This dipole is ideal when there is not much space available to install a full lenght dipole for this band. It is only 10 meters long and it's a good compromise that allows you to work 40 meter band.
List of material:
- electrical cable 1,5 mm²;
- two 40mm outer diameter PVC pipes, 16cm long.
Drill a 3mm hole on the PVC support at a distance of one centimeter from the edge. Insert the electrical cable into the hole you just made and pull out three meters. This will be the central part of the dipole.
Wind 49 turns on the PVC tube, make a 3mm hole at the end of the winding and insert the rest of the cable. Measure two meters of electrical cable from the end of the winding and cut (leave an extra 10cm for calibration). Half of the dipole is finished, now do the same for the other half.
If you prefer, you can cover the spool with tape or heat shrink. If you fix the dipole on two fishing rods 5 meters long each, you will have a compact and lightweight rotary dipole.
The loading coil fixed on the fishing rod
Central support made with square aluminum tube 15X15 mm and antenna bracket
The use of a choke balun is recommended, as always, to match the (unbalanced) coaxial cable with the (balanced) dipole and to prevent the radio frequency come back to the braid. The bandwidth referred to an SWR of 2:1 is about 50 KHz. The use of an antenna tuner is essential if you want to use both cw and ssb.
73 and good DX