28 MHz Antenna Project – 10m Flowerpot Antenna

Since building a 6m coaxial dipole in January 2016 and later a 2m coaxial dipole in February 2018, I have often thought how a monoband half-wave vertical coaxial dipole would perform on 28 MHz. Summer is here in the southern hemisphere, therefore now is an excellent time to construct a 10m half-wave coaxial dipole for the upcoming summer Es.

Well, let’s make one and see how it performs.

Before you start please read the construction techniques found in the 6m post. (link above) Your telescopic pole should be made from a non-conductive material like fibreglass. Don’t use this antenna in combination with a carbon fibre pole. Carbon fibre or a composite graphite fibre pole will detune the resonant frequency.

Materials:

  • 13 metres of RG58AU/CU 50 ohm coax. I have included 5m to the radio, you can select a longer length as required.
  • Recycled 2.6 metre length of 18 gauge multi-strand copper wire (alternate to using the coax inner conductor)
  • 170 mm length of recycled 50 mm plastic pipe
  • 2 small cable ties to clamp the coax to the inside of the 50 mm pipe, top and bottom
  • Small section of kitchen cutting board
  • Recycled terminal block
  • 50 ohm RF connector of choice

Dimensions:

  • Top section 18 gauge wire: 2505 mm
  • Braid section of the coax: 2450 mm
  • LC choke: 24 turns, 120 mm long
  • Remaining 5 metres of coax to the radio or a length of your choice

VSWR

RigExpert AA-600 VSWR

Return Loss

RigExpert AA-600 Return Loss
28 MHz coaxial dipole assembly

Top anchor plate (slides over the top section of the telescopic pole)

Top anchor plate combined with a terminal block insert

On air action from Mt Stromlo 2 December 2022

28 MHz coaxial dipole antenna mounted on a 7m telescopic fibreglass squid pole
LC Choke 24 turns
LC Choke – 24 turns on 50 mm plastic pipe. Coil length is 120 mm.
28 MHz coaxial dipole antenna

VK1AD SOTA activator log from Mt Stromlo VK1/AC-043 – not too bad for a Friday afternoon and Saturday morning. VK4 stations are approximately 950 km NNE while the VK5 station is 1000 km west of VK1. My radio is an Icom IC-705 set to 8 watts output.

Map courtesy of SOTA Maps

Saturday morning I returned to Mt Stromlo with the anticipation of working sporadic E around mid day . The map indicates the antenna has a good omnidirectional radiation pattern working VK4, VK5, VK7 and ZL

Map courtesy of SOTA Maps

Enjoy constructing a 10m coaxial dipole antenna, known in some circles as the Flowerpot Antenna

Post Date: 2 December 2022

Last updated: 5 December 2022

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