### 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

reaches Earth
surface
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Antenna Design - 3


Surface features
reflect solar
remote sensors
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Antenna Design - 4



Satellite sends
remote sensors to
Earth station
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Antenna Design - 5
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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Antenna Design - 6
Electromagnetic Spectrum
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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
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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
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Antenna Design - 9
Build Wave Model: 1/10 Scale
wavelength: λ = 2.18 m
1/
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10
scale model wave:
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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
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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
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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
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Antenna Design - 13
Brent Stirton, http://ngm.nationalgeographic.com
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Antenna Design - 14
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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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
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Antenna Design - 16
CA Science Standards
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)
meaningful questions and conducting careful
investigations (a, d, g)
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Antenna Design - 17
Contact Information
 Pete Arvedson - [email protected]/* <![CDATA[ */!function(t,e,r,n,c,a,p){try{t=document.currentScript||function(){for(t=document.getElementsByTagName('script'),e=t.length;e--;)if(t[e].getAttribute('data-cfhash'))return t[e]}();if(t&&(c=t.previousSibling)){p=t.parentNode;if(a=c.getAttribute('data-cfemail')){for(e='',r='0x'+a.substr(0,2)|0,n=2;a.length-n;n+=2)e+='%'+('0'+('0x'+a.substr(n,2)^r).toString(16)).slice(-2);p.replaceChild(document.createTextNode(decodeURIComponent(e)),c)}p.removeChild(t)}}catch(u){}}()/* ]]> */
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