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This is a fascinating subject, but materials and construction info seems sketchy, soooo …
http://www.eh-antenna.com/EH_theory.html
This is a fascinating subject, but materials and construction info seems sketchy, soooo …
http://www.eh-antenna.com/EH_theory.html
I’ve seen a commercial antenna designed to operate in the AM BCB. It has two 6″ dia. x 4′ cylinders stacked one above the other with the tuning coil at the bottom of the bottom cylinder and the capacitive “chamber” between. It’s overall resistance is supposed to be 77ohms.
So we have the E portion (electric) in the mathematically vertical and the H (magnetic) portion in the mathematically horizontal, comprising a dipole. But the cool part is that its design basically creates a situation where the magnetic field produces adequate ground on it’s own.
It seems to me that this little guy fits the letter if not the intent of Part 15 regulations restricting the antenna length, and, further, it doesn’t require ground radials. The whole point of the design is to eliminate an AM station having to have a chunk of property to lay ground radials yet perform as if it did (maybe even better).
So the questions are: 1) Will it work with 100mw? 2) What are the “cylinders” made of? 3) How many winds in the tuning coil for a given frequency (in the AM BCB the commercial versions only work from 1200Hz up), seeing how its in the magnetic portion?
Some of us plebes are going to need some help ingesting the theory.
Total posts : 45366Not to be a pessimist but you will probably receive nothing but ridicule for considering the EH antenna design.
It will be dismissed as a very short, lossy dipole which only radiates primarily from the coax shield or ground wire.
It has been tested and reported on by several Amateur Radio operators. Some find it useful, others not.
Died in the wool engineers will not consider it as it fails to follow conventional design practice.
Total posts : 45366Does the FCC approve the use of EH antennas?
Are any licensed stations using EH antennas?
Total posts : 45366“Stoned and Cast Aside”
There you go talking about my freshman year at college again!But seriously, here are some links:
Total posts : 45366Aha! An EH antenna is kinda opposite a normal monopole with grounding. It can’t be close to the ground at all … e.g., the commercial version needs to be mounted at least 1/8 wavelength above ground, or around 80 feet or so, to become viably efficient. IOW, it may be a good choice where there is no large plot available to lay ground radials but doesn’t have height-above-ground restrictions.
They might be less sensitive to bandwidth, but I’m guessing they will still be a real nuisance to match.
KYET in Williams Arizona s supposed to get one, but everything I’ve found says they’ve bveen silent a long time.
Total posts : 45366Blare: So, SCWIS, what happened your sophomore year that was different?
Defender: “OBJECTION!”
Blare: “I withdraw the question.
Total posts : 45366Died in the wool engineers will not consider it as it fails to follow conventional design practice.
We don’t need no steenkeeng “conventional design”.
To me, a really large part of this, as a hobby at least, is experimental. IOW, if I lived on the top floor, or had easy access to the roof, of an 8-story (or more) building, I would happily invest time in trying an EH antenna for Part 15 AM. It’s already been shown that it can have over 90% efficiency in such a case.
Total posts : 45366If my memory serves Ermi posted quite an extensive analysis of this type of antenna but unfortunately it was lost when the site crashed. Based upon what I have read I wouldn’t buy one nor invest in the company.
Regarding “dyed in the wool engineers”, engineering practices are applied to innovation. The innovation is in the unique application of the designs and laws of physics. Being one of these engineers does not stop me from experimenting and innovating.
The nice thing about the part 15 hobby is that one can experiment and innovate without being an engineer.
Neil
Total posts : 45366‘cept I didn’t have any plans whatsoever in investing in a company or of buying an antenna at all. I was talking about investing in research time, materials, and my own labor to build one … experimentally. But now that my reading uncovered enough of the theory, I have nowhere to raise an EH antenna to a height where it could be expected to work anyway.
So… probably back to working on fractal and loop ideas. ITMT, I guess I’ll start winding a coil for my next TX.
