Influence of Antenna Pattern Distortions

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Influence of Antenna Pattern Distortions on
Surface Current Data collected by a CODAR
HF-Radar System
Josh T. Kohut Scott M. Glenn Donald E.
Barrick
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(No Transcript)
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Radial Velocity Map
Brant Beach Site
Brigantine Site
Moored ADCP
25 km
A
25 cm/s
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Radial Velocity Map
Brant Beach Site
Brigantine Site
Location
Moored ADCP

• Range
• Bearing

25 km
A
25 cm/s
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AntennaPatterns
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Role of Antenna Patterns in Signal Direction
Determination
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Role of Antenna Patterns in Signal Direction
Determination
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Measured vs. Ideal Antenna Patterns
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Calibration Runs
Ground Plane
Run Number
Environment
Antenna
Date
1 2.4 m Brigantine Brigantine
10/99
2 1.2 m Brigantine Brigantine
10/99
3 2.4 m Brant Beach Brant Beach
10/99
4 1.2 m Brant Beach Brant Beach
10/99
5 1.2 m Brant Beach Brant Beach
09/00
6 1.2 m Brant Beach Brigantine
09/00
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Calibration Runs
Ground Plane
Run Number
Environment
Antenna
Date
1 2.4 m Brigantine Brigantine
10/99
2 1.2 m Brigantine Brigantine
10/99
3 2.4 m Brant Beach Brant Beach
10/99
4 1.2 m Brant Beach Brant Beach
10/99
5 1.2 m Brant Beach Brant Beach
09/00
6 1.2 m Brant Beach Brigantine
09/00
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Measured Brant Beach Antenna Patterns
2.4 m Ground Plane
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Brant Beach Antenna Distortions
2.4 m Ground Plane
1.2 m Ground Plane
0.5 0.4 0.3 0.2 0.1 0.0 -0.1 -0.2 -0.3 -0.4 -0.5
40 60 80 100 120 140 160
180 200 220
40 60 80 100 120 140 160
180 200 220
Angle (Degrees From True North)
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Calibration Runs
Ground Plane
Run Number
Environment
Antenna
Date
1 2.4 m Brigantine Brigantine
10/99
2 1.2 m Brigantine Brigantine
10/99
3 2.4 m Brant Beach Brant Beach
10/99
4 1.2 m Brant Beach Brant Beach
10/99
5 1.2 m Brant Beach Brant Beach
09/00
6 1.2 m Brant Beach Brigantine
09/00
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Antenna Distortions
Brant Beach, NJ
0.5 0.4 0.3 0.2 0.1 0.0 -0.1 -0.2 -0.3 -0.4 -0.5
40 60 80 100 120 140 160
180 200 220
Angle (Degrees From True North)
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Calibration Runs
Ground Plane
Run Number
Environment
Antenna
Date
1 2.4 m Brigantine Brigantine
10/99
2 1.2 m Brigantine Brigantine
10/99
3 2.4 m Brant Beach Brant Beach
10/99
4 1.2 m Brant Beach Brant Beach
10/99
5 1.2 m Brant Beach Brant Beach
09/00
6 1.2 m Brant Beach Brigantine
09/00
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Brigantine Antenna Distortions
Brigantine, NJ
0.5 0.4 0.3 0.2 0.1 0.0 -0.1 -0.2 -0.3 -0.4 -0.5
40 60 80 100 120 140 160
180 200 220
Angle (Degrees From True North)
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Brant Beach Pattern Distortions
Antenna A
Antenna B
0.5 0.4 0.3 0.2 0.1 0.0 -0.1 -0.2 -0.3 -0.4 -0.5
40 60 80 100 120 140 160
180 200 220
40 60 80 100 120 140 160
180 200 220
Angle (Degrees From True North)
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ADCP Comparisons
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Radial Velocity Map
Brant Beach Site
Brigantine Site
Moored ADCP
25 km
A
25 cm/s
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Ideal or Measured Pattern
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ADCP and CODAR Radial Velocity Comparisons
RMS (cm/s)
R2 ()
Ground Plane
Remote Site
2.4 m Brant Beach 12.2
60
2.4 m Brant Beach 10.3
79
1.2 m Brant Beach 10.1
79
1.2 m Brant Beach 9.8
77
Ideal Patterns
Measured Patterns
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Brant Beach Antenna Patterns
2.4 m Ground Plane
1.2 m Ground Plane
0.5 0.4 0.3 0.2 0.1 0.0 -0.1 -0.2 -0.3 -0.4 -0.5
A D C P
A D C P
40 60 80 100 120 140 160
180 200 220
40 60 80 100 120 140 160
180 200 220
Angle (Degrees From True North)
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ADCP and CODAR Radial Velocity Comparisons
RMS (cm/s)
R2 ()
Ground Plane
Remote Site
2.4 m Brigantine 8.2
81
2.4 m Brigantine 7.2
90
1.2 m Brigantine 8.7
86
1.2 m Brigantine 8.9
88
Ideal Patterns
Measured Patterns
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Brigantine Antenna Patterns
2.4 m Ground Plane
1.2 m Ground Plane
0.5 0.4 0.3 0.2 0.1 0.0 -0.1 -0.2 -0.3 -0.4 -0.5
A D C P
A D C P
40 60 80 100 120 140 160
180 200 220
40 60 80 100 120 140 160
180 200 220
Angle (Degrees From True North)
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Measuredvs.Ideal
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Radial Velocity Map
Location

• Range
• Bearing

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CODAR and ADCP Radial Velocity Comparisons (2.4 m)
50 45 40 35 30 25 20 15 10 5 0
Ideal Patterns Measured Patterns
A D C P
RMS Difference (cm/s)
20 40 60 80 100 120 140
160 180 200 220
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gt30 25 20 15 10 5 0
Spatial Difference Between Measured and Ideal
Patterns (2.4 m)
200 150 100 50 0 -50 -100 -150 -200
Relative Angle (Degrees)
RMS Difference (cm/s)
45 65 85 105 125 145
165 185 205
Reference Angle (Degrees from True North)
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gt30 25 20 15 10 5 0
Spatial Difference Between Measured and Ideal
Patterns (1.2 m)
200 150 100 50 0 -50 -100 -150 -200
Relative Angle (Degrees)
RMS Difference (cm/s)
45 65 85 105 125 145
165 185 205
Reference Angle (Degrees from True North)
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Conclusions

• Hardware setup and local environment play a
  significant role in pattern distortions.
• System accuracy improves when the measured
  pattern is used, if the measured pattern is not
  ideal.
• If the measured pattern is not significantly
  distorted, results using either the measured or
  ideal pattern show a strong correlation to a
  moored ADCP.
• Using the measured pattern improves system
  accuracy by more consistently placing a velocity
  vector in the correct angular bin.

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Acknowledgements

• Scott Glenn
• John Fracassi
• Sage Lichtenwalner
• Don Barrick
• Pete Lilliboe
• Laura Pederson

• Belinda Lipa
• Liz Creed
• Mike Crowley
• Kristie Andreson
• Capt. Ron
• Capt. Joe