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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).
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)
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]
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.
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)
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.
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.
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.
30 Meter Outdoor Test Range
30 Meter Outdoor Test Range
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.
An R-card Fence
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)
Range with Linear Scanner
Field Probe Data - Horizontal Scan
No fences With fencesVertical Pol
Field Probe Data - Horizontal ScanHorizontal Pol
No fences With fences
Field Probe Data - Vertical Scan
Vertical PolNo fences With fences
Field Probe Data - Vertical ScanHorizontal Pol
No fences With fences
Field Probe Data - Vertical Scan
Horizontal Pol8 GHz 12 GHz
Calibrated Field Probe Data – Vertical Scan
No fences With fencesHorizontal Pol
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
Measured Backscattered Fields – Corner Reflector
Horizontal PolNo fences With fences
Measured Backscattered Fields – Corner ReflectorHorizontal Pol
6 R-card fences
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
The R-card Layout: Layer 1
The R-card Layout: Layer 2
The R-card Layout: Layer 3
The R-card Layout: Layer 4
The R-card Layout: Layer 5
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
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
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
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
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
Measurement Setup
Tx
Rx
260 ft
95 ft 95 ft70 ft
~10 ft
90 in
70 in8' High R-Card Fences
Measurement Setup Behind ESL
Transmit Antenna Receive Antenna
R-card Fences
Receiving Antenna Transmit Antenna
Measurement Setup Behind ESL
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
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).
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.