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The reflected power is the amount of power (in watts) that is reflected back from the antenna (in the form of
standing waves). This power is reflected back to the transmitter as a result of antenna
mismatch. The lower the reflected power, the better; this power eventually becomes
dissipated by the output section of the transmitter, and it could damage it. The reflected
power can be calculated with a reflection meter.
Standing waves are waves of RF signal that are reflected back to the transmitter as a result of an impedance
mismatch. The reflected power is a measurement of the amount of power that is wasted in standing waves.
Likewise, the VSWR is the ratio of standing waves in a radio transmitting system.
The VSWR rating represents the voltage standing wave ratio in a system. The ratio
represented is actually either the ratio of the maximum voltage to the minimum voltage or
the maximum current to the minimum current. For most people, this isn't important. What is
important is that you need to keep the ratio as low (close to 1:1) as possible. A VSWR
(usually known as SWR) of more than 3:1 is too high and you either need an antenna coupler or (if you don't have
one) you need to trim your antenna to the correct (resonant) length. The SWR is typically measured on an SWR
meter, although this function is sometimes built into transceivers and antenna tuners.
The field strength is the measure of a radio signal as it is being transmitted from the antenna. The field
strength is usually determined in microvolts per meter away from the antenna. To measure this voltage, you must
use a field-strength meter.
Reflected Power is the
amount of power
reflected back from
the antenna.
REFLECTED POWER
STANDING WAVES
VSWR should
always be kept as
low as possible.
VSWR
FIELD STRENGTH
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