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RF Path Loss in the Vicinity of Steller Sea Lion Haulouts
Alexander Lau
MASc graduate student
Electrical & Computer Engineering
Project Background
• Previous microwave transmission work has been done on buildings and trees but none has been done in a very remote rocky environment
• This research trip to the Queen Charlottes has produced some RF path loss data at haulout sites
• We are using 2.4 and 5.25 GHz due to patch antenna size restrictions and these frequencies are readily available.
Definitions
Link budget: compilation of all the factors that reduce the transmitted power from an antenna of
a transmitter such as the environment in which the signal propagates.
Coverage: the total area where a signal is present.
Overview
• Objective
• Protocol
• Equipment used
• Results
• Future studies
Objective
• To characterize RF path loss at 2.4 GHz and 5.25 GHz at typical haulouts in support of future link budget and coverage studies
• To look for signal interference at 2.4 GHz and 5.25 GHz
Protocol
1. Arrive at the haulout, unpack and set up the test equipment. Place receiver near highest point.
2. Record 2 to 4 signal strength measurements (dBm) at 2.4 and 5.25 GHz, bearing angle, GPS position, inclination angle, and distance between receiver and transmitter at various elevations in ~2m increments.
Constraints
Approximately 30 mins per site, and max. 200 data points.
Portable and battery-powered equipment.
Equipment Used
• XL Microwave 2261 Analyze-R Wideband Receiver - 6 hrs. operating time, 3 hours recharge - light weight (<7 lbs.)- bandwidth is 2 MHz- sensitivity is -100 dBm - 4 selectable frequency bands: 2.400–2.484 GHz,
5.150–5.250 GHz, 5.150–5.250 GHz, 5.725– 5.875 GHz
Equipment Used (cont.)
• XL Microwave 2230 Survey-R Transmitter
- 4–5 hrs. operating time, 3 hours recharge
- 2 tuneable frequency bands: 2.400–2.483 GHz &
5.150–5.999 GHz with 1 MHz resolution
- power output is 10 dBm (0.01 watts)• Geo Explorer XT 128 MB (GPS)• Contour XLRic (laser gun)
Microwave Propagation Fundamentals
• Free-space loss is the attenuation of a signal due to spreading of the electromagnetic wave.
Equation for Free-space loss:
Attenuation(dB) = 92.467 + 20log10(fGHz) + 20log10(Dkm)
Where: fGHz = frequency in GHz
Dkm = distance between antennas in km
Microwave Propagation Fundamentals (cont.)
• Total Path Loss is the sum of the gain of both antennas minus the free space loss and any additional loss such as water vapor, mist, fog, rainfall and Fresnel reflection loss
• Fresnel loss is a multi-path reflection loss due to reflective surfaces such as water, buildings and mountain peaks in the Fresnel zone
• Fading are losses encountered during abnormal propagation conditions such as irregularities and fluctuations in atmospheric temperature, humidity and pressure.
Microwave Propagation Fundamentals (cont.)
• 3 traditional radiation fields exist in free space as a result of the radiated power of an antenna:Near-field – the region closest to the antenna and for which the reactive field dominates over the radiative fields.Fresnel zone – the region between near-field and far-field and for which the radiation fields dominate and angular field distribution depends on distance from the antenna.Far-field – the region where radiation pattern is independent of distance.
