Experimental report 5Investigation of transmission of electromagnetic wave(microwave) môn Vật lý đại cương 2 | Học viện Công Nghệ Bưu Chính Viễn Thông

Experimental report 5
Investigation of transmission of electromagnetic wave (microwave)
I. Personal information verification of the instructor Name: Duong Duong Student ID: 20222829 Group: 2
II. Data processing and discussion
1. Investigation of straight-line propagation of microwaves: *Observation:
●When the receiver is aligned with the rail (the transmitter and receiver are
facing each other), the voltmeter shows the maximum value.
●When the receiver moves far from the rail (in a plane perpendicular to the
rail), the value of volt-meter decreases. *Conclusion:
●Microwave propagates best in straight line.
2. Investigation of penetration of microwaves: *Observation:
●When a dry absorption plate (electrical insulator) is put between transmitter
and receiver, the voltmeter slightly decreases. *Conclusion:
●Microwave can penetrate through the dry absorption plate.
Not all of the microwaves will penetrate through the dry absorption plate, a part
of them will be absorbed by the absorption plate.
3. Investigation of screening and absorption of microwaves: *Observation:
●When a reflection plate (electrical conductor) is put between transmitter and
receiver, the voltmeter shows a value that is very small compared to the
value when the absorb plate is absent. In this case, the voltmeter shows a value approximate 0. *Conclusion:
●Most microwaves will not go through the reflection plate.
4. Investigation of reflection of microwaves: Reflector angle Incidence angle 30°59° 40°82° 50°101° 60°113°
●When the arrow is the bisector of 2 rails (the reflector angle is equal to the
incidence angle), the voltmeter shows maximum value.
●Microwave reflects best when perpendicular bisector of the reflection plate
is the bisector of an angle created by the transmitter and receiver.
●When the microwave reflects, the angle of incidence equals the angle of reflection.
5. Investigation of refraction of microwaves: *Observation:
●When the angle created by 2 rails is 85o, the voltmeter shows the maximum value.
●As turning the receiver to a different angle, the value of volt-meter decreases. *Conclusion:
●Microwave refracts best at the angle of 85o.
6. Investigation of diffraction of microwaves: *Observation:
When the single slit plane is put in the rail, the value on the voltmeter increases.
When the plate í between the probe and the transmitter, the value on the
voltmeter is approximate 0. When the probe is moved on the horizontal
plane, the value slightly increases. *Conclusion:
Microwaves have diffraction properties.
7. Investigation of interference of microwaves: *Observation:
●When the probe is moved parallel to the plate, the value on the voltmeter
oscillates. Number of maxima = 3.
●When the grating is aligned horizontally the value decreases slightly.
*Conclusion: Microwave has property of interference.
8. Investigation of polarization of microwaves: *Observation:
When the grating is aligned horizontally, the value on the voltmeter is slightly decreasing.
When the grating is aligned vertically, the value on the voltmeter is approx. zero.
When the grating is aligned at 45 o, the value on the voltmeter is higher than
vertical case, but lower than horizontal case. *Conclusion:
With vertical polarization grating, only the vertical wave can go through.
The receiver’s signal is big.
With horizontal polarization grating, only the horizontal wave can go
through. The receiver’s signal is very small (approximate to 0).
With 45o inclined polarization grating, a part of vertical wave and horizontal
wave can go through. The receiver’s signal is smaller than when we use
vertical polarization grating and bigger than when we use horizontal polarization grating.
9. Determining wavelength of standing waves: x1(mm) x2(m m ) d(mm) 122 157 15 151 167 16 194 210 16 412 427 15 415 466 15
*The wavelength of the microwave is defined as: 5
d=15∑ di=15.4(mm) i=1
λ=2×d=2×=30.8(mm) √5∑(d−di)2 i=1 ∆λ=∆d= 5=0.2(mm) Hence:
λ=λ+∆λ=30.8±0.2(mm)
*Then, the frequency of the microwave is:
f=cλ=3×108 30.8×10−3=9.7 10 × 9(Hz )
∆ f=f× √(∆λ )2=9.7 10 × 9× √ (0.2 )2=0.1 10 × 9(Hz ) λ 30.8 Hence:
f=f+∆ f= (9.7 0.1 ± )×109(Hz)