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TopBand: Pennant Report

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Subject: TopBand: Pennant Report
From: (Earl W Cunningham)
Date: Thu, 24 Sep 1998 03:55:03 EDT
Hi Tom,

You wrote:
>Can someone e-male me a description of the Pennant? I want to measure
>common mode impedance and balance sensitivity.

Do you have EZNEC?  If so, I'll send you the model file.

The Pennant is equilateral triangle-shaped, exactly like a pennant.  The
vertical side of the Pennant is 14' long and the upper and lower sloping
sides of the Pennant are 29' 10" long, meeting at a point 29' from the
vertical section.

The vertical section of my Pennants are 6' above ground at the bottom and
20' at the top.  The point is at 13' high and 29' away from the vertical
section.  This is exactly how I modeled it.

I feed mine at the point, with the termination resistor (900 ohms) in the
center of the vertical section, although it works just as well with the
feedpoint and terminations reversed.  It receives signals (cardioid
pattern) from the direction of the feedpoint end of the antenna, with a
deep null in the direction of the terminated end.

A report of your analysis of its common mode Z and balance sensitivity
would be most appreciated.

I wound a transmormer using a FT140-43 core per Peter's suggestion using
a 10-turn winding and a 35-turn winding with the windings separated as
much as possible on the core.   I used a turns ratio of 3.5 because I
feed the Pennants with 75-ohm coax, so this would closely match the
900-ohm Z of the Pennant.

After Installing the transformer, tests were made with K6NDV who is 4.5
miles away and in direct line with my Pennants.  On 160m,  F/B was only
6dB.  On 80m, F/B was 45+dB.  No check was made on 40m due to Will tx
antenna the is horizontally polarized.

We put some snap-on ferrite chokes on both the feedline and the 12-volt
wiring to the switching relay at the antenna end of these cables.  The Mu
of these chokes is unknown, although it did improve the F/B with K6NDV on
160m to 12dB.

Over the last few days I've checked the F/B on sky wave signals with F/B
as high as 36dB or better on 160, 80 and 40m.  It was strange that the
F/B on two stations in QSO with each other on 160m in Arizona varied from
about one S-unit for one station to six or seven S-units for the other.

This all has been with my 160m and 80m shunt feeds on my towers
completely detuned.  When the shunt feeds are tuned properly, the Pennant
F/B deteriorates to zilch on those two bands.  The Pennants are about 70'
from one tower and 22' from the other.  When detuned, the tower
structures are 1/4-wave resonant at about 2100 kHz and modeling still
shows a very noticeable affect, although nowhere near as bad as when the
towers are tuned.

I plan to retune the towers tomorrow so as not to miss out on the DX, hi.

73, de Earl, K6SE

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