The extended
double ZEPP for 15m
This antenna is
capable of giving a gain of 3dB over a dipole. It its 2 half waves in phase with
extra length to
give the correct distance between the ends of the 2 half waves.
Parts required:
60 feet of either
copper or stranded antenna wire
2 egg insulators
1 dipole centre
(preferably the ribbon cable type)
length 300ohm
ribbon feeder to suit length to shack.
Fold the antenna
wire into two and cut leaving 2 X
30 feet lengths.
attach an egg
insulator to the two pieces of
wire.
Measure 28 feet
from the egg insulator and secure to the dipole centre, leaving a tail
to secure to the
300 ohm ribbon feeder.
You should now
have a 56 foot dipole antenna.
Now join the
ribbon feeder to the dipole making sure it is secure and wont flap and break
in the wind. If
possible fit the joint between the antenna and ribbon into a plastic box such as
a film canister
and fill it with epoxy resin to waterproof the joint.
This is very important.
Hoist the antenna
into the air as high as possible. Take the feeder back to a balanced ATU, such
as a "Z Match". You now have an antenna on 21Mhz with gain and it being similar to the dimensions of a G5RV,
give good results on other bands down to 40 metres.
See next Month
for a coaxial fed version.
With thanks to John D Heys G3BDQ and Practical wire
Antennas.