The DX Engineering and Bouvet Island teams have worked together to design an
efficient 90 foot top loaded 160 meter vertical antenna that can be
installed quickly and safely on Bouvet Island by the 3Y0Z team this January.
With a good radial system the difference in gain between a 120 ft (full
quarter wavelength) vertical and this custom 90 foot top loaded vertical is
less than 0.5 dB.
This vertical uses a custom designed heavy duty hinged pivot base with base
insulators to accommodate a 40 foot falling derrick 3 inch heavy duty pipe
for installation.
The vertical is base fed using two inductors to match to 50 ohms. The first
70 feet of the vertical is Universal Aluminum tower (12 inch face) and the
top 20 feet is 1.875 inch diameter aluminum tubing.
There are guys at 30, 50 and 70 feet. There are also three 30 foot top
loading wires attached to the top of the tubing that are tied to anchors 60
feet out from the base.
DXE is actually donating two of these vertical packages to the 3Y0Z team in
case one gets damaged (there are 300 storms per year on Bouvet).
More details on the construction and the final test raising plus VSWR
measurements are shown in the video filmed and produced (in 4K Ultra) by
Greg, W8WWV.
https://www.youtube.com/watch?v=bSw-0TjaUiU
73,
Tim K3LR
_________________
Topband Reflector Archives - http://www.contesting.com/_topband
|