Saturday 15 May 2021

Stick to shore.

Time to test the Ampro stick-based antenna (price: not the £200 being asked for the commercial version!) at the beach last evening, passing a couple of hours whilst on taxi service for my daughter!

It's simple, and can take good winds.
 

Key to the success of this antenna is the requirement for 1/4 wave radials for the band of interest, and the raising of those radials off the ground - even if that is only a few centimetres.  With the radials on the ground, the matching is way off.  As soon as they leave the ground, matching becomes perfect.

It only takes a small stick to raise the radials enough for a perfect match.

This outing wasn't long enough to get a good WSPR dataset.  All I can say is that, with the tide a long way out, and no seawater-saturated ground beneath the antenna, the stick antenna was nevertheless achieving exactly the same SNR at the DX station, VE6JY, as my full wave delta back home - also a simple but much more complex to deploy antenna (think: elevated feedpoint and ~8m total height) than the Ampro - just ~2.5m tall.

Nice and warm, lying on the coastal grass.

 Overall, though, the stick wasn't anywhere near as good as the delta, as this map shows:


Over on a few bursts of FT4 - at about 3W - the stick is certainly not a dummy load:

And, of course, with any portable antenna, you get the distinct advantage of fresh air and wonderful views.  Even a little nibble on the very salty but refreshing sea kale, now in full bloom:

On the horizon is the lighthouse on the remote 'Skerries' - a name revealing of the area's Norse heritage.

Sea kale.  Delicious!

Below: 6m operation, the following afternoon, cut short due to oncoming heavy rain!  Initial assessment is that the Rapsberry Pi causes RFI at 50MHz, so will need some additional ferrites on cables.  I was getting to the Azores at -10dB on FT8, whereas my 2-ele quad was only managing -17dB at the time.  The radials are significantly less than 1/4 wave, being only about 1m each.



No comments: