Electromagnetic Spectrum - California State University, Los Angeles
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Transcript Electromagnetic Spectrum - California State University, Los Angeles
Electromagnetic Radiation
& Satellites
Antenna Design
Pete Arvedson
California Science Conference
October 26, 2013
Hosted by Satellite Educators Association
Lesson plan development supported by a grant from NOAA-CREST West
Session Objectives
Relate wavelength and frequency
Construct 1/10th scale model wave
Calculate antenna length
Apply to 5-element Yagi antenna design
Build 1/10th scale antenna
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Antenna Design - 2
Solar radiation
reaches Earth
surface
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Antenna Design - 3
Surface features
reflect solar
radiation to
remote sensors
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Antenna Design - 4
Satellite sends
radio signal from
remote sensors to
Earth station
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Wave Properties
wavelength, λ (meters)
amplitude
crest
trough
How many waves pass a point each second
= frequency,
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ν (1/sec or Hertz)
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Electromagnetic Spectrum
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Wave Properties
c
λν
c = λν
λ=c/ν
ν=c/λ
c = speed of light = 299,792,458 m/s
-in vacuum ~ 300 x 106 m/s
-in metal = 280.225 x 106 m/s
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Wavelength from Frequency
POES WEFAX frequency = 137.50 MHz
λ=c/ν
6
300 x 10 m/s
2.18m
λ =
6
137.5x 10 Hz
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Build Wave Model: 1/10 Scale
wavelength: λ = 2.18 m
1/
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scale model wave:
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λ = 21.8 cm
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Antenna Size – First Look
EMR energy resonates in antenna metal
wire producing current
Antenna length should match radio signal
wavelength
Wavelength for 137.5MHz = 2.18 m
½ or
¼ wavelength is best!
2.18 / 2 = 1.09 m
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Antenna Size - Actual
velocityin vacuum 300 x 106 m/s
λ
6
frequency
137.5x 10 Hz
2.182 m
velocityin metal 280.225x 106 m/s
λ
6
frequency
137.5x 10 Hz
2.038 m
½ wavelength = 1.019 m
1/
10
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scale model antenna length =
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10.19 cm
Antenna Design - 12
Yagi Antenna
1926 Hidetsugu Yagi & Sintaro Uda
Tohoku Imperial University, Japan
Driven element; parasitic directors & reflector
Highly directional & wavelength selective
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Brent Stirton, http://ngm.nationalgeographic.com
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Design Your Antenna
3.0 cm
87.4 cm
8.74 cm
92.0 cm
9.20 cm
96.8 cm
9.68 cm
18.3 cm
10.19 cm
4.1 cm
112.1 cm
11.21 cm
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Extension
Build scale models other antenna types
Calculate antenna length for 1693 MHz
Build several real antennas & determine
which is best for satellite reception
Compare/Contrast crossed Yagi with QHA
Build chicken wire parabolic reflector
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CA Science Standards
Grades 9-12: Physics
4. Waves have characteristic properties that do
not depend on the type of wave (a, c, e)
5. Electric and magnetic phenomena are related
and have many practical applications (e, f, h)
Grades 9-12: I & E
1. Scientific progress is made by asking
meaningful questions and conducting careful
investigations (a, d, g)
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Contact Information
Pete Arvedson - [email protected]
Check out lesson plans in Satellite Educators Association
(SEA) monthly Newsletter…
http://www.SatEd.org
More opportunities to involve students doing research:
SEA’s M.Y. S.P.A.C.E.* Program - an international high
school collaborative environmental research program
using satellite-based data…
http://www.calstatela.edu/programs/crest/
* (Multinational Youth Studying Practical Applications of Climatic Events)
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