| |
HB9ABX > ANTENNA 15.06.20 17:49l 144 Lines 6375 Bytes #999 (999) @ WW
BID : F6UDB0FHN08A
Read: GUEST
Subj: EH-ANTENNA : Conclusions
Path: IW8PGT<IZ3LSV<DB0ERF<DB0RES<DB0OVN<DB0GOS<DB0RBS<DB0FHN
Sent: 200615/1532z @:DB0FHN.#BAY.DEU.EU [JN59NK Nuernberg] obcm1.07b12 LT:999
From: HB9ABX @ DB0FHN.#BAY.DEU.EU (Felix)
To: ANTENNA @ WW
Reply-To: HB9ABX @ HB9EAS.CHE.EU
X-Info: Sent with login password
EH-ANTENNA : Conclusions
I was investigating this special EH-Antenna by collecting informatfrom HAMs who
commented the antenna , based on their own experience.
In the following, I provide the obtained comments, and at the end I will add my
own conclusions, based on detailed study of the theory.
I want to thank all HAMs who contributed with their comments:
DL2SSR, DJ2ZS, DJ3JV, HB9EBV, WB2WIK
---------------------------------------------------------------
A radio friend who obtained the 40 m version EH-Antenna came to the following
result: A DV 27 from CB radio is performing much better.
The difference between them are worlds ...
----------------------------------------------------------------------------
It's not a joke: This mistery is is found since about 1990 in the radio world
of curious antennas, either as cross-field or EH-Antenna. But there is a
tremendous difference between reality and theory, as the theory of this concept
is beautiful, beautifully wrong :-)
The fields cannot be "crossed" this way. This antenna consists of two small
antennas, of which one produces a strong E field, and the other a strong H
field in the near field. Both fields radiate and combine to an electromagnetic
far field.
That's all.
The efficiency is that of a small antenna, that means: nothing special.
But "everything radiates" and the logarithmic scale in the form of db's make
the difference smaller.
------------------------------------------------------------------------------------------------
An OM wrote to me, that he performed with another HAM a comparitive
test on 40m between a ground plane and an EH-Antenna ( EH installed
much higher than the grond plane antenna) over a distance of 10 km.
The result: S9 for ground plane, S4-5 for EH-antenna.
He named therefore the EH-antenna "an expensive dummy load".
> The performance of the EH should equal a conventional antenna.
Yes, I was reading that, but the EH surely is not a "wonder antenna".
I would be very interested in obtaining experiences of other HAMs
if you obtain such information.
------------------------------------------------------------------------------------
I ordered an EH-antenna from WIMO and installed it in a good location.
Comparing the antenna against a dipole at the same location, the EH generally
gave 5 to 6 S-points less in transmission as well as in receiption.
After intensive tests I decided to pack the antenna nicely into its box and to
offer it for sale ...
----------------------------------------------------------------------------------------------
Tests during 6 weeks in 296 QSOs in SSB and CW on 20m, comparing the
performance with a 6 band GP (6BTV) over short and long distances showed the
following:
Generally 20 db less signal for the EH-antenna.
----------------------------------------------------------------------------------------
Comment by HB9ABX :
Furthermore, I studied the theory of the EH-Antenna as presented by the
inventor Ted Hart, W5QJR.
( http://www.eh-antenna.com/ )
Here I discovered, that all this theory is only based on a wishful thinking.
All this theory is pure imagination without any scientific background or
technical know how .
Complete nonsense.
(Update 8.July 05: Here I refer to the document "EH Antenna -
Definition, Ted Hart, 10-28-02)
The antenna is just an open resonant circuit, formed by the capacity of the two
"cans" and the coil between them, with a matching section to adapt the feeding
impedance.
At the same time, the feeding coax becomes an active radiator which makes, that
this combination is radiating more or less ...
The coax also radiates when a current balun is inserted, as the electric field
is very high and couples directly to the 1/2 wave cable.
20 dB attenuation corresponds to a power relation of 100:1, or 99% power
loss.
30 dB ( 5 S points) correspond to a power relation of 1000:1 what the tests
showed.
I leave it up to you, if you want to call this construction an antenna.
However, there are stories about this antenna, where the performance comes
close to the power of a dipole.
This may be explained by the fact, that the feeding line acts as the main
radiator.
Some installation instructions specify, that the feeding coax shall hang free
and that its length shall be half wavelength or multiple of this.
In this case we end up with a half wave radiator, fed by the EH.
So far my summary about the EH-antenna.
With best 73's
Felix HB9ABX
Addition August 6th, 2005
Writing jokes ...
--------------------
A Message from Karl, DJ4FO "So far we only could read the fantastic
information from Felix. Is he not telling us big jokes ? 73 from Karl, DJ4FO"
leads me to write you my following experience with the EH Antenna:
(The EH Antenna is a short antenna with a length of 2% of the wavelenth, or
shorter).
I would be very pleased to conduct a antenna test with this type of antenna.
On the HAM RADIO fair in Friedrichshafen this year I saw the motorhome from
ARNO, the european manufacturer of this antenna, which is sold by WIMO:
The EH antenna was mounted on the motorhome and I was asking them, for which
band the antenna serves.
They told me, it's the 40m antenna.
Then I told, that my station is just on the side and I would like to make a
radio test with their antenna.
Now they began to search all type of excuse, that no test could be performed,
at no day, at no time ...
Interesting, isn't it ?
By the way, WIMO specifies a gain of 0 to +2 dB of the EH antenna !
And the user reports I received from my packet survey indicated -10 to -20 dB,
or even less.
Question: Are we not told a big joke by them ?
The manufacturer specificatons can be found at:
-
https://web.archive.org/web/20060510154324/http://www.eh-antenna.com/library/EH_ANTENNA_FOR_HAMS.pdf
If someone knows a user of the EH antenna close to Basel I would be very
grateful for obtainig this information, as I would like to see him and conduct
a antenna comparison and would let you now the result here.
Update: 2.12.2006
Now the expected comparison with EH-antenna could
be performed on Novemver 30th.
see: http://hb9abx.no-ip.biz/ant-dec01-06e.htm
Result: Comparing EH against Roomcap:
EH is 10 db less !
73 de Felix, HB9ABX (felix-abx at gmx.ch)
Read previous mail | Read next mail
| |
