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Compact and Spherical Range Design, Application and Evaluation
Walter D. Burnside and Inder J. Gupta
The Ohio State UniversityElectroScience Laboratory
1320 Kinnear RoadColumbus, Ohio 43212
(614) 292-5747 and (614) 292-5951
Presented on September 21-22, 2005 for Raytheon (Tucson, AZ).
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Course Outline
Basic Range Design Guidelines (Burnside) Compact Range Reflector Design (Gupta) Absorber Design and Layout (Burnside) Critical Range Evaluation (Gupta)
Second Half Day
First Full Day
R-Card Fences for Outdoor Ranges (Gupta) Summary of Range Design Issues (Burnside)
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R-card Fences to Suppress Ground Bounce Term in Outdoor Facilities
Inder (Jiti) Gupta
ElectroScience LaboratoryDept. of Electrical and Computer Engineering
The Ohio State University1320 Kinnear Road, Columbus, OH 43212
Phone: (614) 292-5951Fax: (614) 292-7297
Email: [email protected]
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Introduction(1)
In outdoor facilities, the ground bounce term can be a limiting factor.
The ground bounce term can destructively interfere with the direct path term reducing the signal level in the quiet zone.
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The transmit antenna height is adjusted so that the direct ray and the ground bounce term add in phase.
– Narrowband solution
Alternatively, metallic fences are used to steer the ground bounce term away from the quiet zone.
Introduction(2)
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R-card Fences
R-card fences have varying resistance where the resistance varies smoothly from a very low value (purely conductor) to very high values.
– Metallic fence can be replaced with a R-card fence.
Transmit signal through the fence can end up in the quiet zone.
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Outdoor Facility with R-card Fences
Multiple R-card fences can be used to eliminate the ground bounce term in the quiet zone.
OSU-ESL has designed and built R-card fences for outdoor facilities.
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Experimental Outdoor Test Range
30 meters longRadar antenna height is 60 cmCenter of target zone is 3 meters above
ground6-18 GHz frequency bandSix R-card fencesFences are tilted 20° towards the feed.
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30 Meter Outdoor Test Range
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30 Meter Outdoor Test Range
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R-card Fences
Each fence is 60 cm tall.
Bottom one third of a fence is pure metal.
Resistance increases smoothly from pure metal to 1150 ohms.
Built using ten layers of flat resistively coated thin films.
Resistive taper on both sides, too.
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Field Probe Data
Radar – HP8510 network analyzer
Radar Antenna – SA 8-12 GHz standard gain horn
Probe Antenna – AEL 2-18 GHz horn
LNA behind the AEL horn to compensate for the cable loss
Horizontal and vertical polarization
A vertical scan (center 3 meters above ground)
A horizontal scan (3meters above ground)
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Range with Linear Scanner
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Field Probe Data - Horizontal Scan
No fences With fencesVertical Pol
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Field Probe Data - Horizontal ScanHorizontal Pol
No fences With fences
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Field Probe Data - Vertical Scan
Vertical PolNo fences With fences
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Field Probe Data - Vertical ScanHorizontal Pol
No fences With fences
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Field Probe Data - Vertical Scan
Horizontal Pol8 GHz 12 GHz
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Calibrated Field Probe Data – Vertical Scan
No fences With fencesHorizontal Pol
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Backscatter Measurements
1-foot corner reflector
Backscattered fields along the boradside direction
Corner reflector at various heights
8.5 GHz to 12.5 GHz frequency band in 2 MHz steps
Two separate antennas for transmit and receive to perform S12 measurements
Time gating (25 point smoothing) to isolate the corner reflector return
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Measured Backscattered Fields – Corner Reflector
Horizontal PolNo fences With fences
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Measured Backscattered Fields – Corner ReflectorHorizontal Pol
6 R-card fences
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Multilayered R-card Fences
The R-card fences discussed until now have strong reflected field term.
In some applications, the reflection term is also undesired.
