EZNEC shows the gain increasing about half a dB from 69 to 79 feet. However,
it also shows the gain dropping back .5dB at 110 feet, where the angle is
more desirable. I suspect these minor gain differences are due to
inconsequential changes in the forward lobe.
> -----Original Message-----
> From: Jim Lux [mailto:jimlux@earthlink.net]
> Sent: Saturday, October 16, 2004 11:31 AM
> To: W3YY; TowerTalk List
> Subject: Re: [TowerTalk] Tower height increments
>
>
> Of potentially more interest might be what happens to the
> gain at say 5 or 10 degrees elevation angle, rather than
> where the main lobe happens to
> point. In this particular case, with "average ground" it's
> about 0.5 dB
> difference at 10 degrees, and about the same at 5 degrees.
> Unfortunately HFTA doesn't plot below 0dBi (even though
> that's barely 1.5 S units below the peak), and the peak
> elevation angle for propagation on 40 is only 3 degrees above
> the horizon (I used Ohio to EU, because I don't have all the
> files uncompressed)
>
> ----- Original Message -----
> From: "W3YY" <w3yy@cox.net>
> To: "TowerTalk List" <towertalk@contesting.com>
> Sent: Saturday, October 16, 2004 12:40 AM
> Subject: Re: [TowerTalk] Tower height increments
>
>
> > Warren -
> >
> > Using HFTA and modeling a 2-el 40-m beam over flat ground, the lobe
> > moves from an elevation angle of about 29 deg at 69ft to 25 deg at
> > 79ft. It's probably not worth going through a lot of extra work to
> > obtain this
> change.
> >
> > 73, Bob - W3YY
>
>
>
>
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