From: "Richard Fry"
Date: 11/9/04 6:29 AM Pacific Standard Time
Message-id:

Well, a 6 dB boost would double your range, IF you aren't
hitting the limits imposed by your radio horizon.
_____________

Clarification: the coverage AREA doubles for the above situation, but the
"range," or distance from the transmit antenna to a given field strength
value increases only by about 40%.

Here are the numbers, using the FCC's F50,50 curves for UHF NTSC TV
propagation.

50W ERP from 100 feet above average terrain:

60dBuV/m at 2.99 miles
Coverage area within the 60dBuV/m contour = 28 sq miles

200W ERP from 100 feet above average terrain (a 6dB ERP increase from the
above example):

66dBuV/m at 2.99 miles
60dBuV/m at 4.2 miles
Coverage area within the 60dBuV/m contour = 55.4 sq miles

The radio horizon for these examples is located about 14 miles from the
antenna site (at a 0.15 degree depression angle).

RF

Visit http://rfry.org for FM transmission system papers.

I stand by my statement, " 6dB doubles your range". Rather than going to an
obscure site and referencing something about some TV coverage - just run the
numbers. We are not talking about broadcast to consumer TV sets here. Anyone
who has done path analysis knows that 6dB doubles the range. Check into it -
you might learn. On second thought here is the equation -
Loss (dB) = 36.6 + 20 log F (MHz) + 20 log D (statue miles). And, again, as
first stated, " within the limits of the radio horizon". Off course, space
shuttle mobil and EME folks don't worry about the horizon.

KF6HHS
Retired, now life moves at my pace.
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