Re: [amsat-bb] 10m Turnstile or Loop for AO-7

["Edward R. Cole" <al7eb@xxxxxxxxxxxxx>]

At 08:14 AM 7/12/2003 -0500, Joel Black wrote:
>Just fiddling around with AO-7.  I know the 10m loop antenna would be easier
>to build and at 1/4 wavelength above ground (~8 ft) and 34ft. total length,
>it wouldn't be hard to receive really well on this.  On the other hand, the
>turnstile would require a phasing harness.  Right now, I'm using a
>multi-band HF vertical.  Just about anything would be better than what I
>have.
>
>Any opinions on the turnstile v. loop, or did I answer my own questions?
>
>Tnx es 73,
>
>Joel B. Black, W4JBB
>w4jbb@charter.net


Joel,

Not sure if it matters much:  but the turnstyle "crossed dipoles" will
exhibit circular polarization at high elevation angles and linear polarity
near the horizon.  The loop, though round is a linear polarity antenna and
will favor high elevations better than near the horizon if oriented
horizontal to earth.  If oriented vertical the loop is essentially equal to
a dipole in performance (maybe quieter in receiving in high noise
environs).  I am assuming you are talking a full-wavelength loop.

The muli-band vertical will work fairly well when near the horizon but not
well at high angles.  Vertical performance is highly dependent on the
quality of ground plane.  

I designed a 10m variation of the Texas "potato masher" phased square loops
of K5OE, but never got around to building it.  My version was in a "slighly
squashed dimond" configuration fed from the bottom vertex and mounted on a
30-foot fiberglass pole (wood would work too).  There were two ground
radials below for 3/8 WL mounting which produces the best pattern for
satellite use.  It is a NEC4WIN95 design.

73 - Ed AL7EB


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