Results
Haulout sites :
• McInnes Rocks • Steele Rocks • Warrior Rocks • Langara Rocks
McInnes Rocks
McInnes
Island
Insert Picture
Insert Picture
Signal Strength vs. Distance when Base Station at 1.555 m(Ascending McInnes Rock)
-120
-100
-80
-60
-40
-20
0
0 5 10 15 20 25
Distance (m)
Sign
al S
tren
gth
(dBm
)
2.4 GHz
2.4 GHz Free Space
5.25 GHz
5.25 GHz Free-space
Behind Rock Behind Rock
Steele Rocks
Steele Rocks
Signal Strength vs. Distance when Base Station at 1.555m(Ascending Steele Rock)
-120
-100
-80
-60
-40
-20
0
0 10 20 30 40 50
Distance (m)
Sig
nal
Str
en
gth
(d
Bm
)
2.4 GHz
2.4 GHz Free-space
Behind Rock
Signal Strength vs. Distance when Base Station at 1.555m(Descending Steele Rock)
-120
-100
-80
-60
-40
-20
0
0 5 10 15 20 25 30 35 40 45 50
Distance (m)
Sig
nal S
tren
gth
(dB
m)
5.25 GHz
5.25 GHz Free-space
Behind Rock
Warrior Rocks
Warrior
Rocks
Insert Picture
Insert Picture
Signal Strength vs. Distance when Base Station at 0 m(Ascending Warrior Rocks)
-120
-100
-80
-60
-40
-20
0
0 5 10 15 20
Distance (m)
Sign
al S
tren
gth
(dBm
)
2.4 GHz2.4 GHz Free-space5.25 GHz5.25 GHz Free-space
Behind RockBehind Rock
Signal Strength vs. Distance when Base Station at 1.555 m(Ascending Warrior Rocks)
-120
-100
-80
-60
-40
-20
0
0 5 10 15 20
Distance (m)
Sign
al S
tren
gth
(dBm
)
2.4 GHz2.4 GHz Free-space5.25 GHz5.25 GHz Free-space
Behind RockBehind Rock
Signal Strength vs. Distance when Base Station at 0 m(Descending Warrior Rocks)
-120
-100
-80
-60
-40
-20
0
0 5 10 15 20 25 30
Distance (m)
Sign
al S
tren
gth
(dBm
)
2.4 GHz2.4 GHz Free-space5.25 GHz5.25 GHz Free-space
Line of Sight
Out of Sight
Signal Strength vs. Distance when Base Station at 1.555 m(Descending Warrior Rocks)
-120
-100
-80
-60
-40
-20
0
0 5 10 15 20 25 30
Distance (m)
Sign
al S
tren
gth
(dBm
)
2.4 GHz2.4 GHz Free-space5.25 GHz5.25 GHz Free-space
Line of Sight Out of Sight
Langara Rocks
Langara
Rocks
Insert Picture
Insert Picture
Signal Strength vs. Distance when Base Station at 0 m(Ascending Langara Rocks)
-120
-100
-80
-60
-40
-20
0
0 5 10 15 20 25
Distance (m)
Sign
al S
treng
th (d
Bm)
2.4 GHz
2.4 GHz Free-space
5.25 GHz
5.25 GHz Free-space
Behind RockBehind Rock
Out of View
Peak above Receiver
Peak below Receiver
Signal Strength vs. Distance when Base Station at 1.555 m(Ascending Langara Rocks)
-120
-100
-80
-60
-40
-20
0
0 5 10 15 20 25
Distance (m)
Sign
al S
treng
th (d
Bm)
2.4 GHz Raw Measurement
2.4 GHz Theoretical
5.25 GHz Raw Measurement
5.25 GHz Theoretical
Behind Rock
Behind Rock
Peak above Receiver
Peak below Receiver
Excess Path Loss due to Shadowing when Base Station at 0m
-20
-10
0
10
20
30
40
50
60
-80 -70 -60 -50 -40 -30 -20 -10 0
Depression Angle (degrees)
Exce
ss p
ath
loss
(dBm
)
2.4 GHz
5.25 GHz
Conclusion
Future Studies
• Attend future research trips and devote more time on field measurements
References
• Telecommunication Transmission Handbook, Third Edition by R. L. Freeman (1991)
• Practical Communication Antennas with Wireless Applications by L. Setian (1998)
• Antenna Theory and Design, Second Edition by W. L. Stutzman and G. A. Theile (1997)
• British Columbia topo50 Vol. 2 and 3 by SoftMap (2001)
Acknowledgements
• North Pacific Marine Mammal Consortium
• Dr. Andrew Trites
• Dr. Royann Petrell
• Dr. Dave Michelson
• Dr. William G. Dunford
Questions?