If the capacity hat is at the bottom, what will then be at the top? The
counterpoise??
Yup.
What were you intending to put at the bottom of the "non-inverted"
version?
Radials, or just a ground rod?
Ground is lousy in Tucson whe
1) There is sand all over the place.
2) I'm on the second floor so my ground wire would radiate anyway.
3) I can't be sure of building grounds.
4) I can't bury my radials. Best to hide them in plain sight as innocent
SWL wires of #30 Kynar, invisible beyond 5 feet.
Therefore, a counterpoise makes better sense for me. Basically:
___
/ \ Birdhouse hides
feedpoint.
| o |
---------------=====--------------- 1/4 Lambda radials disguised as
invisible dipole.
O
O
O Helical wound
around 15 foot "support pole"
O for birdhouse.
O
O
O
-------- Capacity hat buried
in the sand.
Is the intended design a ground-plane type vertical (1/4 wave -or rather a
shortened 1/4 wave), or a di-pole (1/2 wave or rather a shortened 1/2
wave -
center or end fed) type?
The former.
It would seem to me that the bird house could be a pretty good "capacity
hat" as it would have quite a bit of capacitance to the universe, being a
pretty good volume of conductive material (since you would make sure it is
conductive, that is). Also, I can easily see a "squirrel baffle" right
below the bird house which, being made of metal, makes a pretty good
addition to the "Bird hat".
I understand. Fortunately, no squirrels, just pigeons.
..Now, the question is, how much de-tuning will the bigger birds have
??....
Stand-by fellas. I have to go out and chase the owl off my antenna to get
the antenna tuned back to the top of the band.
I doubt for QRP it is going to matter much
I'm more interested in how my radiation pattern is going to be affected
by inverting the vertical, assuming that there would be effectively no
conductive ground below the capacity hat.
The Eternal Squire
--
Steve N, K,9;d, c. i My email has no u's.
"The Eternal Squire" wrote in message
...
Hi all,
My wife wants to put up a birdfeeder and I want to put up a hidden
antenna.
[...snip...]
My intention is to put the birdfeeder on a dowel rod which I have wound
with
#30 white wire and spraypainted with white paint. The dowel rod would
be
15-20 feet tall, so a helical for 10-80 meters might make a lot of
sense.
Here's the big question: how badly would it hurt the helical's
performance
to install it "upside down"? ....
The Eternal Squire
---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (
http://www.grisoft.com).
Version: 6.0.564 / Virus Database: 356 - Release Date: 1/19/04