WICEN Vic: 6m & 2m Flower Pot Antenna Construction

[John & Bronwyn]

Last night on a ZOOM briefing for the upcoming Gippsland Rally, I was 
asked to provide details for a 'flower pot' antenna.

I thought this antenna may be of general interest to WICEN members, 
hence this email.

The 'flower pot' is a simple and cheap antenna to build using coax cable 
and easily obtainable PVC pipe sections.  It is rugged and easy to make, 
and performs extremely well, with a wide bandwidth, low SWR and a very 
good radiation pattern.  It is very repeatable to build.

In contrast most commercial mobile whips don't perform well when pole 
mounted for portable operation, they usually suffer from poor SWR and/or 
poor radiation pattern.  There are some exceptions, but in my experience 
they are in the minority.

The 6m 'flower pot' is especially useful, there are not many antennas 
available / suitable for portable operation on this band.

More information in the attached file.

If you need to use different materials, the dimensions of the top and 
bottom radiator sections probably won't be affected much.  But the 
dimensions of the choke coil are critical.

To design a different coil, you will need to use the calculator here:   
https://hamwaves.com/inductance/en/index.html#input    For a coil made 
of close-wound RG58, use a turn spacing of 5mm and a wire diameter of 
4mm.  The coil self-resonant frequency is at the bottom of the 'Results' 
section.   The choke coil must be self-resonant about 3% to 4% below the 
operating frequency.


Cheers,   John VK3ZRX
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