1. Compact and Spherical Range Design, Application and Evaluation
Walter D. Burnside and Inder J. Gupta
The Ohio State University
ElectroScience Laboratory
1320 Kinnear Road
Columbus, Ohio 43212
(614) and (614)
Presented on September 21-22, 2005 for Raytheon (Tucson, AZ).

2. Course Outline First Full Day Second Half Day
Basic Range Design Guidelines (Burnside)
Compact Range Reflector Design (Gupta)
Absorber Design and Layout (Burnside)
Critical Range Evaluation (Gupta)
Second Half Day
R-Card Fences for Outdoor Ranges (Gupta)
Summary of Range Design Issues (Burnside)

3. R-card Fences to Suppress Ground Bounce Term in Outdoor Facilities
Inder (Jiti) Gupta
ElectroScience Laboratory
Dept. of Electrical and Computer Engineering
The Ohio State University
1320 Kinnear Road, Columbus, OH 43212
Phone: (614)
Fax: (614)

4. 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.

5. Introduction(2)
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.

6. 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.

7. 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.

8. Experimental Outdoor Test Range
30 meters long
Radar antenna height is 60 cm
Center of target zone is 3 meters above ground
6-18 GHz frequency band
Six R-card fences
Fences are tilted 20° towards the feed.

9. 30 Meter Outdoor Test Range

10. 30 Meter Outdoor Test Range

11. 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.

12. An R-card Fence

13. 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)

14. Range with Linear Scanner

15. Field Probe Data - Horizontal Scan
Vertical Pol
No fences
With fences

16. Field Probe Data - Horizontal Scan
Horizontal Pol
No fences
With fences

17. Field Probe Data - Vertical Scan
Vertical Pol
No fences
With fences

18. Field Probe Data - Vertical Scan
Horizontal Pol
No fences
With fences

19. Field Probe Data - Vertical Scan
Horizontal Pol
8 GHz
12 GHz

20. Calibrated Field Probe Data – Vertical Scan
Horizontal Pol
No fences
With fences

21. 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

22. Measured Backscattered Fields – Corner Reflector
Horizontal Pol
No fences
With fences

23. Measured Backscattered Fields – Corner Reflector
Horizontal Pol
6 R-card fences

24. 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

25. The R-card Layout: Layer 1

26. The R-card Layout: Layer 2

27. The R-card Layout: Layer 3

28. The R-card Layout: Layer 4

29. The R-card Layout: Layer 5

30. Near Field Data for Single Layer R-Card Fence Design
Total Field at Receiver Site
Reflected Field at Transmitter Site
3 Fences
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

31. Near Field Data for 3 Layer R-Card Fence Design
Total Field at Receiver Site
Reflected Field at Transmitter Site
3 Fences
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

32. Near Field Data for 5 Layer R-Card Fence Design
Total Field at Receiver Site
Reflected Field at Transmitter Site
3 Fences
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

33. Near Field Data for 5 Layer R-Card Fence Design
Total Field at Receiver Site
Reflected Field at Transmitter Site
1.0” Foam
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
3 Fences

34. Near Field Data for 5 Layer R-Card Fence Design
Total Field at Receiver Site
Reflected Field at Transmitter Site
1.0” Foam
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
2 Fences

35. Measurement Setup

36. Measurement Setup Behind ESL
Transmit Antenna
Receive Antenna
R-card Fences

37. Measurement Setup Behind ESL
Receiving Antenna
Transmit Antenna

38. Probe Field at 1575 MHz

39. 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).

40. References
Y. Kim and E.K. Walton, “Ground bounce reduction using a tapered resistive sheet fence,” AMTA2000, pp , Philadelphia, PA, October 2000.
I.J. Gupta and W.D. Burnside, ”Performance of an experimental outdoor RCS range with R-card fences,” AMTA2001, pp , Denver, CO, October 2001.
T.-H. Lee and W.D. Burnside, “Applications of multilayer resistive strips (R-card) in EM measurements,” AMTA2003, pp , Irvine, CA, October 2003.