[Lowfer] coil design validation

[Eric Smith]

Ok, Lyle ... thanks for your help.  That coil is going to be HUGE!  But 
I'm too far along to turn back now.  Looks like I'm going to need some 
more wire ...

I sure wish I had a better antenna so I could build a more reasonable 
coil.

Thanks again for your help,
Eric


On Sun, 16 Mar 2003, Lyle Koehler wrote:

> I can see only 4 radials in the picture. Adding the other radials and the
> inner wires to the model is messy, and I'll leave that as an exercise to the
> student :-) Seriously, closely spaced wires do not add much capacitance to
> the top hat, so a simpler "skeleton" model is usually adequate. If you
> actually need less inductance than the model predicts, that's fine. It's
> usually easier to tap down on the coil than to add turns.
> 
> Using the attached model, I come up with a required inductance of about 7.8
> mH. There will be some added capacitance because of the PVC pipe, but there
> is no easy way to estimate its effect.
> 
> Lyle
> 
> LowFER antenna with 4-radial top hat; variable height and hat diameter
> Ground Mounted
> 0.185 MHz
> 10 copper wires, feet
> Hmax = 34
> R = 4
> H = Hmax - R ; height of top hat
> HL = 1  ; height of loading coil above ground
> 
> 1   0  0  0   0  0  HL  #22  ; wire from base to coil
> 1   0  0  HL  0  0  H   #22 ; wire from coil to top hat
> 
> 1   0  0  H   R  0  H   .3" ; the next 4 wires are top hat radials
> 1   0  0  H   0  R  H   .3"
> 1   0  0  H  -R  0  H   .3"
> 1   0  0  H   0 -R  H   .3"
> 
> 1   R  0  H   0  R  H   #22 ; the next 4 wires are the top hat "skirt"
> 1   0  R  H  -R  0  H   #22
> 1  -R  0  H   0 -R  H   #22
> 1   0 -R  H   R  0  H   #22
> 
> 1 source
> Wire 1, end2
> 
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