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Author Topic: Yaesu ATAS-120A tuning dilemma  (Read 6545 times)
W5WSS
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Posts: 1723




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« Reply #15 on: September 20, 2013, 07:39:25 AM »

Hello, two tuned 1/4 wave elevated radials traveling in opposite directions relative to the center where the feed line shield connects to drive both the radials/sets of two per band and the center conductor connects to the vertical radiating element will work. This is center feed.

The tripod should be DE emphasized as part of the shield antenna circuit (relative to the driven radials) and the radials should be isolated from a dc ground connection out at the terminating dead end they should be isolated from a dc path to ground using non conductive anchors to hold them taught.

The definition of this  type of antenna is hybrid vertical dipole where tuned dc isolated pairs of radials represent a split half into equal and opposite oriented direction for system balance.

The tripod need not be modified to be actively involved in deliberate driven shield connection and should better simply serve as an inactive radiating support structure.

There are three types of vertical systems relative to radials:

The Ground mounted vertical

The Ground Plane isolated elevated tuned 1/4 wave radials horizontally oriented and non radiating radials.

The hybrid vertical dipole using sloped tuned pairs of 2,4 equally positioned in opposite direction and isolated from dc ground termination. they are Radiating radials because of 45 degree angled positioning relative to the vertical radiator and should be viewed as the second half of the dipole that is being utilized as a vertically oriented vertically radiating antenna system.
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NO9E
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Posts: 401




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« Reply #16 on: September 23, 2013, 12:56:33 PM »

ATAS120 is a pretty reasonable mobile antenna. Even with lap mount.

It is IMHO a disaster antenna for portable operations unless on a metal roof. Any vertical wire to a tree or on a  thin fiberglass pole with some counterpoises and a tuner will likely beat it by a many db.   

Ignacy, NO9E
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