Total posts : 45366The basic idea of the CFA, and related antennas (such as the EH), is that the E and H fields are generated separately, and are then combined directly at the antenna to produce the Poynting vector, EXH, with high efficiency. No theoretical justification for this view is given by any of the CFA/EH proponents. Prof. Valentin Trainotti is the only person who has dealt with The CFA with an exact theoretical analysis. A PDF copy of Trainotti’s IEEE paper may be obtained from the references section of the Wikipedia article on crossed-field antennas. But the CFA/EH proponents do not accept Trainotti’s conclusions because they are based on conventional electromagnetic theory (i.e. Maxwell’s equations with the appropriate boundary conditions), and the proponents claim to have discovered a new electromagnetic principle that is not based on conventional theory. Similarly, the proponents do not accept the results of NEC or other antenna analysis software because they are also based on conventional theory. And here the matter apparently rests.
I am presenting here a more obvious argument against these sorts of antennas than electromagnetic theory. I just ask you to accept the evidence of your own eyes. Look at any photograph of an EH antenna in operation. In most cases, you see a short and fat vertical dipole on top of a tall post. Some of the earlier EH antennas are discones rather than dipoles. It really doesn’t matter. This short antenna is resonated with a loading coil, and the tuning network containing the loading coil is driven by a coax cable. Will the EH antenna work at ground level? The proponents say NO. A long vertical coax cable is necessary to make the EH antenna work. The logical fallacy of “category error” in this case is what actually comprises “the antenna.” The EH proponents call the antenna the elevated fat dipole, or discone. In reality, the antenna also comprises the long coaxial cable connecting to the tuning network. The coaxial cable is the main radiating element. Is the combination of the coaxial cable and the dipole/discone really compact? It is not. The EH antenna is not a small antenna, like the proponents claim.
Added note: A “category error” is a logical fallacy based on calling something a thing that it is not.
Total posts : 45366Ermi I enjoyed your explanation of the “category error” in the case of the EH antenna. You remind me of another story that made it into the news not long ago. Teenagers somewhere in Asia invented a solar collector comprised from human hair, at last opening the way for inexpensive solar panels that even home hobbyists could make just by gathering hair.
I sent the story to an energy specialist and he knew right away it was another hoax.
Oh good. The link is still here. Check it out
http://www.iol.co.za/index.php?set_id=1&click_id=31&art_id=iol1252482194588H624
Total posts : 45366A category error might also be called a lie.
Total posts : 45366The question of using the theoretical EH type of antenna has been discussed for many years. And historically, the antenna system has shown some practical merit. However, like many ideas, this one has been destined for the bone pile from the beginning for Part 15 AM BCB stations; And for a variety of reasons its DOA.
Just a thought; aren’t dead horses stuffed and left standing in museums? And oddly enough, people pay good money to view the dead horse. Some are even foolish enough to want to ride it.
Or better yet, buried so that they don’t stink up the world the rest of us live in; returned to the dirt from which they came.
The other side of that coin: When studying the anatomy of a horse, accurate taxidermy can be valuable for those without access to the real thing, and without having to clean up after it.
It seems, here, when hunting for dead horses that we sometimes bag a few.
Total posts : 45366Does a tight curl increase the efficiency of the hair conductor. Will the hair conductor punch your ticket if your on the wrong train? It seems that inquiring minds need something to think about. How about whirled peas?
Total posts : 45366You might enjoy this edition of the Crawford engineering newsletter (9/08). The engineers actually got a hold of and tested an E-H antenna. Their conclusions were not very encouraging.
http://www.crawfordbroadcasting.com/~cbc/Local_Oscillator/September%202008%20Local%20Oscillator.pdf
I’m all for developing new approaches to AM antennas but, so far, nothing has proved really successful beyond the tried and true designs. The Kinstar is probably the newest accepted design. But the amount of land required for one is no different than a standard unipole two-antenna array and the Kinstar is non-directional.
c5
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