3B SCIENTIFIC PHYSICS U8493600-230 Mode D'emploi page 9

•
Use switch (7) to send the modulator to "INT".
The microwave signal emitted is modulated with a
square wave. The modulation frequency can be lis-
tened to by means of the built-in speaker.
The amplified receiver signal can be output from
sockets (2) and (3) in the form of a DC signal (once
modulation has been turned off), in the form of a
square wave (with internal modulation) or in the
form of low frequency signal (external modulation).
Modulation is deactivated when switch (7) is in its
centre position. DC signals proportional to the level
and gain are output from sockets (3) and (4).
6.1 Straight-line propagation of microwaves
•
Set up the transmitter (11) and receiver (19)
facing one another.
•
With the receiver off the rail, move it in a
plane perpendicular to the rail.
The optimum reception is when the horns are
directly facing one another.
Conclusion: microwaves propagate in a straight
line (in uniform media or in a vacuum).
6.2 Penetration
•
Attach the dry absorption plate (14) (electrical
insulator) to the plate holder between the
transmitter and receiver.
•
Set the amplification (9) to a medium level.
Conclusion: microwaves can penetrate insulators,
as demonstrated by the reception of a signal.
6.3 Screening and absorption
•
Place the reflection plate (14) (electrical con-
ductor) between the transmitter and receiver.
•
Set the amplification to a low level.
Conclusion: electrical conductors can screen out
microwaves (metal plates), as demonstrated by the
fact that no signal is received.
•
Attach the absorption plate to the plate holder
having dampened both sides first.
Conclusion: When penetrating materials of low
conductivity, the microwaves are attenuated, i.e.
partially absorbed.
This can, for example, be displayed using an instru-
ment with a dial (e.g. AM50 analog multimeter
1003073/U17450).
If switch (7) is set to "EXT" low frequency signals (e.g.
from an MP3 player) can be input to sockets (5) and
(6) and played on the internal speaker inside the
basic apparatus. (jack to 4-mm socket adapter nee-
ded).
Information is sent via the microwave signal from
the transmitter to the receiver.
6. Sample experiments
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