Radials on my screwdriver
 

If I decide to put my screwdriver to use (I no longer mobile) up in the
attic or on the roof, would radials about 8ft. be as good or better than
a capacitave top hat?
Perhaps the large hats like DXEngineering has? That 8ft. comes from the
old timers that say the radials should be as long as the physical
height, I don't know 'nuff antenna math to really figure it out.

Butch KF5DE

Two different animals Butch, if you have a perfect ground under a short
antenna, adding a capacity hat improves the antenna. With less than perfect
it still helps. Reg has a program you can download that will show you the
gains in efficiency at various hat sizes.

Mounted in the attic, I would put resonant radials for the higher bands
where you have room. Once you have put the best counterpoise you can, add
the capacity hat to improve efficiency.

It is always a trade off, if the hat is too big you won't be able to work
10. With the current direction of the sun spot cycle, I would try to get as
efficient as I could for 20 and below. I would be inclined to string 3
wires, 2 cross corner and 1 end to end of the attic. Tie them together in
the center and run a wire from the junction to the point you normally put
the whip on the screwdriver.

Good luck and let us know what you did and your success with it.

73 Fred W4JLE


"Butch Magee" wrote in message
...
If I decide to put my screwdriver to use (I no longer mobile) up in the
attic or on the roof, would radials about 8ft. be as good or better than
a capacitave top hat?
Perhaps the large hats like DXEngineering has? That 8ft. comes from the
old timers that say the radials should be as long as the physical
height, I don't know 'nuff antenna math to really figure it out.

Butch KF5DE

Being the antenna is elevated, I wouldn't expect 8 ft
radials to work worth a hoot, except for 10m.
They need to be resonant. The "same height as
radiator, for usable performance" doesn't really apply
to elevated radials, that need to be resonant. Only
ground mount, will that work ok. Yes, a hat will always
help, but I would just string it with cheap wire, if it's
hidden away in an attic. If on a roof, you could hang
sloping top loading wires, that sloped towards some tie
off point. Or you could use a fancier hat setup....More
$$$ though. :( BTW....In theory, it should be possible to
use loaded radials...Or maybe a 2nd loaded element to
complete the antenna as a psuedo loaded dipole. ?? MK

Gud morning Mark Keith, You guys could make my life considerably less
complicated if you would just come up with an FM antenna design for my
screwdriver,...FM, that is Flippin Magic. Thats all I'm asking for
here, magic!
Kidding aside here, I think on the roof is out the question now. My
favorite wife just won't go with radials all over the roof.

I don't understand the "sloping top loading wires, that sloped towards
some tie point". You have a picture of something like this? It would
sure help me out trying to visualize this thing. You are trying to
educate a slow learning hombre down here,..pics go a long way. :-[

I can't tell you how much I appreciate you helping me out with this
little project. You have a good day and God bless.

Butch Magee KF5DE



wrote:

Being the antenna is elevated, I wouldn't expect 8 ft
radials to work worth a hoot, except for 10m.
They need to be resonant. The "same height as
radiator, for usable performance" doesn't really apply
to elevated radials, that need to be resonant. Only
ground mount, will that work ok. Yes, a hat will always
help, but I would just string it with cheap wire, if it's
hidden away in an attic. If on a roof, you could hang
sloping top loading wires, that sloped towards some tie
off point. Or you could use a fancier hat setup....More
$$$ though. :( BTW....In theory, it should be possible to
use loaded radials...Or maybe a 2nd loaded element to
complete the antenna as a psuedo loaded dipole. ?? MK

I don't understand the "sloping top loading wires, that sloped towards
some tie point". You have a picture of something like this?.......

Just visualize a upside down ground plane, with the radials on top,
instead of the bottom. That's about what it would look like. They could
slope a bit, and I don't think it would hurt too much. I think it will
be more
effective as a hat, if you can connect the ends of the wires to make a
outer
loop. But you don't have to do that. If you had it in the attic, and
the roof/
rafters were all wood, with no metal, you could have the tip of the
antenna
near the roof/rafters, and just run the hat wires along the rafters.
But ya still have to worry about those ground radials....:(...
It might be easier to make some kind of attic dipole, or loaded dipole,

using two elements back to back. That type antenna requires no
radials.
I have two attic antennas myself...One is a 2 m ground plane, hung from
the rafters, and the other is a 40m dipole, that is fed with 300 ohm
line
to my tuner. It will work 40-10 ok...It's kinda of a backup I can use
if the lightning is so bad in the area, that I don't want my regular
outside
antennas connected. I even unhook it, if it gets real close.
MK