OK, the term Bridge in the title has nothing to do with SWR bridges or any other type of conventional bridge used in the shack.

This is an antenna design used for tuning up a bridge, or railings, or a pushbike frame etc.

It is just a bit of fun, easy to build and fun to use.  You definitely need an antenna matching gizmo though (a tuner in other words)

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I’ve put it all in a fried rice container left over from my last takeaway.

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Basically it is a home brew 4:1 Balun.  Hot out the top and counterpoise out the bottom.

The antenna lead is about 10ft long and is attached to the screw on the cutting wheel of a cheap pipe cutter.  The counterpoise wire, with a croc clip on the end, is about 25ft long and is deployed as needed (rolled up at the end it’s blind to the RF and can therefore be used to improve SWR matching on each band).  There’s 6ft of RG58/U coax terminating in a PL259 plug which goes to the tuner/matcher.
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You clamp the pipe cutter onto your chosen wierd object.  If it has a lot of paint on it, you can rotate the cutter slightly to cut down to the metal.  Don’t do this where it might prove destructive or dangerous, and if you do cut deep, some clear varnish in a small bottle brushed on afterwards will help prevent rusting.

So you clamp onto the bridge, set it up and try and get the SWR down to a managable level.  Once you get that far, call CQ.
Success is if you get a QSO somewhere.

 

 

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You could also just use the Balun for a conventional wire antenna, or a dipole as well, or make it a 9:1 Unun and you might get away without the counterpoise.  You could certainly use it with an EFHW antenna.
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It all packs away nice and neat in it’s little plastic box.

Go on, I know I’ve piqued your curiosity.  Try it and see if you can tune up something completely unusual.  Shopping trolly maybe?

Eric G1SLP.