Microwave Experiments - PowerPoint PPT Presentation

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Microwave Experiments

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Measure the angle of maximum intensity. Using this angle and Snell's Law, calculate the index of refraction of the Prism ... Our source and receiver are polarized ... – PowerPoint PPT presentation

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Title: Microwave Experiments


1
Microwave Experiments
  • Fred, Geoff, Lise,and Phil

2
Intensity vs. Angle
S
Probe
3
Basic Optics
  • Reflection
  • Angles
  • Standing Waves
  • Speed of light cln (freq(x/nodes)2)
  • 10.5 .1 Ghz -gt 3.01E8.03E8 m/s (typical)

x
qI
qR
S
Probe Count Nodes in x
S
M
4
Intensity
  • Point Source I1/r2
  • Our Source I1/r

M
S
r
5
Refraction Through a Prism
  • Use prism
  • See handout for experiment diagram
  • Measure the angle of maximum intensity
  • Using this angle and Snells Law, calculate the
    index of refraction of the Prism
  • n 1.46

6
Polarization
Received Signal
Receiver Polarization
q
Source Polarization
  • Polarization Direction of E-field
  • Our source and receiver are polarized
  • Only projection of E onto polarization of
    receiver is detected Ereceived cos (q)
  • Intensity cos 2(q)

M
7
Interference
z
q
f
  • Path Difference
  • Wave is f(kx-wt)
  • Implies Phase Diff.
  • Dkd (2p/l) f (z/d)f sin(q)
  • Effect of D
  • Esin(kx-wt-.5 kd) sin(kx-wt.5 kd)
    2sin(kx-wt) cos(.5 kd)
  • IE2
  • I cos2(.5 kd) cos2(.5 k f sin(q))

d
q
dgtgtf -gt sin(q)-gttan(q) So d f (z/d)
d
8
Double Slit Interference
  • Diffraction Effects
  • Intensity from each source varies as sin2(a)/a2,
    where a.5 k w sin(q), wslit width
  • So I sin2(.5k sin(q) w) cos2(.5k sin(q) f) /(.5
    k sin(q) w)2
  • Prediction
  • Black Diffraction
  • Blue Diff. Interference

I
f 2 w
q
9
Double Slit Results
Mirror Extension
  • Results
  • Envelope and Interference
  • Limit of Resolution of Angle?

10
Single Slit Diffraction
  • Used various slit widths and measured intensity
    verses angle
  • sin(q) nl/a

Mirror Extension
a
11
Single Slit Diffraction
12
Lloyds Mirror
S
M
  • Premise
  • Two ways to reach detector
  • Off of mirror or straight line
  • Path difference implies interference
  • 2(Distance Between Maxima)l
  • Results
  • Wavelength
  • 2.5 .7 cm
  • c2.6E8 m/s .3E8 m/s

13
Fabry-Perot Interferometer
  • Changing the interference pattern between two
    partial reflectors allows us to measure the
    wavelength.
  • See handout for experiment diagram
  • (d2 d1)/M l
  • We measured l 2.62 0.1 and
  • l 3 0.1

14
Michelson Interferometer
  • Setup
  • Beam Splitter
  • Path Difference-gtInterference
  • Results
  • Wavelength

S
M
15
Fiber Optics
  • Using tube filled with styrene pellets, we
    noticed higher transmission levels
  • Although very sensitive to positioning, the
    signal was rather constant with different
    curvatures

16
Bragg Diffraction
  • Braggs law give us a way to measure distances
    between crystal planes
  • d sin q n l/2 where d is the distance between
    crystal planes

http//www.physics.sfsu.edu/bland/courses/490/lab
s/d2/braggthy.html
17
(No Transcript)
18
Frustrated Total Internal Reflection
2
1
S
  • Setup
  • Is there any transmission to 2?

19
Lenses
S
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