3B SCIENTIFIC PHYSICS U8493600-230 Mode D'emploi page 12

6.10 Polarisation
•
Set up the polarisation grating (18) in the
screen holder.
•
Check the reception when the polarisation
grating is aligned horizontally.
•
Check the reception when the polarisation
grating is aligned vertically.
Conclusion: Since in one state a signal is received
but when the grating is rotated 90° no signal
reaches the receiver, it can be demonstrated that
the horn antenna produces a field that oscillates in
one direction only, i.e. the output is polarised.
The experiment proves that the waves are trans-
verse.
If the transmitter and receiver are set up so that
one is vertical and one horizontal, no reception is
possible
If the polarisation grating introduced into the
beam and tilted by 45°, an attenuated signal is
received. The polarising plane is thus inclined.
6.11 Transmission of information
•
Set up the transmitter and receiver facing one
another.
•
With the receiver off the rail, move it in a
plane perpendicular to the rail.
•
Reception is best when the openings are facing
one another.
Using internal modulation (3 kHz signal) or exter-
nal modulation (e.g. sound from an MP3 player) it
is possible to transmit information.
Conclusion: microwaves (electro-magnetic waves)
can carry information.
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