Re: Antenna link

From: Terry (tsanford_at_nf.sympatico.ca)
Date: 12/28/04 

Date: Tue, 28 Dec 2004 13:39:30 -0330

> 12.5 mm is 0.4921259 inches on this planet ...... snipped .........
>
Nope: Ignoring the banter. It's 4.9 inches!

At 2.4 gHz One Wavelength = 300/2400 = 0.125 metres = 12.5 centimetres

Centimetres!
(A typical 6" 8" doorway is roughly two metres or two hundred centimetres
high).
And one hundred centimetres is roughly 39.3 inches.
So 12.5/100 x 39.3 = 4.9 inches.

But the 'probe' that launches and receives the signal would presumably be
one quarter wavelength? To match the 50 ohm feed line?
So probe length (inside the can and hopefully at the dish focal point?)
would be 4.9/4 = 1.23 inches approx?????????

The dish being 'too small', having been designed for 10 gigahertz would have
only a portion of the capture area . It would therefore exhibit a 'loss' or
'lower gain' at 2.4 gHz? Possibly expressed in decibels?

    f w
m.hertz centimetres
 300 100 (One metre)
 600 50
1200 25
2400 12.5
4800 6.25
9600 ` 3.125

Here in Canada we are becoming pretty well bilingual in regard to metric or
non-metric.
We measure building materials both ways. Gasoline in litres and distances in
kilometres. Car engines in may countries have been measured in litres/ccs
for years! Radio wavelength which is inversely related to frequency has been
measured in metres almost from the word go.
I've never heard of radio station frequency or wavelength measured in feet
or miles?

Terry.

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