RadioBanter - Antenna Theory

RadioBanter (https://www.radiobanter.com/)

- Antenna (https://www.radiobanter.com/antenna/)

- - Antenna Theory (https://www.radiobanter.com/antenna/103145-antenna-theory.html)

Hello Felix,

Reading your text, I also get a somewhat unpleasant feeling.

As I mentioned in my first contribution, A good GSO is not a
representative figure for efficiency, because the difference between
10% and 100% radiated power is 10 dB.

I am very curious to know your test setup for assessing efficiency. For
me efficiency is ratio between radiated output and input. Matching
networks are considered part of the antenna.

At low frequency, determining efficiency is difficult. You probably
must hire a helicopter to determine the 3D radiation pattern, or you
must rely on "traditional antenna knowledge".

In some cases the efficiency may appear to be higher (based on loss
measurements). If your antenna is close to a structure that has
reasonable coupling to your antenna, It may act as a re-radiator (or
absorber).

I like people that don't follow straight paths; many times it resulted
in better products or better understanding. However, when you claim a
certain efficiency, you should fully state how you measured efficiency
and under what circumstances to enable review by others.

I am a little bit skeptical to efficiency claims, especially when I
have to pay in advance. I was professionally involved in measurements
of very small UHF antennas with wide band, high efficiency
characteristics. In most cases the measurements against standard
antennas did not show the characteristics claimed.

I believe you should give more details about your antenna (mechanical
and electrical).

Best Regards,

Wim
PA3DJS

On Wed, 13 Sep 2006 11:57:28 +0000, Felix
wrote:

Dan, N3OX, please no flames. That is not the correct style here ...

You are criticising by error, or by ignorance.

Hi Felix,

Given your statements that follow, it appears that Dan IS criticizing
about error and about ignorance:

I did the measuring of the efficiency by feeding the RoomCap antenna
with 1 KW HF,
havinga VSWR below 1,1

Your claims are based on very thin technical knowledge - and your lack
of experience shows. VSWR is not an indication of efficiency - far
from it. I seriously doubt you know how to measure the V of VSWR.
Your meter measures power, not V. Your understanding of the SWR
versus efficiency relationship also reveals a lack of basic
understanding. For small antennas, low SWR can be solid proof of high
inefficiency. The simple fact of the matter is that no small antenna
presents a load that is remotely close to any standard transmitter's
output Z, nor any commercial transmission line.

I fully expect you will attempt to claim matching solves this. When
you do attempt that, we will clear up your lack of experience there
too.

and the result: Less than 70 W heat is produced
by the
antenna, and, as energy can not be destroyed, 930 W was radiated by the
antenna.

In fact, you do not prove you measured 10W heat, nor 20W heat, nor 40W
heat, nor "less than 70W heat." You cannot even prove you radiated
930W watts. There are methods to "prove" these claims, and you don't
show any knowledge of those basic principles. Relying on one
definition (poorly extracted from a text) is not sufficient. It may
qualify for sales, but this is not a sales group and you are not going
to find customers here with your poor quality of discussion.

This leaves us with one question: "What do you expect to achieve
here?"

73's
Richard Clark, KB7QHC

In article , Richard Clark
wrote:

This leaves us with one question: "What do you expect to achieve
here?"

73's
Richard Clark, KB7QHC

Hello, and if you're a good enough salesman and have at least one
university professor to explanation your "interpretation" of
electromagnetic theory, you could rename the antenna "Son of CFA" ;-) At
some point, however, a prospective customer is going to require some
verifiable test data.

All kidding aside, the challenge is the use of technique(s) that allows
for the direct or indirect measurement of radiation resistance and loss
(structure including any earth loss in the vicinity of the feedpoint)
resistance over the operating frequency range. A measurement of the real
(resistive) part of the antenna feedpoint impedance can only provide the
sum of both types of resistance. We know how much power is being
dissipated (heat + radiated) but that's all we can know from this one
measurement.

There is also the shape of the radiation pattern...but that is another
matter. Sincerely, and 73s from N4GGO,

John Wood (Code 5550) e-mail:
Naval Research Laboratory
4555 Overlook Avenue, SW
Washington, DC 20375-5337

Felix,

I apologize for the strong language.

I would believe that you've designed and built a quite good mobile
antenna that impresses veteran topband operators. However, it's not
turning 93% of the power you're feeding it into radiation. I barely
believe that it might be taking 7% of the power you're feeding it and
turning it into heat in the antenna, but what about the ground return
losses in the earth? These are, of course, proportional to the square
of the current flowing in ground system. You seemed to suggest that
your method of matching to the low radiation resistance is practically
lossless. Even if this were to be true, and there were no loss in the
matching network or the antenna conductor, you still must have a
connection to earth. If this connection is not perfectly conducting,
pushing all that current into it will result in high losses. For a
ground system with 1 ohm of ground loss, and an antenna radiation
resistance of 0.2 ohms, assuming a lossless matching network and
radiator, I get an efficiency of 12% over PERFECT earth. Taking the
ground reflection losses into account over average ground, it's about
5%. This is assuming PERFECT matching network and a very good (maybe
impossibly good?) grounding system. The ground return current has to
flow somewhere, the matching network I'm assuming is a black box. It
doesn't matter what it is or how novel it is, the ground return current
has to flow in your grounding system, and with an antenna as short as
yours, that's a LOT of current. You do realize that if you were
completely losslessly feeding 1kW into 0.2 ohms, the antenna current
would be 70.7A, right?

You won't notice a kilowatt's worth of power dissipation in your car
and the earth around it.

Felix, are you willing to do an experiment? Feed your RoomCap antenna
against another one as a dipole, adjust the matching network for a good
match, and feed 1kW into it and measure the heat produced in the
matching network and antenna, if it survives long enough to do so.

