Received-SPF: neutral (google.com: 193.82.116.20 is neither permitted nor denied by best guess record for domain of owner-rsgb_lf_group@blacksheep.org)
From: "james moritz" <j.r.moritz@herts.ac.uk>
To: <rsgb_lf_group@blacksheep.org>
Date: Mon, 9 Oct 2006 14:46:46 +0100
Message-ID: <000801c6eba9$5caeae70$e6a4c593@RD40002>
MIME-Version: 1.0
Importance: Normal
In-Reply-To: <008b01c6eb0c$0ead2140$21c428c3@captbrian>
Subject: LF: Re: erp ierp VY1JA
Content-Type: text/plain;
	charset="us-ascii"
Content-Transfer-Encoding: quoted-printable
Sender: owner-rsgb_lf_group@blacksheep.org
Precedence: bulk
Reply-To: rsgb_lf_group@blacksheep.org
Status: O

Dear Bryan, LF Group,

ERP is defined by the field strength at a point distant from the TX. =
Field
strength is a measure of how much signal is present at a particular =
point in
space. Of course, if you place a receiving antenna at that point, the =
signal
level at the antenna terminals will be reduced if its polarisation does =
not
correspond to that of the signal. But the field strength itself does not
depend on the receiving antenna, or indeed the presence of any antenna =
at
all.

In practice, to measure field strength, you usually have to use some =
kind of
calibrated antenna to convert the radio wave into an electrical signal, =
with
a known relationship between field strength and antenna output signal =
level.
It is up to you to ensure that any effect of mismatched polarisation (or
directional pattern, mismatch or any other kind of gain or loss)is taken
into account.

Cheers, Jim Moritz
73 de M0BMU

-----Original Message-----
From: owner-rsgb_lf_group@blacksheep.org
[mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of captbrian
Sent: 08 October 2006 20:01
To: rsgb_lf_group@blacksheep.org
Subject: Re: LF: Re: erp ierp VY1JA

Well I always thought  there was a large loss depending on the extent to
which polarisation differed between emitter and recvr.?