,
Um, that's an aerial. Providing you can show your device lays within the power ratings of table 3.12 of
Snap! It was called GEC Traffic Automation when I was subcontracted to them from GEC Computers. Many years later, I was working back in the same building, and GEC Computers and GEC Traffic Automation had a bowling league each Monday evening, until the Traffic guys suddenly won the Pools, stuck up 2 fingers to their management, and left!
And "just electromagnetism" means that a time-varying current flowing in any wire loop _will_ create a radio emission, i.e. an E-M far field with its amplitude falling off as 1/distance. This follows from Maxwell's equations, as sure as eggs is eggs.
Sure, in an induction application like this it's likely to be the magnetic near field that is being used, this being much stronger near the coil, but falls off rapidly as 1/(distance)^3. The source oscillator and the coil/loop don't know that however, and happily radiate both components.
The ferrite rod aerial in any LW/MW radio and its predecessor the frame aerial used on some old valve sets are examples of the same principle in reverse - small current loop receives E-M radio field.
instance:
excellent! thanks for that link - that is EXACTLY what I am after - now hope I can build it!
Cheers to all
Jim
Boring Wood? I was there for just over 18 months in 1974-5. Thank God, I was head-hunted away.
Good for the Pool's winners!
R.
Yes.
It was probably about 1985 when I was subcontracted there, helping them out with communications between each traffic light controller and the central sequencing computers.
I think this was about 1993. They had just gone through a round of redundancies, where strangely, lots of engineers got fired, and no managers. They claimed that left them with more managers than people to manage. Then the engineers' Pools came up, and they took great delight in just quitting, already being very cheesed off with their management. After a month or so, all their kit just got dumped by the goods lift as rubbish, and I think that must have been the end of that group. In the piles of rubbish were loads of toughened glass faceplates for pedestrian crossings with the little red and green men on them, two of which have made very handy little cheese boards and amusing conversation pieces ever since (particularly the one in arabic).
Of course. Who decides where redundancies are needed?
Bit like MPs saying they only followed the rules for claiming allowances. And they ok'd those rules...
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