[Lowfer] coil design validation
WE0H
[email protected]
Sun, 16 Mar 2003 11:52:22 -0600
It will still work. Put down plenty of ground radials or just use chicken
wire to keep the ground losses down a bit.
Mike>WE0H
http://www.we0h.us/lf
-----Original Message-----
From: [email protected] [mailto:[email protected]]
On Behalf Of Eric Smith
Sent: Sunday, March 16, 2003 11:41 AM
To: [email protected]
Subject: Re: [Lowfer] coil design validation
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