[TowerTalk] Driving Point Impedance

Jim Lux jimlux at earthlink.net
Wed Feb 12 20:12:32 EST 2003


What element currents did you assume for driving point Z?  Phased 90 degrees
each step? Apparent driving point Z changes with element currents, of
course.
I've been looking at phased arrays a lot, and would be happy to check your
measurements. Why don't you post the actual measurements or the entire array
of Z?

The mutual Z for arbitrary spacings of 1/4 wave monopoles should be readily
available in tables, and, because it's linear, having 4 shouldn't make any
difference.  It's just a matter of distance between the two elements.

And of course, there's a paper in the recent Antennas and Propagation
Journal about how the "Carter" equations aren't necessarily valid when
elements are driven.

----- Original Message -----
From: "Denis" <dcoolica at planet.eon.net>
To: <towertalk at contesting.com>
Sent: Wednesday, February 12, 2003 7:27 PM
Subject: [TowerTalk] Driving Point Impedance


> I have a four in line vertical array for 80 meters that is in
> construction.  The verticals are .25 wavelength long and the seperation
> is .25 wavelength.  Each has 50   .25 wavelength radials.
>
> I have measured all the self impedances and the coupling iimpedances
> and from that I have calculated the mutual impedances and the driving
> point impedances.
>
> The driving point Z are as follows:
>
> Vertical 1         13 - j17.2
> Vertical 2         17.5 + j5.7
> Vertical 3         36.4 + j21.5
> Vertical 4         80.4 + 60.5
>
> I have seen numbers for a 3 in line array but no field values for a 4 in
>
> line array.  I was wondering if any one has built and
> measured/calculated the Driving point Z so I could see if I was in the
> ball park.
>
> Denis Ve6AQ   / VE6FI
>
>
>
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