Thread: Loading Coil Q
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Old March 25th 05, 08:07 PM
Cecil Moore
 
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Reg Edwards wrote:
I've never seen one near to, but I understand "screwdriver" type
mobile antennas are akin to long helicals specially at the lowest
operating frequency.


All of the screwdrivers with which I am familiar use a
3-6 foot straight bottom section. The 2 foot max coil is
approximately in the center with a 3-6 foot whip. The coil
goes in and out of the 3-6 foot bottom section for tuning.

Do you subscribe to the theory that a one foot long coil
radiates approximately the same RF as a one foot long
piece of wire? With any reasonable diameter of coil, the
resistance in that one foot long coil will be greater
than the resistance in one foot of wire. For instance,
the circumference of a coil may be one meter while the
turn spacing may be one centimeter. What size wire do
you need to compensate for that 100/1 ratio?
--
73, Cecil http://www.qsl.net/w5dxp

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