Comments on: Short 40m dipole antenna, part 2 http://on3jt.byze.be/short-40m-dipole-antenna-part-2 Blog and website of a Belgian ham radio operator who likes to build antennas and other projects. Fri, 09 Dec 2011 15:20:32 +0000 hourly 1 http://wordpress.org/?v=3.1.1 By: Joost http://on3jt.byze.be/short-40m-dipole-antenna-part-2/comment-page-1#comment-50 Joost Fri, 02 Jan 2009 14:51:37 +0000 http://on3jt.byze.be/short-40m-dipole-antenna-part-2#comment-50 No not yet. But do you really mean 20m ? I have a friend that has built a shortened 40m rotary dipole and from what he's says I can assume that I works pretty good. The problem at the moment is that I first have to finish my remote antenna switch and install the necesarry cables. I have now just 1 cable for V/UHF and one for HF. I cannot get fast on the roof to switch antenna's :-) And with current temperatures of -7 ° Celcius I'd rather stays indoors... No not yet. But do you really mean 20m ?
I have a friend that has built a shortened 40m rotary dipole and from what he’s says I can assume that I works pretty good. The problem at the moment is that I first have to finish my remote antenna switch and install the necesarry cables. I have now just 1 cable for V/UHF and one for HF. I cannot get fast on the roof to switch antenna’s :-) And with current temperatures of -7 ° Celcius I’d rather stays indoors…

]]> By: James Puah http://on3jt.byze.be/short-40m-dipole-antenna-part-2/comment-page-1#comment-49 James Puah Fri, 02 Jan 2009 08:14:11 +0000 http://on3jt.byze.be/short-40m-dipole-antenna-part-2#comment-49 Hi Joost, Have you tried the short dipole on 20m? I live in an apartment at 16th floor (concrete with reinforce steel bar buidling) and have problems with proper RF ground and might have space to put out a dipole not exceeding 9m (end-to-end) and about 0.8 meters away from the wall. Best regards James Puah 9V1JP Hi Joost,
Have you tried the short dipole on 20m? I live in an apartment at 16th floor (concrete with reinforce steel bar buidling) and have problems with proper RF ground and might have space to put out a dipole not exceeding 9m (end-to-end) and about 0.8 meters away from the wall.
Best regards
James Puah
9V1JP

]]> By: Joost http://on3jt.byze.be/short-40m-dipole-antenna-part-2/comment-page-1#comment-32 Joost Thu, 22 May 2008 15:59:57 +0000 http://on3jt.byze.be/short-40m-dipole-antenna-part-2#comment-32 Hi Mark, I agree with your findings, the problem is that I don't have that much room. Another idea is to make a magnetic loop 3m in diameter. Still a compromise I know. But I like to play with different antenna designs. 73 Joost ON3JT Hi Mark,

I agree with your findings, the problem is that I don’t have that much room. Another idea is to make a magnetic loop 3m in diameter. Still a compromise I know. But I like to play with different antenna designs.

73 Joost ON3JT

]]> By: Mark, PA5MW http://on3jt.byze.be/short-40m-dipole-antenna-part-2/comment-page-1#comment-31 Mark, PA5MW Thu, 22 May 2008 10:06:19 +0000 http://on3jt.byze.be/short-40m-dipole-antenna-part-2#comment-31 Hi! I have had some similar trapped dipoles in the past and found: - small bandwidth - outside the SWR 2.0 range the efficiency drops quite substantial - height above ground/roof & other structures nearby have a great impact on SWR and bandwidth(again) My 2x 12m95 copper wire + 450Ohm twinlead +balanced ATU worked soooo much better. Currently I use DX-Wire from http://www.dx-wire.de, Type A wire; which is polyurethane coated copperclad steel. It becomes invisible at a distance of only 5mtrs '73 Mark,PA5MW http://pa5mw.blogspot.com Hi!

I have had some similar trapped dipoles in the past and found:
- small bandwidth
- outside the SWR 2.0 range the efficiency drops quite substantial
- height above ground/roof & other structures nearby have a great impact on SWR and bandwidth(again)

My 2x 12m95 copper wire + 450Ohm twinlead +balanced ATU worked soooo much better.

Currently I use DX-Wire from http://www.dx-wire.de, Type A wire; which is polyurethane coated copperclad steel.
It becomes invisible at a distance of only 5mtrs
’73 Mark,PA5MW
http://pa5mw.blogspot.com

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