| |
HB9ABX > ANTENNEN 23.06.20 18:57l 123 Lines 6061 Bytes #999 (999) @ WW
BID : N6UDB0FHN051
Read: GAST
Subj: Antennas and Physics
Path: DB0FFL<DB0FHN
Sent: 200623/1757z @:DB0FHN.#BAY.DEU.EU [JN59NK Nuernberg] obcm1.07b12 LT:999
From: HB9ABX @ DB0FHN.#BAY.DEU.EU (Felix)
To: ANTENNEN @ WW
Reply-To: HB9ABX @ HB9EAS.CHE.EU
X-Info: Sent with login password
Antennas and Physics
Antennas are structures, which convert electrical oscillations of a line into
radio waves in space, and respectively convert radio waves into electrical
oscillations in a line.
In classical theory, an antenna is treated as a device, where an oscillating
current flowing in a conductor produces a (electro) magnetic field (EM field),
which converges into E and H field, to an electromagnetic wave (EM wave)
travelling in space.
The exact cause of the EM wave is said to be acceleration of electric charge.
( See http://www.antenna-theory.com/basics/whyantennasradiate.php
and http://personal.ee.surrey.ac.uk/Personal/D.Jefferies/radimp.html
and http://farside.ph.utexas.edu/teaching/em/lectures/node94.html )
This theory, concentrated on the “current in the wireö, was leading to the
development of the traditional antennas as: dipols, yagis, LPSs, verticals,
loops and so on.
This theory is correct, however it does not represent the full truth.
Only one half of the physics is considered here, because EM waves are not only
generated by time varying magnetic fields, but also by dynamically varying
electric fields.
This fact became clear to me by studying the Maxwell equations, and by thoughts
gained through quantum physics, especially through the behaving and the
properties of photons.
( http://en.wikipedia.org/wiki/Maxwell's_equations
http://en.wikipedia.org/wiki/Photon )
In the Maxwell equations you find the Gauss’ law, the Maxwell-Faradays law of
induction, and the expanded Ampère’s circuital law. They describe the dynamic
interaction of the curly electric and magnetic field, and the current.
Technical handbooks treat EM waves throughout as waves, generated by
oscillating current in a conductor, where the radiation begins. Accordingly
the formulas are established.
The frequently used antenna simulation program NEC (EZNEC) and its family does
not (yet) allow to define and simulate of my new antenna construction.
As a consequence, special äantenna rules“ were createt, based on this one-side
view.
As an example, good antenna texts lists the following "golden rules" for
antenna design:
1. Much wire in the air will bring the best results
2. As high as possible (antenna at ground level is bad)
3. Current radiates (ARRL Handbook: current produces the radiated signal)
Furthermore, most antenna books write, that antennas with the higher radiation
resistance radiate more, and that short antennas generally have a very low
efficiency.
All these above rules are based on the experience gained during many years of
work with traditional wire antennas.
Now I don’t want to say, that these rules are wrong, but I have to limit
applicability of them: They are only valid for antennas based on the physical
law of wave generation by oscillating currents in a conductor.
Traditional antennas are based on this principle.
However, when the RF current flows though an area, then new properties appears.
E.g. with short radiators a much higher radiation resistance is obtained, than
the formulas states, that the formulas based on the dipoles!
An area forms a capacity, which produces a strong E field.
By build an antenna, which bases on the open dynamic E field, then the old
formulas does not apply, as here other formulas apply for this case.
The intention for my new antenna design was, to produce a maximum dynamic E
field in the space around the antenna.
During the last years I built such antennas and conducted many field tests,
comparing this antenna with traditional wire antennas. The result was, that an
antenna with 150cm radiator length (= 5 feet) at a wavelength of 40m produced
constantly the same signal strength, and many times a stronger signal at the
remote station, by comparing with dipols, verticals, G5RV, FD3, and longwires.
The transmit power and the location were identical, and during the qso many
switchovers between the test antenna, and comparing wire antenna were made.
The hight above ground of the base of the new antenna was only 50cm to 150cm,
while the comparing antenna was in its original hight!
Hundreds of tests were made from 10m to 160m wavelength, and always the same
result was obtained. The length of the radiator on 160m was just 3m!
I published many of these tests in the internet under “New HF Antennaö.
The following criterias apply for the "New HF Antenna" = Roomcap
- areas (planes) are used, which form in the space a capacity, in which the E
field is produced.
- these areas have to be arranged in a special manner, open into space (a
capacitor with two directly opposed plates produces practically no radiation).
- the feedline may not be part of the antenna. The line is not allowed to
radiate.
- feeding of the antenna has to be floating, without reference to ground.
- the impedance has to be adjusted such, that the SWR is below 1.5
- the dimension of the areas has to be small in relation to the wavelength.
(Length of the radiator < 7% of the wavelength, otherwise the phase difference
of the E field is reducing the radiation efficiency).
In my realisation, feeding is made by the "varylink". This is part of the
antenna structure and permits to obtain a SWR below 1.1 on each band.
This has the advantage, that the antenna does not require an antenna tuner.
Other realisations:
Others have also developed antenna types, which are using the principle of E
field wave generation. E.g. Isotron, Microvert, EH-Antenna (Crossfield antenna
CFA) and similars.
All these realisations do not fulfill all criterias listed above, and therefore
their efficiency is 8 db to 18 db less than the “New HF Antennaö.
Future:
Development of additional versions of this antenna continues.
The significance of this antenna will be important, due to many restrictions in
available space, and regulations to errect traditional antennas with their
large physical dimensions.
Felix Meyer, HB9ABX
Lese vorherige Mail | Lese naechste Mail
| |
