80m dipole quick extension

published:

tags: [ #amateur radio, #antennas ]

When I made my electrically-shortened wire dipole for 80m band, I centered it for the SSB portion of the band (around 3.700 MHz).

Now that I've been learning and practicing my CW skills, I needed the wire dipole to work well also for the lower portion of the band where most of the CW activity is. But the workable bandwidth on these frequencies is pretty narrow and below 3.600 my FTDX10 couldn't tune it. Even if it could, this would not be very efficient.

Thus, I thought of a simple handy quick extension trick: extension wires with cable lug connectors:

  • 2 extension possibilities to gradually tune the resonant frequency down by simply attaching them to both of the dipole ends: 80m dipole extension

When not extended:

  • Center frequency: around 3.750
  • 3.700 to 3.810 SWR below 1:2
  • 3.650 to 3.840 SWR below 1:3 80m dipole end no extension 80m dipole center at 3756

Single extension:

  • Center frequency: around 3.630:
  • 3.580 to 3.672 SWR below 1:2
  • 3.540 to 3.700 SWR below 1:3 80m dipole single extension 80m dipole center at 3630

Double extension:

  • Center frequency: around 3.535:
  • 3.492 to 3.582 SWR below 1:2
  • 3.450 to 3.612 SWR below 1:3 80m dipole double extension 80m dipole center at 3535

The dipole is set up in an inverted vee config, both ends go towards the ground at each side of the garden, so it is very easy for me to attach or detach these extensions based on the need.

As you can see, with using these extensions I can now have SWR below or equal to 1:2 almost through the entire band.