creates some resistance, measured in Ohms. The phase shift (in current) is
based on the frequency of the AC signal. The relationship is shown below
X,,c,, = 1 / 2(pi)fC
Where X,,c,, is the capactive reactance (in Ohms),
f is the AC signal frequency (in hz),
and C is the capacitance (in f)

8
tech/SWR.wiki
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@ -1,8 +1,14 @@
= SWR =
Standing Wave Radio (SWR) is a phenomenon where power sent down a feed line is
reflected back by the antenna.
reflected back by the antenna. Due to this, a standing wave is formed in the
feed line.
This only occours when the impedance of the antenna and the feed line do not
match. This is often caused by having the incorrect sized antenna for the
signal.
SWR is the same as the ratio of antenna-to-feed or feedline-to-antenna
impedances, whichever is greater than 1. No reflected power is a ratio of 1,
and means that there is no interference pattern. Because [[Impedance]] changes with
frequency, the SWR also changes with frequency.