A trap dipole is a good choice if you only want operation on two or three bands and don't want to readjust an antenna coupler to change between them.
This video describes a trap dipole for 7 and 14 MHz with emphasis on the 1:1 current balun and 14 MHz trap.
Adding 80 metres: Loading coils can be added to provide 3.5 MHz capability with very little extra room required. My loading coils used 85 turns of 2mm (od) thin insulated wire closewound on a 55mm diameter pipe. There will be some interaction between the loading coil and the 7 MHz element. Add extra wire to bring it back into the 7 MHz band. The 3.5 MHz performance won't be as good as a full sized dipole, though some excellent contacts are still possible. The bandwidth will be narrow so I suggest using an antenna coupler at the transceiver end. Further ideas on the loading coil at: [ Ссылка ]
Contents
0:00 Introduction
0:23 Source information
0:48 1 to 1 balun
1:11 Making the balun
2:33 Making the traps
2:54 Testing/adjusting traps
5:32 Antenna construction
5:39 Final dimensions
5:42 Summary
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