Testing a 2m Inflatable Emergency Antenna

Earlier in the year, Andy @MM0FMF got in touch. The SOTA MT had received a few antennas of a novel design, for testing purposes. Would I like to put one through it’s paces?

Fast-forward to early December, Andy and I met up, failed to erect the antenna due to a lost or forgotten adaptor, and so it came up the road with me - untried.

On Wednesday, I had the opportunity to nip out and give it a go. Craiglich GM/ES-068 can be put on the air within 40 minutes of leaving the house and is an ideal summit for testing stuff, so off I went.

I won’t say too much about the antenna here, as that is all in the video. All I’ll say is, it was a still December afternoon, with superb clear air. I could see snow capped Cairngorm summits over 70km away. The pics that follow, hopefully potray the serenity. Once I’d completed the test and disassembled everything, I lingered for some time, soaking in the atmosphere. One of those days where I just didn’t want to come down.


ready for the test


Lochnagar to Morven


descending


Mount Keen (right)


The video is here
https://youtu.be/H5nZlKUhV6M

And…
…thanks to Bill GM0NRT, Simon @GM4JXP and Alex @GM5ALX for making themselves available.

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I watched the video earlier Fraser, thanks for doing these videos.

I was trying to remember the story behind the inflatable antennas and piece it together. Interesting that they’re branded as Shakespeare these days. A bit of help from Google led me to Scottish based company Air Antennas, run by Tom GM3HNN. Air Antennas rebranded to RadioGeeks and ran for a couple of years and then it seems to have stopped trading. Comparing the RadioGeeks offerings and the Shakespeare antenna in your video, they’re definitely related.

73, Colin

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On the picture it looks like there is a fibre class pole up to the highest point. That kind of defies the idea of the inflation element replacing the mast.

Or maybe I did not see it properly?

But great scenery up there! :grinning:

73 Joe

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Yes there is. The aim was to see the effect of wind loading on a mast.

There was no wind. :see_no_evil:

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You are, of course, correct Colin. They have been around for a while. Someone commented that there was also an HF version available from Radio Geeks. Sadly they are no longer trading.

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There was someone I used to work on 2m when activating who had some sort of inflatable antenna he used when out portable. I can’t remember his call and I don’t think I’ve spoken to him for a while.

From his description, I thought his was one that you pumped up with a bike pump and was 5-6m tall and achored to the ground? Maybe it was a different antenna, or maybe I got my polarisation crossed.

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Hi Fraser,
Thank you for the report. I wondered about one of these as an emergency antenna for the boat.
Sorry we missed you on Wednesday but we were coming down from a similarly beautiful day on White Coomb by the time you were on air.
Hope you feel better soon.
Andy
MM7MOX

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Hi Fraser @MM0EFI ,

An interesting review, thanks. They appear to be available for a bit less than £100 now (see Shakespeare Galaxy INFL8 Inflatable Marine VHF Antenna 818-infl8 j160224) but still substantially more than the SlimJim option.

How long can you keep it up with the CO2 canister? I was looking at CO2 for my mountain bike tyres, but I’ve read that it seeps out overnight, so you have to use a manual pump anyway. Is this similar, or does it retain the gas for longer?

73, Simon

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The gas cannister is totally unnecessary. It inflates fully in seconds just by blowing it up manually - much quicker than a party balloon!

Yes, but it needs to be supported at the top if inflated manually. Using the gas vastly increases rigidity meaning it can be supported at the base only.

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I don’t know. I’ll inflate it tonight and see how it lasts.

Looks like it pays to shop around!

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If it is supported at the top, is there any advantage in inflating it at all?

I enjoyed the video, and agree with your assessment for SOTA use.

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If you fill it with helium it will automatically telescope your mast up and you can use the spare gas as type of speech processor.

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Or, adding more to that 5.5-metre length of coax, you could actually “fly” the antenna (if it’s not too windy)!

73 Ed.

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Geoff GM4WHA using Colin the Caterpillar inflatable antenna on Castle Crag LDW-214 it worked well on a back to back test with a flower pot antenna and Jpole

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