Out of this WorldAntenna Measurements
SAREX Behind the Scenes
2014 July 9Kai Siwiak, KE4PT
prepared for the
2014 July 9 KE4PT slide 2
Part – I: Antenna Ranges
pager
30 meters signal source
transmit antenna
Typical OATS antenna range: Typical indoor anechoic range:
… In a river bed in China … in Boca Raton, Florida
2014 July 9 KE4PT slide 3
Part – I: Antenna Ranges
pager
30 meters signal source
transmit antenna
Typical OATS antenna range: Typical indoor anechoic range:
… In a river bed in China … in Boca Raton, Florida
… the way Hams did it with NASA’s help
2014 July 9 KE4PT slide 4
Background: SAREX (now ARISS)
• In the Public Eye– Random contacts with Hams World Wide– Contacts and Educational activities with schools and
youth groups– Visibility for NASA
• Behind the Scenes– SAREX support for missions and new capabilities– Crew phone patches with Family– Special propagation experiments– Ham ATV experiments
2014 July 9 KE4PT slide 5
STS-80STS-71STS-65STS-58
STS-931999STS-94STS-831997
STS-81STS-79STS-78STS-761996STS-74STS-70STS-67STS-631995
STS-64STS-60STS-591994STS-57STS-56STS-551993STS-50STS-47STS-451992
STS-371991STS-351990
STS-61ASTS-51F1985STS-91983
MissionYear
More details : http://ct1eat.no.sapo.pt/sarex/sarexm_e.html
ColumbiaChallengerAtlantis DiscoveryEndeavor
2014 July 9 KE4PT slide 6
SAREX Started After STS-9
Chuck, W4ROA
Kai, KE4PT Owen,
W5LFL Harold, KT4XK
2014 July 9 KE4PT slide 7
SAREX Kick–off MeetingKai, KE4PT
Owen, W5LFL
Tom, K4GFG
Harold, KT4XK
George M,Motorola PR
2014 July 9 KE4PT slide 8
top, left to right … Lou, W5DID, [SAREX P.I.]Kai, KE4PT, [Volunteer]Owen, W5LFL, [Astronaut]
Kai on OV-102 Columbiawith STS-9 antenna
2014 July 9 KE4PT slide 9
…The cast included hundreds!
2014 July 9 KE4PT slide 10
STS-71STS-65STS-58
STS-931999STS-94STS-831997
STS-79STS-78STS-761996STS-74STS-70STS-67STS-631995
STS-64STS-60STS-591994STS-57STS-56STS-551993STS-50STS-47STS-451992
STS-371991STS-351990
STS-51F1985STS-91983
MissionYear
More details : http://ct1eat.no.sapo.pt/sarex/sarexm_e.html
COLUMBIAWindow Antenna Gain Test
2014 July 9 KE4PT slide 11
The Experiment
• NASA asked Hams to measure gain of SAREX window antenna
• Motorola-ARC and IBM-ARC responded with detailed measurements
• Many Hams sent signal reports
2014 July 9 KE4PT slide 12Source: QST Oct 1993 p53-55
Mor
e C
ast
Mem
bers
2014 July 9 KE4PT slide 13
Space Lab Module on Columbia
Space Lab D2 antenna
[old STS-9 antenna]
SAREX antenna
source: http://en.wikipedia.org/wiki/Spacelab
2014 July 9 KE4PT slide 14
Space Shuttle Windows
source: framework.latimes.com/2012/09/12/space-shuttle-endeavour/
2014 July 9 KE4PT slide 15
We Used Two Consecutive Orbits Visible From Plantation, FL
Source: QuikTrack tracking program, AMSAT, Silver Spring, MD
2014 July 9 KE4PT slide 16
SpectrumAnalyzer
VCR Polarization
switch
Trackingcomputer
Az / Elcontrol
Vertically polarized Yagi
Horizontally polarized Yagi
Source: K. Siwiak & Y. Bahreini, Radiowave Propagation and Antennas for Personal Communications, Third Edition, Norwood, MA: Artech House, 2007
Configuration for TestVertically polarized Yagi
Horizontally polarized Yagi
Vertically polarized Yagi
Horizontally polarized Yagi
Vertically polarized Yagi
Horizontally polarized Yagi
Vertically polarized Yagi
Horizontally polarized Yagi
2014 July 9 KE4PT slide 17
What We Found
• We measured signal strength in two polarizations with:– Astronaut using the Window antenna (rev 61) – Astronaut using D2 Spacelab antenna (rev 62)
• Calculated Antenna Gain• Calculated Faraday Rotation (the rotation of
polarization as a signal passes through the charged ionosphere under influence of Earth’s magnetic field)
2014 July 9 KE4PT slide 18
200 600 1000 1400 1800 2200-35
-30
-25
-20
-15
-10
-5
05
10
Antenna Range, km
Ant
enna
Gai
n, d
Bi
Window antenna rev 61SpaceLab antenna rev 62
Using the 2nd Longest Antenna Range in the Solar System to Measure Gain
10~11 dB Start of pass
End of passClosest approach
2014 July 9 KE4PT slide 19
Paths through the Ionosphere
• Electron density known after the flight and tests (so, we can calculate Faraday Rotation)
• Different path lengths result in different amount of Faraday rotation
2014 July 9 KE4PT slide 20
Ionosphere during rev 61/62 gives us electron density
31022 /10)2(24.1 melectronsfoFNmF
2014 July 9 KE4PT slide 21
0 100 200 300 400 5000
30
60
90
Time, sec
DegCalculated: about a ¼ turnMeasured: about a ¼ turn
Source: K. Siwiak & Y. Bahreini, Radiowave Propagation and Antennas for Personal Communications, Third Edition, Norwood, MA: Artech House, 2007
0 120 240 360 480 6000
30
60
90
Time, sec
Deg
Bottom Line:
Orbit 61
Orbit 62
CalculatedMeasured
222
)(
20
203
fmc
dzzNBeTurns
e
zmFe
2014 July 9 KE4PT slide 22
Bottom Line…
• Antenna Range DX was 180 – 1800 miles• The Window VHF antenna was –10 dBi• Faraday rotation is significant!
• Consequence: Today’s ARISS contacts use gain antennas and circular polarization
2014 July 9 KE4PT slide 23
The Longest Antenna Range?
• SAREX STS-55 was my 2nd Longest Antenna Range Measurement (300 km to 2,200 km)
• My “best DX” antenna gain measurement was on a 720,000 km (447,000 mile) range, and at HF[That’s Part – II: for another day!]
2014 July 9 KE4PT slide 24
Thanks for your attention!
Kai, KE4PT
Download: www.qsl.net/k4fk/presentations.htm