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KGRU 96.1 Specifications
KGRU LP is licensed for 100W ERP.
ERP means Effective Radiated Power.
We have a circular polarized antenna with a right hand polarization.
This means that our signal is transmitted in the vertical plane,
horizontal plane and everthing in between. The antenna is fed
with 100 feet of 1/2 inch superflex coax with low loss N type
connectors on each end.
The FCC specifies 100W transmitted at the antenna in one plane.
In other words, since we are dividing our signal between horizontal
and vertical we set our transmitter to about 24O Watts output.
100W vertical, 100W horizontal and some additional power
that is absorbed as feedline and feedline connector loss.
A circular polarized signal is great at minimuzing fading due
to vertical and horizontal polarity changes. For example
if you get a signal bounce off of the barn (FM = line of sight
propagation) in the field next to you. That changes the signal
from horizontal polarized to vertical and if your receive antenna
is in the horizontal plane, that would degrade your received
signal tremendously. However, with a signal that is basically
horizontal, vertical and everything between, the received signal
will always be optimized to match your receive antenna plane.
We are allowed an antenna height of 30 meters HAAT, that means
Height Above Average Terrain averaged out for 10 miles. At this
time we are at a -79 meters HAAT due to being on the Kittitas
Valley Floor.
The actual height above ground level for our antenna is 19 meters
or about 62 feet. As you can see that leaves us with quite a
bit of room to work with in the future for station improvement
and it will be one of our goals to erect a much taller tower
structure.
Again, FM = line of sight reception, so the higher we go, the
farther we are
heard. This also works on the receive end, the higher you get
your receive
antenna the farther you can hear.
Our transmitter is a RFcast MT300 300 W solid state
stereo transmitter.
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