From: WarmSpgs@aol.com
Message-ID: <16d21cb2.24c5e57b@aol.com>
Date: Tue, 20 Jul 1999 10:45:15 EDT
Subject: Re: LF: ERP and all that jazz
To: rsgb_lf_group@blacksheep.org
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In a message dated 99-07-19 09:08:45 EDT, PA0SE writes:

<< Maybe it is better to avoid using e.r.p. at all. 
 What you could use is e.i.r.p. . . . . >>

Yes, I believe this is far better.  EIRP is already the equivalent of the 
"eurowatt."  It is the measure used in nearly all commercial situations now.  
If you know EIRP in the direction of interest, it is not necessary to know 
anything about the transmitting antenna (except its location, of course) in 
order to predict field strengths along a given path.  Or, conversely, if 
field strength can be measured, EIRP can be determined without reference to 
antenna type.  Hence, EIRP is easier to deal with and can be applied almost 
universally.

In the U.S., because the FCC already specifies EIRP for the radiated power of 
most services, our LF ham bands are likely to be limited to 200 W TPO and a 
maximum of 2 W EIRP, assuming something similar to the ARRL petition is 
adopted.  This means that (if we have reason to suspect our antennae are 
anywhere near one percent efficient) we will have to find the direction of 
strongest radiation from the antenna, and determine EIRP by measurement in 
that direction.  However, it will be far more practical to do this than to 
make guesses about ground system losses and relative gain versus a dipole, 
etc.

Although amateurs have tended to use the term ERP rather loosely, and I'm not 
at all sure what each administration actually implemented, didn't the CEPT 
recommend the power limit on 136 kHz in terms of EIRP?

73,
John  KD4IDY