I am preparing the next solar cycle and building a new antenna. YU7EF has designed fantastic
low temperature antennas. Why not to choose the
See below for the first results.
The antenna length is 15.5 meters. The aluminium boom is dubble: 50/46 mm and 45/41 mm inside on the full length.
The external tube length is 4.00/3.00/3.00/2.70 meters. The internal tube length is 2.70/3.00/3.00/4.00 meters. To avoid mechanical noise gease is applicated between the two tubes.
Two guys support the heavy antenna. The reference of the guy is Liros Magic D-PRO 3 mm (breaking load 900 daN, very low stretch and no water absorption).
Vibrations have destroyed so many tubing elements. For that reason I have decided to use 10 mm solid elements in a single piece. The weight is more important but it is much more heavy. No tappering nor bad connections.
The element bracked is in HDPE 300 natural. The best for HF, poor against UV. An alternative would be HDPE 500 black. The size is 160 x 50 x 12 mm.
The two dipole elements (still 10 mm solid) is isolated by 0.5 mm thin PTFE and Dow Corning 744 non-corrosive silicone sealant.
The H2000 Flex coax cable is choosen for his minimum radius and attenuation. An extra length (3/4 lambda) of coax is needed for the balun. The losses would be around 0.1 dB. A great advantage of that balun is the HF "stay" inside the coax... not like this. The disavantage is the frequency dependence and the velocity factor (not always as claimed) of the coax.
Dont use a small plate for that antenna. 300 X 150 X 10 mm aluminium would be strong enough. The plate is fixed to the mast by 4 clamps.
|Against side winds|
The length of the Glass fibre tube sold by Wimo is 2 meters long, 51mm diameter, wall thickness 8mm, weight 1,9 Kg/m. You can see the fixation details of the cables. The tube is closed by silicon to reduce the wind noise.
The dream is a reality. The results are as computed. Many thanks to Pop YU7EF.