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EH
Antenna … it is as plain as the nose on your face !!! This
is what a specialized magazine wrote … “…
a concept that risks to change our convictions … “ The “EH Antenna” topic started off in
2001 and still to-day is very much argued and discussed between those who
believe and those who simply don’t. The fact remains that whoever has given the
antenna a try is nothing but flabbergasted. An Eh antenna allows you to verify out of
imagination characteristics if compared with a classical trapped (loaded)
antenna. As a matter of fact, the size of the
antenna, the feature that surprises most, is one of the minor aspects. The most important features are the very low
noise (high S/N ratio); the wide bandwidth (low Q factor); the elevated
efficiency (more than 95%) and the excellent characteristics of an antenna
per a DX use. The aforementioned features are completely
in contrast with an antenna of similar dimensions that performs according to
the classical concepts (Resonance). An EH antenna performs by transforming the
energy from the TX into electromagnetic wave (and vice versa) like other
antennas, with the difference that such transformation occurs at the EH
antenna in the near field. But: how can you obtain radiation at the
near field, when any other antenna (that is not an EH antenna) allows this
transformation of energy (from electric and magnetic field into
electromagnetic field) to occur at the far field? It is so simple to seem impossible and this
is the most difficult concept to accept, especially for the experts. To synthesize the explanation as much as
possible, you could say that the EH antenna works (…. Well) because it
fully satisfies those conditions dictated by the theory of Poynting within
the area immediately next to the antenna itself. To give a more detailed explanation, you
could say that when you supply energy (RF) to a classical antenna, an E
field (Electric field) and an H field (Magnetic field) are developed. At an
approximate distance of 0,3 lambda from the antenna (hence, at a certain
distance from the antenna) conditions achieved will allow the E and the H
fields , still separate, to join each other and originate the
electromagnetic field (Radiation). If the antenna is fed with a proper circuit
(EH Network), which allows to obtain the necessary conditions so that the
two fields (Electric & Magnetic) are in the proper conditions of phase,
amplitude, ratio etc., (i.e. they satisfy all conditions dictated by the
theory of Poynting in the area next to the antenna), you will have radiation
direct at the antenna. Proof of this, once you obtain the
performance of an antenna according to the EH Mode, you achieve high values
of radiation resistance also for very small antennas. Can you imagine anything more simple than
that? Why is it that we realise this only now? Personally, we deem the reason to be very
simple, i.e. others have just not wanted (or have not known) to think of an
antenna in a different prospect from a classical antenna. It really is as plain as the nose on your
face !!! Although, we well know that everything appears easier and trivial
once you learn about it. REFERENCES: Website of Robert Ted Hart, inventor of the
EH Antenna concept and owner of the relative patents. www.eh-antenna.com. Arno
Elettronica (Licensee in Europe).
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EH nude ...
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