Jeff Liebermann wrote:
Chevy454 wrote:

How effective is it to cut a one-band dipole for the highest frequency
desired and clipping an extension on one leg to get low SWR on lower
frequencies?
Ken KC2JDY

What band? What frequency range? How much space do you have? Numbers
are always helpful.

I dunno about an asymmetric dipole. I've never seen it done, which
makes me suspicious. It should be very easy to model to see what
happens. Numbers?

If you want bandwidth from an HF dipole, look into a cage or birdcage
antenna. It's especially effective at 160 and 75/80 meters. There's
no increase in gain over a dipole, but the usable bandwidth is much
better.
Even better, is a biconical, which is a cage antenna where
all the wires come together at the feed point, and are spread into a
cone shape at the ends. You can get several decades of usable
bandwidth out of a biconical with a fairly constant gain. That's why
it's used for EMC/RFI testing:
http://www.smeter.net/antennas/wire-cage-dipole.php
http://www.arrl.org/news/stories/2001/05/03/2/
http://personal.ee.surrey.ac.uk/Personal/D.Jefferies/antennexarticles/cage.html
http://jproc.ca/rrp/whitehorse.html (bottom of page)
http://images.google.com/images?hl=en&q=cage+dipole
http://www.smc-comms.com/cage_dipole.html


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

I use a 4-wire cage inverted vee on 80m. With it cut a bit long (1:1 at
around 3650 KHz), it's barely 2:1 at 4000KHz. Spreaders are 1/2" thinwall
PVC... 24"x24". I used the handy design program at http://www.smeter.net/.

73,
Bryan WA7PRC