[Elecraft] Less Than Perfect Antennas [was Flumoxed]

[Robert G Strickland]

Ron...

Would such an antenna cut for 80m, fed with ladder-line, and used on 
40m, be a better performer on either band than an 80-40m fan dipole fed 
with 72ohm coax? Leaving all other extraneous but influencing parameters 
aside. I have the second antenna; the weight of all that wire and the 
coax with a ferrite balun results in a significant sag. I'm wondering if 
the first antenna, lighter and higher in the air, would perform better? 
Thanks.

...robert

On 12/6/2018 14:54, Don Wilhelm wrote:
> That statement is true - however ---
> The problem is not radiation from the conductor, but how to get the RF
> current into the conductor and not in other unintended places.
>
> For those who want to build their own antennas, I suggest starting with
> a resonant dipole fed in the center.  That provides a good match for 50
> ohm coax, and a good current mode choke (balun) at the feedpoint keeps
> RF from flowing back onto the outer shield of the coax which can create
> a lot of RF in the Shack.
>
> Off Center Fed, and End Fed antennas can be made to work with more care.
>  The feedpoint impedance does not match coax, and special care must be
> used to keep the RF on the radiator rather than coming back into the shack.
> I realize that OCF and End-Fed non-resonant antennas are popular because
> they can be used on multiple bands, but there are problems feeding them
> while keeping the RF on the radiator and not in unintended places such
> as the shack.
>
> For those who want multiband operation, I still suggest a center fed
> radiator fed with open wire or ladder-line to a good current mode choke
> balun at transition point to coax is a better choice than OCF or end-fed
> antennas - keep the coax short and use a tuner that can match the
> resulting impedance.
> Make the length of the dipole approximately the length of a half-wave at
> the lowest operating frequency desired.  It will be more "tame" for RF
> in the Shack than many OCF or End-fed antennas.
>
> 73,
> Don W3FPR
>
>
> On 12/6/2018 8:56 AM, ANDY DURBIN wrote:
>> "RF current into a conductor will radiate, even if it's at eye level."
>>
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-- 
Robert G Strickland, PhD ABPH - KE2WY
rcrgs at verizon.net.usa
Syracuse, New York, USA