And another thing, Felix... even a full size, perfectly conducting 1/4
wavelength monopole with a practically lossless place for the ground
return currents to flow doesn't radiate more than about 30% of the
power applied to it anyway over average earth. The ground reflection
losses in the Fresnel zone dissipate much of the power. This is better
over better earth of course, but I doubt your antenna has some sort of
control over the soil conductivity and permittivity for tens of
wavelengths in every direction. You may wish to revise your claims of
93% efficiency down to 93% efficiency relative to a full size ground
mounted 1/4 wavelength monopole; it would be a more convincing untruth.

One further comment: I have a hard time believing that these are all
innocent mistakes.. It reflects badly on your character to make vague,
inaccurate statements about a miraculous antenna and then tell people
they need to dish out 30 Euros just to be able to try it. My apologies
for thinking you're a big scammer if you are merely a victim of your
own optimism.... I could see the argument that only 70W are being
dissipated in the antenna as convincing even the innocent experimenter
that he was on to something big! However, now you know the truth. If
you revise your claims with an eye to the reality of feeding a small
antenna against the earth, then I won't be so upset with you.

It is counter to the ham spirit to mislead people in this way, if
that's what you're doing, and only you know that. We are all trying to
learn RF engineering in our spare time, and it's important that the new
hams out there take their 38 bucks and apply it to their inverted L
project for 160m, or a copy of ON4UN's low band DXing book instead of
handing them over to you for the plans to one disappointing antenna.

73,
Dan

Antenna Theory - And ON4UNs book

d an antenna radiation
resistance of 0.2 ohms, assuming a lossless matching network and
radiator, I get an efficiency of 12% over PERFECT earth. Taking the
ground reflection losses into account over average ground, it's about
5%. This is assuming PERFECT matching network and a very good (maybe

new hams out there take their 38 bucks and apply it to their inverted L
project for 160m, or a copy of ON4UN's low band DXing book

Great advice Dan. That book, in my opinion, is the finest book ever
written concerning practical information for the HF operator. And I
have read them all.
You know, one thing that impressed me (and there were many) in that
book is where he admitted that previous versions were wrong in telling
us there was benefit to sloping the end of a Beverage antenna down to
the feedpoint. Simply running it vertically down is the same. To
readers of this newsgroup, if you have only read previous editions,
you should get the new one. It is completely rewritten.

Rick K2XT

Antenna Theory - And ON4UNs book

Rick wrote:
To
readers of this newsgroup, if you have only read previous editions,
you should get the new one. It is completely rewritten.

In a nutshell, what does he say about the delay/phase-shift
through a loading coil in the latest edition?
--
73, Cecil http://www.w5dxp.com

Antenna Theory - And ON4UNs book

[/email] (Rick) wrote:

d an antenna radiation
resistance of 0.2 ohms, assuming a lossless matching network and
radiator, I get an efficiency of 12% over PERFECT earth. Taking the
ground reflection losses into account over average ground, it's about
5%. This is assuming PERFECT matching network and a very good (maybe
new hams out there take their 38 bucks and apply it to their inverted L
project for 160m, or a copy of ON4UN's low band DXing book
...
Rick K2XT

I am sorry, that some people oppose so strongly
against what I said about my experience I gained
with the new HB9ABX Roomcap antenna.
They have no idea what they are talking about.
They criticize without having seen what they talk about.
The referenced antenna books describe what they know about antennas.
This is applicable for the traditional antennas, not for the
new concept of the RoomCap.

I know very good the losses that may occur in antenna systems
and especially in ground losses.
That is, why the RoomCap antenna has its own new grounding system
to prevent such losses.

If in the past all new discoveries were treated that way, the world would still be
flat and the earth would be the centre of the universe ...

---

If you are feeding the antenna with 1 KW real power,
and the in total, less than 70 W is converted to heath,
then 930 W is radiated by this antenna.

And the special grounding system is assuring that
the radiated power is not burned by the surrounding ground,
and is radiated efficiently into the space.

The result is, that I am told frequently:
You are the strongest station I hear presently
on this band.
That happend many time last week on 40m,
and was reported by many UK stations.

---

And read the comment I received from my 160m tests
(with a 3 m long radiator):

Hello Felix,
after our fantastic QSO on 160m we (Peter,DL1BLD)
and I (Heino, DJ5ER) we were completely surprised
with what a strong field strength you arrived in Bremen.
We would like to know how such an antenna can
be built (also for the other HF bands).

73 from Bremen .... (QRB = 600 Km)

- and -

Hello Felix.
Congratulations for your antenna work.
You are the first mobile station on 160 meters for me.
Even you are stronger as the Germans on 160 meters.
I give you on 1.862 Mhz S 9+15 db in the peak!!
The background noise level was S 8 during our QSO

Hope to meet you agn for next report and test.

Piet Schipper / PA0QRS (near Rotterdam)

Schipper mobiele Telecom
2931 LH Krimpen a/d Le
--- --- ---

Would you obtain such reports with
a "dummy load" antenna ?

73s
Felix HB9ABX

Ah, the perennial cry of the pseudoscientist. I am misunderstood! My
idea will change the WORLD.

But then, you offer no real evidence. You're basically giving a
supernatural explanation for the operation of the antenna. The RF
current flow is a ghost.. it's a haunted antenna. What measurements do
you have to show that your grounding system does what you say?

A very, very inefficient antenna can get you good signal reports.
You're trying to get people to send you cash for your haunted antenna,
so you won't do real measurements. You don't really know how much
power is being radiated by this antenna, and never will we, unless we
send you money.

Dan