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LF: RE: The CFA Antenna (again...)

To: [email protected]
Subject: LF: RE: The CFA Antenna (again...)
From: "Andrew Talbot" <[email protected]>
Date: 2 Aug 2001 08:32:44 +0100
Reply-to: [email protected]
Sender: <[email protected]>
Yes.  That is exactly what Maxwell stated and Hertz demonstrated 10 years
later (I've just been re-reading a book on basic Electromagnetism).

One field is generated from the other as soon as its value changes in time.

Anyone who claims to be generating them separately probably only has a
partial understanding of the whole process !  The realtive levels of E and H
close to the antenna can vary widely depending on antenna topology, these
are the near fields talked about a lot here recently, but in the far field
both have to exist together, qith E and H related by 120.pi,  the impedance
of free space.

As far as I can make out, all these wonder antennas just consist of a short
E field element, with its resultant loss and high capacitance, both phased
and resonated with a Loop like element with its high loss and inductive
reactance.  The two reactances are made to cancel, leaving a purely
resistive element to be matched over a narrow bandwidth.  If the bandwith is
not narrow then the antenna is lossy.  QED.

Andy  G4JNT


-----Original Message-----
From: Alberto di Bene [mailto:[email protected]]
Sent: 2001-08-01 16:17
To: LF Mailing List
Subject: LF: The CFA Antenna (again...)


It seems that the CFA Antenna now has a new incarnation,
under the name 'EH Antenna'.

Look here :  http://www.netcommander.com/home/w5qjr-/index.htm

Or, for ham-related stuff, here : http://www.qsl.net/w0kph/

What makes me perplex, is the citation of 'independent E and H fields'.
Unless I completely misunderstood what Maxwell said, the only case
when an E field can exist without a corresponding H field (and viceversa),
is when they are stationary (in time) fields.  Or am I wrong ?

73  Alberto  I2PHD




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