"art" wrote in message
ps.com...
On 20 Sep, 22:39, Roy Lewallen wrote:
Trying to phase two antennas that close together at that frequency range
will be an educational experience at best, but more likely just an
exercise in frustration unless you have much more patience than average.
Such an array will be hyper-sensitive to everything. You might be able
to fleetingly see a null after a lot of tweaking, but I seriously doubt
you'll even get that. A tiny change in frequency, wiggling of the whips,
or even movement in the vicinity of the whips will have a profound
effect on any null you might see.

If a null from a small antenna is what you want, you'd have much better
luck with a carefully constructed and balanced ("shielded") loop.

Roy Lewallen, W7EL

Let me clarify some of the remarks made. A efficient antenna is when
the wire is
one wave length long and fed at its extremities. This can be
circumvented on a loop
by winding the 1WL wire on a non conductive hoolah loop both in a
clock wise and counterclockwise
in a overlapping method ( insulated magnet wire preffered )
such that the windings inductance balance to zero for a resistive
impedance
at the feed point The windings may have to be stretched some what to
balance outany stray capacitance added
or a broadcast type variable capacitor can be added if one is lazy.
The bandwidth is broad enough on most bands with a resistive impedance
of around 50 odd ohms.
If one deviates much from the desired frequencylength one will see a
resistive impedance
in the single digits so take care with the wave length measurements
This loop design based on Gaussian laws provides a broad bandwidth
with smaller physical size
compared to the standard magnetic loop design together with extra
gain. And yes one does not
need that expensive high voltage variable capacitor required for
movement around the band as required with presently known loop
designs.
By the way the element can be jumpered for use on other bands!
Have fun
Art KB9MZ
PS I have written a somewhat amaterish thesis on Gaussian antennas
for which I have applied for a patents, I am sure that a scan of past
posts on the subject will reveal the URL which I have not put in my
memory box.
Amateurs have not used this new design method as they are happy with
existing
arrays knowing that all is already known about antennas and all later
designs
must be fraudulent
Art KB9MZ....xg


Thanks, Art (and others). I'll do a few searches on Google, and see what I
can come up with.

Much appreciated.

Dave