g'day Brian,

Call frequency "f". Speed of light c = 3*10^8 metres/second. Wavelength =
c/f in metres. Quarter-wave antenna length then is c/4*f.

So, 406 MHz, call it 400 to simplify a bit. Wavelength = 3*10^8/400*10^6 =
3*10^8/4*10^8 = 0.75 metres. Quarter wave a bit under 20 cm, which would be
a bit under 8 inches old scale.

Cheers ... MikeW.

"brian whatcott" wrote in message
...
Dave Doe wrote:
...

You should - 'cos yer a bit out of date on the info thesedays. 406Mz
ELT's are manditory in most countries now. Also the monitoring
Cospass-Sarsat satellites will not find you with a 121.5Mz ELT as they
don't monitor it anyymore. You'd better hope for a nearby commercial
aircraft that's monitoring 121.5 - it's about your only chance now days.

The 406Mz system is also lots more accurate for position determination,
and, the beacons must be registered (registration of 121.5Mz devices was
never manditory).


Hi, User posting as Dave,

do you know how to relate emission frequency
to the length of a corresponding quarter wave whip?

Brian W