[Elecraft] 80 Metre Verticals

[Chuck Chandler]

So... if I am planning to move to the high desert of New Mexico in a few
years, what is the best low-band antenna option?  I've used verticals over
lots of radials in Massachusetts and Mississippi with good success, but if
I'm up 6500 feet and the water table is WAY down there... what, a dipole?

73 de Chuck, WS1L

On Tue, Feb 28, 2017 at 2:18 PM, Guy Olinger K2AV <k2av.guy at gmail.com>
wrote:

> Concurring with Tom, assuming you have the polarity of the X correct, and
> there's more.
>
> A short 1/4 wave-ish vertical that shows R=57 in the R+jX expression is a
> vertical/counterpoise or radial(s) combo that has far too much resistance
> and is a dead giveaway for a considerably inefficient antenna and may be
> wasting 3 dB somewhere.
>
> A full quarter wave vertical over 60 1/4 wave radials should be showing
> 32-35 ohms at resonance, e.g. 33+j0. A theoretical 1/4 wave L in free space
> with lossless conductors should be 12-15 ohms. In the real world over real
> dirt with an efficient counterpoise, and lacking various possible
> real-world inefficiencies an L should be something roughly 25 ohms. Mine is
> 28 ohms on a calm day over dried out dirt.
>
> Frankly, if it really is efficient, 57-j130 sounds like a fairly *longer*
> than 1/4 wave-ish L aerial wire over an FCP without using an isolation
> transformer. A bad idea for a stack of reasons.
>
> Otherwise, there is likely a lot of dielectric material inside the bend of
> the L adding loss in the R measurement in addition to 32-35 ohms. An
> efficient L should show lower R yet to be efficient. Mine is 28 ohms,
> measured with an AIM4170 with a calibrated feedline factored out by the
> software. An occasional measurement right at the feed is always very close.
>
> In your case R = 57 instead of R = 28 probably means that something like 29
> ohms of that 57 is recoverable loss for some reason or other.
>
> 73, Guy K2AV
>
>
> On Tue, Feb 28, 2017 at 10:05 AM, Tom Boucher <tomg3olb at gmail.com> wrote:
>
> > Fred,
> > If your inverted 'L' was a bit less than a quarter wave long, it would
> have
> > been capacitive and showing 57-j130  (not plus). In which case you
> needed a
> > small inductor to match it to your 50 ohm coax, not a capacitor.
> >
> > 73,
> > Tom G3OLB
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-- 


===================
Chuck Chandler
chandlerusm at gmail.com
===================