30/20 vertical?
 

Hi,

For 20m I am planning a quarter wavelength vertical radiator with 4
eighth wavelength radials, mounted 12 feet high.

If I add another 4 radials cut an eight wavelength for 30m, will it be
easier to operate on 30?

Thanks,

The Eternal Squire

30/20 vertical?
 

wrote:
If I add another 4 radials cut an eight wavelength for 30m, will it be
easier to operate on 30?

Doesn't much matter if they are buried radials. I'm wondering
if a short vertical with long elevated radials would result
in an "off-center-fed" vertical.
--
73, Cecil http://www.qsl.net/w5dxp

30/20 vertical?
 

You did not say what your vertical radiator material is. Make it out of
wire (support it with PVC tubing), then you can put up 2 vertical radiators,
one for 20m, the other for 30m fed by the same coax. I guess this would be
a "Fan Vertical". Its based on a W6SAI design published in 1990. I've done
it with 10/15/20m radiators and it works well with elevated radials made
from TV rotator wire.

Good luck,

Bill, W4WNT
wrote in message
oups.com...
Hi,

For 20m I am planning a quarter wavelength vertical radiator with 4
eighth wavelength radials, mounted 12 feet high.

If I add another 4 radials cut an eight wavelength for 30m, will it be
easier to operate on 30?

Thanks,

The Eternal Squire

30/20 vertical?
 

For 20m I am planning a quarter wavelength vertical radiator with 4
eighth wavelength radials, mounted 12 feet high.

1/8 wl radials, with an elevated ground plane won't work
worth a hoot. They won't be resonant.

If I add another 4 radials cut an eight wavelength for 30m, will it be
easier to operate on 30?

Not really, unless you have a way to tune the radiator.
All elevated radials should be 1/4 wave long, unless a
case of using longer, such as 3/4 wave. 1/8 radials are
ok ground mount, but not elevated. Elevated radials must
be tuned and resonant to really work.
MK

30/20 vertical?
 

I'm wondering
if a short vertical with long elevated radials would result
in an "off-center-fed" vertical.

Not the way I see it, just as long as all the radials are
equal length. The reason I don't see it, is the radiation of the
radials should pretty much cancel if all are equal. Not
quite the same as the single radial in that situation.
If you had one radial, maybe so...
MK

30/20 vertical?
 

wrote:

I'm wondering
if a short vertical with long elevated radials would result
in an "off-center-fed" vertical.

Not the way I see it, just as long as all the radials are
equal length. The reason I don't see it, is the radiation of the
radials should pretty much cancel if all are equal. Not
quite the same as the single radial in that situation.
If you had one radial, maybe so...

I just ran one on EZNEC. The feedpoint is at 23 feet and there
are four 23 foot radials drooping at 45 degrees. (I already
had this one modeled.)

With a 23 foot vertical section, the feedpoint resistance is
56 ohms on 10.2 MHz. 234/10.2 = 23 feet

With a 12 foot vertical section, the feedpoint resistance is
84 ohms on 16.4 MHz. 234/16.4 = 14.2 feet, 2.2' longer than 12'.

It looks like (with slanted radials that radiate) there is an
"off-center-feed" effect, i.e. longer radials require a shortened
vertical section.
--
73, Cecil, http://www.qsl.net/w5dxp