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Predictions indicate that the three largest metro areas along the Wasatch Front (Ogden, to the north, Provo, to the south, and the Salt Lake area) will get approximately equal signals. When arranging antenna in somewhat overlapping patterns in this way, it is imperative that attention be paid to phasing the transmit signals: If two adjacent antennas are about 180 degrees out of phase with each other, deep nulls can occur in the overlap area.
Calculations show that the the overlap areas occur in areas that,
owing
to geography, have very low population (i.e. the traverse mountain
range
to the south, and border of Salt Lake and Davis counties to the north,
where the lake and the mountain nearly narrow, and there is a heavily
industrialized
zone.) Also, simple field-strength measurements can be used to
verify
proper phasing of the antenna. These calculations have been borne
out by some actual field measurements (documented near the bottom of
the
Receiving
the WB7FID Repeater at Your QTH page) in that signals are
actually
stronger
in the overlap areas than expected. See also the Predicted
coverage of the WB7FID ATV repeater page for coverage maps
and related information.
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The intent was to divide power equally amongst the three
antennas:
To accomplish that, Dale, WB7FID, built the pictured power
divider.
This is a fairly simple (but carefully crafted) coaxial device that
transforms
50 ohms to 16.66 ohms with very good return loss and very low insertion
loss (above that minimum 4.8 db intrinsic to a 3-way divider, of
course...)
What's inside this device? Just a piece of tubing - with its O.D.
chosen such that, along with the inside dimensions of the square
aluminum
tubing, the size ratio yields a 33 ohm piece of transmission line that
is 1/4 wave long.
Keep watching this page, as it will be updated as time goes
on...
Do you have any questions/comments about what you have just read? If
so,
please
email me and
make an ask of yourself...
Return to the New WB7FID ATV Repeater Page...