The Hallo Field Day trap series has been designed so that it is possible to build a line of half-wave antennas for any band.
Field Day traps are parallel resonant circuits that reach the appropriate impedance during resonance to cause a break in the antenna length.
Thanks to this, we will achieve an effective multi-band antenna, with each band having the most effective length – half a wave.
How to use this trap? If you have two resonant traps, you can build a 40 – 20m dual band dipole antenna.
In the resonance traps, I used appropriate clamps so that you can freely tune your antenna from the SSB , e.g. to the CW or DIGI. This solution eliminates the antenna tuner and the losses it introduces into your antenna system. It is especially important when transmitting at low power.
Losses in resonance traps
The self-resonance of the traps causes the flow of large currents. Therefore, I set it outside the work band to minimize possible losses.
- High impedance frequency: 21mHz
- Power: 100W SSB CW, 50W DIGI
- Antenna tuning terminals
- Winding wire: copper 0.75
- Antenna wire holes: 1.5mm
- PCB dimensions: 70mm x 40mm
- Resonance traps protected with varnish