PASCO WA-9316A Complete Microwave Optics System - Manual (Page 12)

Experiment Guide Experiment 3: Standing Waves – Measuring Wavelength
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•  = _________________________.
5. Repeat your measurements and recalculate l.
• Initial Position of Receiver = _________________________.
• Minima Traversed = _________________________.
• Final Receiver Position = _________________________.
•  = _________________________.
Question
Use the relationship velocity =  to calculate the frequency, , of the microwave signal (assuming velocity of propagation in
air is 3 x 10
8
m/s).
(  = the expected frequency of the microwave radiation - 10.525 GHz).
NOTE: This experiment can also be performed using the PASCO Microwave Detector Probe (Model ME-9319A), as
described in Method B below. Method A can be used for those without a probe. However, in Method A, the wavelength,
 can
not be measured directly from the standing wave pattern. In Method B, the wavelength can be measured directly from the
standing wave pattern.
Method B
1. Arrange the equipment as shown in Fig-
ure 3.1.
2. Plug the Detector Probe into the
EXTERNAL ANTENNA connector on
the Receiver. Face the Receiver horn
directly away from the Transmitter so
that none of the microwave signal
enters the horn. Adjust the Receiver
controls as needed to get a strong meter
reading.
3. Slide the Probe along the Goniometer
arm (no more than a centimeter or two)
until the meter shows a maximum read-
ing. Then slide the Reflector (again, no more than a centimeter or two) to find a maximum meter reading. Continue mak-
ing slight adjustments to the Probe and Reflector positions until the meter reading is as high as possible.
4. Now find a node of the standing wave pattern by adjusting the Probe until the meter reading is a minimum. Record the
Probe Position along the metric scale on the Goniometer arm.
• Initial Probe Position = _____________________.
5. While watching the meter, slide the Probe along the Goniometer arm until the Probe has passed through at least 10
antinodes and returned to a node. Record the new position of the Probe and the number of antinodes that were traversed.
• Antinodes Traversed= __________________________.
• Final Probe Position = _________________________.
6. Use your data to calculate , the wavelength of the microwave radiation.
 =_________________________.
7. Repeat your measurements and recalculate .
• Initial Probe Position =_________________________.
• Antinodes Traversed =_________________________.
Detector
Probe
Reflector Receiver
Figure 3.2: Equipment Setup