[Elecraft] My Experiences with EH antennas on 20 meters
Tony Wells
[email protected]
Mon Feb 24 05:19:01 2003
> Charles wrote:
>
> > The EH antenna really works, well. It's efficiency, as an antenna, is
on
> > the order of 95%, as compared to about 75% for the full size 20 meter
Vic wrote:
> How did you determine this? Do you know the radiation resistance? I
suspect
> the radiation resistance is very, very low...and as a result, so is the
> efficiency.
This debate reminds me *so* much of the mag loop debate of 15 years ago. The
problem with all this this stuff is firstly that antennas are not an exact
science, and probably never will be. Secondly the variable environment at an
individual's QTH , is , well , variable.
Like many others, I was not convinced about the effectiveness of mag loops
until I saw a well-built design in action - a 80M SSB contact across the
Atlantic on 50W. I've also seen some pretty poorly-built mag loops. Like
many others I also will not be convinced until I see a well-built EH in
action. I've scheduled my first EH build for end of this month. We'll see
what happens :-)
The plus points of the EH antenna, apart from being small, is that it is
easy to build using houshold DIY parts, and cheap as a kit to buy for
experimenting with. If you look at the patent application it also *might* be
able to provide something that no small HF antenna can offer - a highly
directional beam, using a dish.
The difficulty with the EH antenna is that like mag loops in the early days,
the guys that "invented" or "discovered" them are not good at communicating
their designs. This is not meant as disrespect. It's just life. Also, the
"ham" community is can slow at times in adopting new technologies ;-)
Two things will facilitate the wider adoption of interest in EH Antennas.
1. A regularly high-scoring DX contester needs to team up with a EH antenna
constructer and win some prizes using the antenna. Volunteers?
2. There needs to be clear and unambiguous wiring digrams and designs that
can be reproduced without error. This means that the docs and kit
instructions need to be produced by people that *do not* understand the
antenna theory, and have them reveiwed by people that *do* undertsand. I've
helped a tiny bit with this by entering into a "design dialog" on the EH
mail list and producing a wiring diagram on the yahoo mail list resource.
Similarly others have submitted their hand-drawn practical designs. This is
all good.
For more info on the subjects, here are the starting points to work from:
The main website:,http://www.eh-antenna.com There is a kit available.
The url for the patent is below. It will get groken up by your mail viewer,
so it may be easier to go to the web site and type the pat. no. in manually.
The patent no. 6486846
http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=/netahtm
l/search-adv.htm&r=1&f=G&l=50&d=PTXT&p=1&p=1&S1=6486846&OS=6486846&RS=648684
6
The yahoo mail list is at: http://groups.yahoo.com/group/eh-antenna/
Regards,
Tony
M3CJF
G7IGG
All mail in and out checked lovingly by hand, character by character.