Multilayered R-card fences have been designed and built for these applications
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The R-card Layout: Layer 1
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The R-card Layout: Layer 2
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The R-card Layout: Layer 3
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The R-card Layout: Layer 4
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The R-card Layout: Layer 5
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Near Field Data for Single Layer R-Card Fence Design
Plot Convention: #L#C##L: number of layers per R-Card Fence#C: number of R-Card Fences#: Separation between two adjacent R-Card Fences
Total Field at Receiver Site Reflected Field at Transmitter Site
Field Probe Pattern at Z=80 metersFrequency = 1575 MHz
Reflected Field Back to the Source0.56 inch Foam
Vertical Probe Position (meters)
0 1 2 3 4 5 6
Sca
tter
ed F
ield
at
Tra
nsm
itter
(dB
)0
5
10
15
20
25
30
35
40
1L1C001L3C081L3C12 1L3C16
Field Probe Pattern at Z=80 metersFrequency = 1575 MHz
Total Field 0.56 inch Foam
Vertical Probe Position (meters)
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0
Tot
al P
robe
Fie
ld a
t R
ecei
ver
(dB
)
0
5
10
15
20
25
30
35
40
Direct1L1C001L3C081L3C121L3C16
3 Fences
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Near Field Data for 3 Layer R-Card Fence Design
Plot Convention: #L#C##L: number of layers per R-Card Fence#C: number of R-Card Fences#: Separation between two adjacent R-Card Fences
Total Field at Receiver Site Reflected Field at Transmitter Site
Field Probe Pattern at Z=80 metersFrequency = 1575 MHz
Total Field 0.56 inch Foam
Vertical Probe Position (meters)
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0
Tot
al P
robe
Fie
ld a
t R
ecei
ver
(dB
)
0
5
10
15
20
25
30
35
40
Direct3L1C003L3C083L3C123L3C16
Field Probe Pattern at Z=80 metersFrequency = 1575 MHz
Reflected Field Back to the Source0.56 inch Foam
Vertical Probe Position (meters)
0 1 2 3 4 5 6
Sca
tter
ed F
ield
at
Tra
nsm
itter
(dB
)0
5
10
15
20
25
30
35
40
3L1C003L3C08 3L3C12 3L3C16
3 Fences
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Near Field Data for 5 Layer R-Card Fence Design
Plot Convention: #L#C##L: number of layers per R-Card Fence#C: number of R-Card Fences#: Separation between two adjacent R-Card Fences
Total Field at Receiver Site Reflected Field at Transmitter Site
Field Probe Pattern at Z=80 metersFrequency = 1575 MHz
Reflected Field Back to the Source0.56 inch Foam
Vertical Probe Position (meters)
0 1 2 3 4 5 6
Sca
tter
ed F
ield
at
Tra
nsm
itter
(dB
)0
5
10
15
20
25
30
35
40
5L1C005L3C085L3C125L3C16
Field Probe Pattern at Z=80 metersFrequency = 1575 MHz
Total Field 0.56 inch Foam
Vertical Probe Position (meters)
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0
Tot
al P
robe
Fie
ld a
t R
ecei
ver
(dB
)
0
5
10
15
20
25
30
35
40
Direct5L1C005L3C085L3C125L3C16
3 Fences
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Near Field Data for 5 Layer R-Card Fence Design
Plot Convention: #L#C##L: number of layers per R-Card Fence#C: number of R-Card Fences#: Separation between two adjacent R-Card Fences
Total Field at Receiver Site Reflected Field at Transmitter Site
3 Fences
Field Probe Pattern at Z=80 metersFrequency = 1575 MHz
Reflected Field Back to the SourceOne inch Foam
Vertical Probe Position (meters)
0 1 2 3 4 5 6
Sca
tter
ed F
ield
at
Tra
nsm
itter
(dB
)0
5
10
15
20
25
30
35
40
5L1C005L3C08 5L3C12 5L3C16
Field Probe Pattern at Z=80 metersFrequency = 1575 MHz
Total Field One inch Foam
Vertical Probe Position (meters)
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0
Tot
al P
robe
Fie
ld a
t R
ecei
ver
(dB
)
0
5
10
15
20
25
30
35
40
Direct5L1C005L3C085L3C125L3C16
1.0” Foam
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Near Field Data for 5 Layer R-Card Fence Design
Plot Convention: #L#C##L: number of layers per R-Card Fence#C: number of R-Card Fences#: Separation between two adjacent R-Card Fences
Total Field at Receiver Site Reflected Field at Transmitter Site
2 Fences
Field Probe Pattern at Z=80 metersFrequency = 1575 MHz
Reflected Field Back to the SourceOne inch Foam
Vertical Probe Position (meters)
0 1 2 3 4 5 6S
catt
ered
Fie
ld a
t T
rans
mitt
er (
dB)
0
5
10
15
20
25
30
35
40
5L1C005L2C14 5L2C22 5L2C30
Field Probe Pattern at Z=80 metersFrequency = 1575 MHz
Total Field One inch Foam
Vertical Probe Position (meters)
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0
Tot
al P
robe
Fie
ld a
t R
ecei
ver
(dB
)
0
5
10
15
20
25
30
35
40
Direct5L1C005L2C145L2C225L2C30
1.0” Foam
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Measurement Setup
Tx
Rx
260 ft
95 ft 95 ft70 ft
~10 ft
90 in
70 in8' High R-Card Fences
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Measurement Setup Behind ESL
Transmit Antenna Receive Antenna
R-card Fences
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Receiving Antenna Transmit Antenna
Measurement Setup Behind ESL
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Ohio University R-Card Fence Measured Probe DataHorizontal Polarization, Tx Antenna Height = 10'
Frequency = 1576 MHz
Receiving Antenna Height (inches)
90 100 110 120 130 140 150 160
Pro
be F
ield
(dB
)
-120
-115
-110
-105
-100
-95
-90
With FenceWithout Fence
Ohio University R-Card Fence Measured Probe DataVertical Polarization, Tx Antenna Height = 10'
Frequency = 1576 MHz
Receiving Antenna Height (inches)
90 100 110 120 130 140 150 160
Pro
be F
ield
(dB
)
-120
-115
-110
-105
-100
-95
-90
With FenceWithout Fence
Probe Field at 1575 MHz
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Summary
R-card fences can be used for performance enhancement of outdoor facilities.
Multi-layered R-card fences can be designed to act like absorber (low-level transmission and reflection).
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References
Y. Kim and E.K. Walton, “Ground bounce reduction using a tapered resistive sheet fence,” AMTA2000, pp. 222-227, Philadelphia, PA, October 2000.
I.J. Gupta and W.D. Burnside, ”Performance of an experimental outdoor RCS range with R-card fences,” AMTA2001, pp.400-405, Denver, CO, October 2001.
T.-H. Lee and W.D. Burnside, “Applications of multilayer resistive strips (R-card) in EM measurements,” AMTA2003, pp 420-425, Irvine, CA, October 2003.