I was very charmed from the half wave antenna. It's has a large bandwidth with a low SWR and has no radials. At several sites I discovered the antenna from Rob PA3EKE and Ron PA3RK. An end fed for 10, 20 and 40m. I have no idea how they do that and that interest me because I would like to build such an antenna. Sorry Rob and Ron, but I donít want to buy the antenna, but I want to make one.

To find some info about this antenna there is always the good old Google. At several sites there is information and especially at
http://www.zendamateur.com. The topic about this antenna is 22 pages with info, discussion and questions see http://zendamateur.com/viewtopic.php?f=5&t=6682
I also found something about a transformer designed by PA0EJH. Information about this transformer can be found at PD7MAA (http://www.pa-11019.blogspot.com)

The transformer is a 1:49 en will be wound on an iron core FT140-43. Of course I try it to make it on a T130-2, but that doesnít work. This core has a too low permeability. I ordered a couple of cores at Frans Bakelaar in Julianadorp (http://home.kpn.nl/fbakelaar/ringkernen.htm). He has a perfect service, ordered at Sunday evening and at Wednesday I got the cores. The experiment can start!  I made the transformer according the drawing below.
I took 2 pieces of wire that we have firmly twisted for about 10cm. This twisted wire makes 2 turns around the core, followed by 7 turns from the long single wire. Then we have to cross en make another 7 turns.

After the transformer was finished I start measuring. Just as the monoband I connected a 4k7 resistor instead of the antenna. If I measure with the analyzer the SWR stays below 3 with a frequency range from 1.6-30MHz. That looks good so now I can start with the antenna
First I have to connect a wire from 10.1m long. Then there comes an inductor from 34uH
and then again a piece of wire from 1.85m. For 10 and 20m the inductor has high
impedance and will block these frequencies. For 40m the inductor makes the antenna
electrical 20m, a half wave length.

According the information from PA0EJH we can make the inductor from 91 turns on a
PVC pipe with 19mm diameter. The wire has a diameter from 1mm.  I had only 16mm PVC
so I needed 124 turns for an inductance of 34uH. A larger diameter is also possible,
how bigger the diameter, the less turns are needed.
PVC 25mm round, 1mm wire, 64turns wounded tight, Length about 64mm
PVC 32mm round, 1mm wire, 44turns wounded tight, Length about 44mm
PVC 40mm round, 1mm wire, 334turns wounded tight, Length about 33mm
Of course itís recommended to measure the exact inductance of the coil. I use an LC-
meter designed b y the VERON Meppel and is available via PE1ACB.

I have a telescopic fiber mast form 15m long and setup the antenna vertical. First I had
to trim the 10.1m wire a little bit for an SWR at 20m near to 1. On 10m the SWR is 1.5.
Now check at 40m., there was the SWR 1.3. No trimming required, itís just fine so. Now
I could test with the transceiver. Great signals and much less noise than my half size
Itís an easy to build antenna with a high rendament and great performance.  But if you
donít want to make the antenna you can buy one at Rob PA3EKE site
http://www.hyendfedantenna.nl/joomla/ They are from a high quality and absolute
worth the money to by one.
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