For the hardcore nerds

[Apache]

Just finishing building this...



It's a sort of half way house between a stripline and a TEM antenna. have been experimenting with it for a year or so now, and have just finished fitting cooling fans and heatsinks to the load and matching resistors as the uncooled ones... er... had a short and spectacular life.

It's capable of generating fields between the two plates of around 200V/m (volts per metre) of RF energy between around 10kHz and 30MHz - the lower end being very difficult to do with conventional antennas because of the huge wavelength and low transfer efficiency.

Quite pleased with myself as very few test houses can achieve this

[puddlesurfer]

Well done mate - It's very cool, what is it?

[Apache]

Well done mate - It's very cool, what is it?

See first line under pic

[puddlesurfer]

See first line under pic

All is now clear (not) what would it be used for? Is it a very long distance CB aerial? Or does it allow you to pick up free dutch porn?

[gwh200]

I have no idea what that's for Andy...but it's spectacular. It's in the premier league of geeky, nerdiness. It's Ryan geek, playing away from home(phnarrrrrr),it itches my nerdy bone...wositfor?

[JUDWAK]

love it

[Apache]

Basically, several EMC standards require that equipment is subject to very high radiated fields. Whilst that's easy to do above around 30MHz via conventional antennae and brute force (lots of power), it just doesn't work efficiently at low frequencies unless you have a very large space and fecking huge antennae (think 10's of metres in every dimension). This isn't practical for obvious reasons - and some technical reasons.

This approach takes advantage of the field that develops between conductors, so basically it's a transmission line (a cable is a transmission line of sorts) with the conductors spread apart at a calculated rate, distance apart, width and length, then brought together again into a load / matching circuit.

The field still develops between the conductors, but the gap between them is big enough to place the equipment under test inside the field.

[flounderbout]

The field still develops between the conductors, but the gap between them is big enough to place the equipment under test inside the field.

Just so long as you don't get your "equipment" anywhere near that damn field... Fried nuts anyone?

[Apache]

Here it is in a screened room so that very thing doesn't happen!



And close ups of the loads for those who like that kind of thing

[slobodan]

Ahhh, A 'brown note' generator.

The MOD is catching on.

[JUDWAK]

you boff
what you going to do with it?
ya know the reason you made it is?
i no understand
in lamanns terms please keep it simple like me

[biosurf]

Blimey! That is fairly substantial!

[KERRSURF]

So what EMC gubbins get tested in it? Or is that top secret

[wishbone]

10kHz is in the audible spectrum - can you hear it ? If not how many volts would it take to make it audible ?

Rob.

[Apache]

Yes you can. You can hear the output tubes in the PA vibrating. Dont know if its audible from the antenna as we're not in the room when it's active - be a bit injurious to your health!

Back in the early radio days, near places like Droitwich, you could hear the programme demodulated by the chain link fences, cast iron down pipes and assorted other stuff. There's some really interesting stuff on the interweb if you're interested in big, dangerous machinery

Alan, you might be confusing EMC with ECM. But yes, ECM kit has to be tested to these standards, as does EVERY bit of military electronics.