On Thu, 3 Jan 2008, chris Inos wrote:
> I used my IC-28H..(mobile) .which has "led bars" on rx signal
> strength. I drove around the island and map out receptions on
> strategic points. Clients are satisfied that a 15-watts tx at
> repeater site covered the whole island (32 square miles). Repeater
> located at center (highest point) of the island about 1700 ft. above
> sea level...coverage of 20+miles easy. All system powered by solar
> power.
Two approaches for this situation: gain and angle, and 1/4 wave ground
plane.
Without any antenna gain, your pattern should be relatively close to an
ideal ground plane, which will give you coverage from the horizon to
almost 85 degrees vertical. Unfortunately, having no antenna gain, your
ERP will equal your transmitter power, but since you're located so high
up, and at the point of being virtually line of sight to everywhere,
this is not an issue.
The more expensive route would be to get an antenna like a Super
StationMaster, but spec'd with serious downtilt (> 10 degrees), so that
the main lobe covers only the island itself. This would allow you to
save on transmitter power, at the cost of an antenna. In your location,
out in the middle of the Pacific, antenna shipping costs are not
trivial, and power isn't much of a luxury either. Not to mention the
elements can be brutal as well.
18 watt transmitter, 1.8 dBi of transmit and recieve gain, pathloss is
about 110 dB at 148MHz.
--
Kris Kirby, KE4AHR <[EMAIL PROTECTED]>
But remember, with no superpowers comes no responsibility.
--rly
