Electromagnetic Radiation & Satellites Antenna Design Pete Arvedson California Science Conference October 26, 2013 Hosted by Satellite Educators Association

Electromagnetic Radiation & Satellites

Antenna Design

Pete Arvedson

California Science Conference

October 26, 2013

Hosted by Satellite Educators AssociationLesson plan development supported by a grant from NOAA-CREST West

Session Objectives

Relate wavelength and frequencyConstruct 1/10th scale model waveCalculate antenna lengthApply to 5-element Yagi antenna designBuild 1/10th scale antenna

Satellite Educators Association California Science Conference 2013 Antenna Design - 2

Solar radiation reaches Earth surface


Surface features reflect solar radiation to remote sensors


Satellite sends radio signal from remote sensors to Earth station


Wave Properties

crest

trough

wavelength, λ (meters)

amplitude

How many waves pass a point each second

= frequency, ν (1/sec or Hertz)Satellite Educators Association California Science Conference 2013 Antenna Design - 6

Electromagnetic Spectrum


Wave Properties

c = speed of light = 299,792,458 m/s

-in vacuum ~ 300 x 106 m/s

-in metal = 280.225 x 106 m/s

cλ ν

c = λν

λ = c / ν

ν = c / λ


POES WEFAX frequency = 137.50 MHz

λ = c / ν

λ =

Wavelength from Frequency

m 2.18 Hz 10 x 137.5

m/s 10 x 3006

6


Build Wave Model: 1/10 Scale

1/10 scale model wave: λ = 21.8 cm

wavelength: λ = 2.18 m


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


Antenna Size - Actual

Hz 10 x 137.5

m/s 10 x 280.225

frequency

metalin velocity λ

6

6

2.182 m

½ wavelength = 1.019 m

1/10 scale model antenna length = 10.19 cm

Hz 10 x 137.5

m/s 10 x 300

frequency

in vacuumvelocity λ

6

6

2.038 m


Yagi Antenna

1926 Hidetsugu Yagi & Sintaro UdaTohoku Imperial University, Japan

Driven element; parasitic directors & reflectorHighly directional & wavelength selective


Brent Stirton, http://ngm.nationalgeographic.comSatellite Educators Association California Science Conference 2013 Antenna Design - 14

Design Your Antenna

3.0 cm8.74 cm

92.0 cm9.20 cm

96.8 cm9.68 cm

10.19 cm

112.1 cm11.21 cm

87.4 cm

4.1 cm

18.3 cm


Extension

Build scale models other antenna typesCalculate antenna length for 1693 MHzBuild several real antennas & determine

which is best for satellite receptionCompare/Contrast crossed Yagi with QHABuild chicken wire parabolic reflector


CA Science Standards

Grades 9-12: Physics4. 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 & E1. Scientific progress is made by asking

meaningful questions and conducting careful investigations (a, d, g)


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)


Documents

Electromagnetic Radiation & Satellites Antenna Design Pete Arvedson California Science Conference October 26, 2013 Hosted by Satellite Educators Association