From: "Mike Dennison" <mike.dennison@rsgb.org.uk>
To: rsgb_lf_group@blacksheep.org
Date: Thu, 4 Jan 2001 17:27:47 -0000
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII; format=flowed
Content-Transfer-Encoding: 8bit
Subject: Re: LF: Large and small antennas
Message-ID: <3A54B293.13773.446063@localhost>
In-reply-to: <IaB0tSA2W3U6EwAx@jalowe.demon.co.uk>
References: <3A531C89.2032.BB2276@localhost>
Precedence: bulk
Reply-To: rsgb_lf_group@blacksheep.org
Sender: <majordom@post.thorcom.com>

G3XZX wrote:
> Am I correct in thinking that because a full-sized dipole or other
> very large antenna, at a sufficient height, will have a different
> radiation pattern from a short monopole, 1 watt ERP from each antenna
> judged by field strength measurement at the same location will give
> rise to different field strengths at various other distances because
> the sum of sky and ground wave effects changes differently with
> distance for the two antenna types?

Well, here we get into the very muddy waters of just how you 
measure ERP - seemingly a very imprecise science. Also the far 
more interesting area of matching the antenna to the propagation 
medium (sometimes referred to as ionospheric matching). An 
example of this is the idea that a "useless" horizontal antenna - or 
the horizontal part of an L - can in some cases give an improvement 
on the pure vertical because of the way the signal is presented to 
the ionosphere. And this is another area where the unreliability of 
the technique makes it a taboo area for the commercials but a 
potential source of gold for us.

Isn't radio fascinating?


Mike, G3XDV (IO91VT)
http://www.lf.thersgb.net