If you flip the beam vertical, what happens to the pattern compared to
running it horizontal. How does the pattern change as its lowered closer to
----- Original Message -----
From: "Pete Smith" <email@example.com>
To: "Stephen Reichlyn" <Stephen.Reichlyn@ryansci.com>;
Sent: Tuesday, January 18, 2005 10:10 AM
Subject: Re: [TowerTalk] horizontally polarized antennas and salt water
> At 01:53 PM 1/17/2005, Stephen Reichlyn wrote:
> >Gentlemen and Ladies of Towertalk:
> >Anecdotal comments about antennas and their performance by the sea are
> >many and sundry. I wonder if
> >those who have experience with this phenomena can comments on the
> >following points:
> >We have all read that vertical antennas work especially well on (or near)
> >the beach. I have first hand experience
> >with this and certainly agree that this is the case. I often wondered
> >whether radials (even simple 2 wire systems)
> >are really needed next to salt water.
> >1.The ultimate question is 'what effect does the salt water have on
> >horizontally polarized HF antennas, if qny'?
> >2. Do you think that tidal changes (for instance +/- 6 feet) in the near
> >field have an effect on angle of radiation
> >of horizontally polarized antennas, such as yagis.
> >3. How far away from the ocean (in miles) do you think the near field
> >water effect disappears?
> >4. Or do you think that salt water near field has NO effect on
> >horizontally polarized antennas?
> It does, but not a bunch.
> I quickly modeled a 40m yagi at 104 feet over average ground versus salt
> water. Forward gain went from 11.86 dBi (avg) at 18 degrees to 12.45 dBi
> (salt). Takeoff angle, interestingly, went up one degree for the better
> ground plane. Moving the antenna down 6 feet over salt water moved the
> takeoff angle up 1 more degree, from 19 to 20 degrees.
> 73, Pete
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See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
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