Electromagnetic Spectrum - California State University, Los Angeles

Report
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
Satellite Educators Association
California Science Conference 2013
Antenna Design - 2

Solar radiation
reaches Earth
surface
Satellite Educators Association
California Science Conference 2013
Antenna Design - 3


Surface features
reflect solar
radiation to
remote sensors
Satellite Educators Association
California Science Conference 2013
Antenna Design - 4



Satellite sends
radio signal from
remote sensors to
Earth station
Satellite Educators Association
California Science Conference 2013
Antenna Design - 5
Wave Properties
wavelength, λ (meters)
amplitude
crest
trough
How many waves pass a point each second
= frequency,
Satellite Educators Association
ν (1/sec or Hertz)
California Science Conference 2013
Antenna Design - 6
Electromagnetic Spectrum
Satellite Educators Association
California Science Conference 2013
Antenna Design - 7
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
Satellite Educators Association
California Science Conference 2013
Antenna Design - 8
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
Satellite Educators Association
California Science Conference 2013
Antenna Design - 9
Build Wave Model: 1/10 Scale
wavelength: λ = 2.18 m
1/
Satellite Educators Association
10
scale model wave:
California Science Conference 2013
λ = 21.8 cm
Antenna Design - 10
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
Satellite Educators Association
California Science Conference 2013
Antenna Design - 11
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
Satellite Educators Association
scale model antenna length =
California Science Conference 2013
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
Satellite Educators Association
California Science Conference 2013
Antenna Design - 13
Brent Stirton, http://ngm.nationalgeographic.com
Satellite Educators Association
California Science Conference 2013
Antenna Design - 14
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
Satellite Educators Association
California Science Conference 2013
Antenna Design - 15
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
Satellite Educators Association
California Science Conference 2013
Antenna Design - 16
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)
Satellite Educators Association
California Science Conference 2013
Antenna Design - 17
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)
Satellite Educators Association
California Science Conference 2013
Antenna Design - 18

similar documents