Triband end-fed half wave antenna for portable use

Describing and demonstrating an end-fed multiband antenna for portable use.

It’s a full-sized half wave on 20 metres and a loaded half wave on 40 metres. The antenna also works on 10 metres. It’s not recommended for use on other bands.

A broadband transformer replaces the antenna coupler. While it’s likely less efficient than an L-match antenna coupler this arrangement allows instant band changing. Its only disadvantage is that its bandwidth on 40 metres is somewhat narrow (150kHz approx) when used with the loaded half wave wire described.

Similar to the Par Endfedz design this transformer will work on other bands with a half wave wire. With 10m of wire I could get low SWR (as indicated by the FT-817’s indicator) on 20 and 10m. 20m of wire gave those two bands plus 40 and 15m. Some variation of the trimmer will however be necessary so it’s worth carrying a small screwdriver, preferably attached to the transformer unit to prevent loss.

There’s a bit of cut and try in construction. Those wanting a premade unit should investigate either the Dutch HyEndFed or the American Par Endfedz 40/20/10m end-fed models. Both have received good reviews on eham.net .

Check these links for further info:
* http://pages.suddenlink.net/wa5bdu/ef…
* http://pa-11019.blogspot.com.au/2012/…
* http://www.hamradio.me/antennas/lnr-p…
* http://www.eham.net/ehamforum/smf/ind…
* http://pa3hho.wordpress.com/antennes/…
* http://www.hyendfedantenna.nl/joomla/…
* http://www.parelectronics.com/end-fed…
* http://www.eham.net/reviews/detail/5105
* http://www.mwrs.org.au/wp-content/upl…