Buck wrote:
On Thu, 08 Mar 2007 08:03:56 -0800, Richard Clark
wrote:

On Thu, 08 Mar 2007 05:24:52 -0500, Buck
wrote:

If an OCF is shorter than 1/2 wave for the frequency of operation, it
will not perform as well as the 1/2 wave dipole.
Hi Buck,

Modeling would suggest otherwise.

The difference between a 1/4 wave center fed and off-center fed (at
10% from the end) is about a 12% increase in real resistance, and
.25dB gain improvement, both favoring the off-center fed.

Are you comparing short antennas to long antennas? If so, it wouldn't
be a surprise, would it?

Coming in late, did I miss someone's extravagant claim that a OCF
could do better?

73's
Richard Clark, KB7QHC


Sorry, I haven't been able to find replies until now- musta been a news
server burp or something..


The original comment was that a multiband OCF antenna is a
'compromise' antenna and wouldn't be as good as dedicated 1/2 wave
dipole cut to frequency (or so I understood it.)

If a 135 foot OCF were compared to a 1/2 wave 160 meter dipole, the
OCF would lose, but if it were compared to a 20 meter dipole, it would
have gain in the direction of various lobes.

And I'm not sure I would define those lobes as something other than a
compromise. If the lobe is in a good place for you, fine. If not, not so
fine.


Yes, the comparison is between different length antennas, and you are
right, generally speaking, the longer, the better. (no doubt someone
can find an exception to the rule, but that isn't the point of this
discussion.)

I'm a little dense here. 8^) Is a antenna cut for a half wavelength at
80 meters a better antenna at 10 meters than an antenna specifically cut
for 10 meters?

I'd also have to go back and look, but isn't the SWR on some bands on
the Capacitive reactance end, even though it may be 50 ohms?

I know my old Icom did not like capacitive reactance very much.

The idea that an OCF is superior to a dipole, and certainly Richard's
statements would indicate that; makes me wonder why everyone isn't using
them!

- 73 de Mike KB3EIA -