Interesting project. My generalist, non-expert suggestion. There are
many variables you must consider, not the least of which are the
electrical properties of the components, such as the length, velocity
factor, diameter, resistance in circular mils, inherent impedance and
capacitance of any conductor or radiator, the effects of any dielectric
present, capacitive and inductive coupling with other objects in the
vicinity, and many other factors.
I am a big fan of verticals, but I usually work in the other direction:
I set the length of the vertical element, and adjust the length and
angle of the radials to effect a good match, but, it sounds like you
want a set, or multiple sets, of known radials as an ersatz control
group, against which you will judge the effects of different vertical
radiators.
I suggest you consider and measure / record all the factors you can, and
build a set of control radials for your experiments, and use them for
each individual experiment, and see what happens. You cannot control or
account for all factors, but unless you start someplace, you will go no
place. Build a set of radials and use them as a reference, and see what
you get... assess the data... regroup... re-formulate ... and determine
what to do next.
I suspect the guy to ask is Rudy Severns, N6LF, who is the guru of
vertical antenna testing.
Happy days, good luck.
-------------------- JHR -------------------------
On 7/26/2014 9:27 AM, CRAIG W BEHRENS wrote: curious about and I to be
able to see what the differences are in the lengths of antennas based on
what materials of different types and sizes that I use.
> _____________________________________________________
On 7/26/2014 9:27 AM, CRAIG W BEHRENS wrote:
I'm fooling around with custom portable Vertical array antennas for portable
and DXpedition use.
I was wondering if anyone in our list Brain trust had a favorite way to cut
wires to a (reasonably precise) 1/4-wave length.
(Yes, I can measure and No I don't want to model, I want to field test and
calibrate.)
What I want to do is have an elevated vertical (say base at 8'-10'), and add a temporary
1/4-wave "reference" counterpoise wire with a 20-degree downward slope.
Then, use this set-up to adjust whatever physical items I'm using for the
vertical element to get a 1:1 match, calibrated to the radials length.
I want to end-up with a balanced antenna that is resonant and does not require
a tuner (given that I'll have some minor adjustments to fine-tune the antenna's
match at different locations).
So, theoretically, the vertical could be made of 6-inch diameter aluminum
tubing (not likely in the field), insulated or non-insulated wire of any size,
or whatever.
I'm also curious about and I to be able to see what the differences are in the
lengths of antennas based on what materials of different types and sizes that I
use.
Ideas???
Thanks.
72/73,
Craig W. Behrens--NM4TK3, KX3, K2, K1 +++
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