- 1:1 Air BALUN (NonFerrite) -
- Technical data -
This balun is normaly used with broad-band antennas,- where gamma-match or other narrow-band matching is not sutable. I use this baluna whith logo-periodic yagi antennas.
Impedance ratio........... 1:1 Frequency range...... 3-30 MHz Power handeling........... 2KW- Making the balun -
Principle - The coils on an air balun is not different from an Ferrite-balun, in the layout above you see the principle. Two coils (Yellow & red) is used as straight thru-feed, one for center conductor an the other for the sheild conductor, they are connected directly to each dipole half, The blue coil is used for reversed 'pick-up' and balances the dipole connections.
The Air-balun is made on a plastic 'Nonconducting' core,- Use a pice of plastic tubing about 25mm in diameter and about 66mm long. Drill tree 2mm holes,- slightly in diagonal in one end, whith about 5mm distance. drill tree 2mm holes in the same manner in the other end of the tube,- distance between the two hole-rows is 49mm.
Hint! It is best to make one coil at the time, dont trye to put al tree on the core at once.
Closeup on test setup
Frequency response using mini-vna
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