[Elecraft] EH Antenna Patent

[Larry Weaver]

At 10:49 PM 2/25/2003, George, W5YR wrote:
>What is "E-only" or "H-only" radiation?
>
> From the words of the popular song, Maxwell says " You can't have one
>without the other!"

I have no idea. The basis of propagation is the continual exchange of 
energy between the E and H components. I think it's a case of a 
little  knowledge being misunderstrood leading to an incorrect result which 
sounds good.

Antennas are wonderful. The large number of variables, most of which can 
not be controlled, is the difficulty. At time in my career I considered 
antenna design. When I discovered that you applied the theory and then 
spent the next two years trying to get it's performance to approach what 
you wanted, I changed disciplines.

I'm amazed that the misunderstanding persists. A short antenna has low 
radiation resistance so any ohmic resistance lowers the efficiency. Until a 
new physics is discovered and the laws  of electromagnetics  are revised, 
that's the summation. Who was worked with what antenna proves little other 
than shortwave propagation can deliver strong signals at long distances 
with little radiated power. People have made contacts when connected to a 
dummy load. The difference begins to show up in a pileup or when you 
compare antennas directly yourself.

Such a comparison was done at 14.1 MHz by the HF Pack group on antennas 
suitable for backpacking or pedestrian mobile operation. One antenna in 
particular was a good example of the performance of very short antennas, 
the Miracle Whip marketed for the FT817. It's 57 inches long and ha a small 
toroid for tuning. The Miracle Whip was one of the lower performers having 
a field strength 10.5 dB (~2 S units) below a quarter-wave dipole). This 
number was obtained using a counterpoise (or one radial, take your pick. If 
you look at the Miracle Whip web page, it says in several places 
"counterpoise free operation." HF Pack's meassurements without a 
counterpoise gave a field strength 30 dB below a quarter wave dipole.

Ron's message about the difficulty of such tests is correct although I have 
found that by spending enough time comparing, if one is better than the 
other it shows up.

I operated portable in Maine during last year's Field Day. Initially I was 
using a commercial vertical and having some difficulty working peopled. I 
put up my trusrty 20m dipolwe and began working people. With both 
available, I switched back and forth and the dipole usually was better than 
the vertical. Of course in a different environment, like on the edge of a 
body of salt water, the story would have been much different as shown by 
Team Vertical in the DX contests.

My advice on antennas is firstly, put something up and get on the air. Any 
antenna always works better than no antenna. Secondly, be highly skeptical 
about claims for the performance of short antennas. If that's all you think 
you can use, don't spend big bucks on something with outrageous claims. 
Probably the best and least  expensive solution is, as L.A. Moxon, G6XN 
pu9t it in hisd book, "HF Antennas for all Locations," "a random hunk of 
wire." I have convinced several local amateurs to try it and they haven't 
been disappointed. I've used them for years when in conditions where 
antennas weren't allowed. Made out of thin wire, no one knows there is an 
antenna but you.