This is an adjustable resonant dipole for HF. It can be manually
adjusted to any frequency from 3.5MHz to 30MHz by mens of measuring tape
rolls. With 50 meter tapes it can be adjusted down to 1.8MHz.
Feeding point has two measuring tapes, locks for the cranks and
a choke balun (4 turns on Fair-Rite 2631103002). All parts are installed on
a plastic sheet eg 5mm thick Polycarbonate sheet 270mm x 220mm.
Tape ends look like this. The cranking increment is abt 20cm per turn. The measuring tapes are from temu.com abt 10€ each. Available lengths are 20m, 30, and 50m. The tape enclosure and the tape material is some unknown ferromagnetic metal. Most probably the material will corrode in long time use, thus this antenna is mainly recommended for field-day operation or other temporary use. 
It is recommended to hang the feeding point up because it weights 1kg and install the antenna tape wires eg as inverted-V. 
This antenna can be adjusted even to 6 meter, but the cranking increment is a bit coarse. SWR example on 6 meter with a miniVNA PRO analyzer |
Update 2024-10-17 OH7SV
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