Topband: Low band antenna project questions
jim at audiosystemsgroup.com
Mon Mar 7 18:11:58 EST 2016
On Mon,3/7/2016 2:37 PM, Bill N6MW wrote:
> The V7 version with 2 drooping T wires and 2 elevated radials for each
> band was just okay on 160 but good on 80,
Drooping Tee wires will reduce the effective height of the antenna by a
significant fraction of their droop.
> probably limited by trees proximity and restricted geometry, although
> some might claim enhanced by being on a beach with adjacent ocean.
Verticals near the beach need an effective radial/counterpoise. Only if
the feed is directly over water and the coax return makes very good
contact with it will sea water serve as a counterpoise. The vertical
pattern of any antenna is produced by the reinforcement of the direct
wave by the first reflection from the earth. That reflection is MUCH
stronger, and is strong at a lower angle, if the "earth" at the point of
reflection is sea water. Sea water will NOT improve signal strength in
directions where the first reflection is over land.
73, Jim K9YC
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