| W8JK
wire antenna
By Owen
Quarles <k1oj@swbell.net>
For optimum performance, the antenna should be erected horizontally
a minimum of 1/2 wavelength above ground.
When fed in the center, the antenna produces a bi-directional
pattern. The antenna may be made directional by attaching the
feed to one of the dipoles.The pattern will be directed towards
the 'other' dipole.
Connecting a string the length of 'B' between the ends of the
dipoles will help keep the spacing of the wires uniform.
Here is a rough diagram and the calculated measurements
I used:
____________________________________
A | | A
| |
| | <--450 ohm
| | ladder line
| | length 'B'
| |
\ /
X <--HALF TWIST
/ \ (180 DEG)
| |
| |
| |
| |
| |
________________| |________________
A A
20m A = 29.4ft B = 8.46ft
40m A = 58.7ft B = 16.9ft
80m A = 134.9ft B = 38.9ft
'B' is
an electrical 1/8 wavelength with a 1/2 twist between dipoles.
Feed is connected halfway between dipoles with twinlead or balun
and coax.
I used random lengths of 450 ohm line to feed these antennas and
had very good results with them.
(Editorial note: While the given values are for the Ham
bands, this antenna works great as a receiving antenna on other
bands as well, after dimensions have been adjusted)
Originally
posted on the Low Power Amateur Radio Discussion mailing list, March
2, 1997.
|
antennX 