[Lowfer] Antenna design idea question

[Bill Ashlock]

Mike,

There is a common misconception that a half wavelength or in fact a quarter wavelength of wire, when coiled, magically turns into a resonant antenna. This is totally incorrect! Resonance may occur with these lengths of wire but it is only then the resulting inductance just happens to match the capacitance to ground of the total antenna. A lowfer vertical must have a high Q loading coil to be effective... and we are talking a Q of at least 300 - and that takes careful design and construction practices. It has been shown through numerous experiments (the tedious efforts by Bill Bowers, for example) that the highest Q occurs when the length of the coil is 1/2 the diameter. A stretched-out coil that you suggest would have a Q much lower than this..... and the resulting antenna radiaton, also much lower, due to the RF losses in the coil

Bill

> Date: Sun, 27 Sep 2009 09:41:39 -0500
> From: k1eg at matrix-computers.com
> To: lowfer at mailman.qth.net
> Subject: [Lowfer] Antenna design idea question
> 
> Good morning all you Lowfer's out there.
> 
> I am trying to plan for an antenna for this winter and came up with an 
> idea based upon what a ham did for a shortened 80 meter vertical.  The 
> plan is as follows:  you take a 1/2 wavelength of wire and wind it on a 
> rod like a solenoid so that it is shortened considerably.  He claims 
> that it performs quite well.
> 
> What I have in mind is to take 4 lengths of PVC heavy wall pipe, 4", 3", 
> 2" and 1 1/2", and wind a 1/2 wavelength of wire over the 40' length.  I 
> would do this in 10' lengths and dope the windings in place to hold them 
> and then connect them together at each joint.  At the top I would add a 
> 10' diameter capacitor hat.  By using the different diameters this gives 
> me  anchor points for  Dacron guys.
> 
> My question is has anybody tried this?  Is it a feasible design idea 
> worth pursuing?  Any comments or feedback would be greatly appreciated.
> 
> 73,
> Mike
> K1EG
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