1. DESIGN OF MUTUALLY TRANSPARENT ANTENNA ARRAYS
Syntonics Weekly Report
4/19/2017
DESIGN OF MUTUALLY TRANSPARENT ANTENNA ARRAYS
JOHDPUR  FEB ,2008
AND
BANGALORE  MAR. 3-4, 2008
Dr. Eric K. Walton
The Ohio State University
ElectroScience Lab.
ERIC K. WALTON

2. BASIC CONCEPT OF THE FSS ARRAY ANTENNA CLUSTER
BEAM 1
BEAM 2
BEAM 3
ARRAY 2
ARRAY 1
RADOME
ARRAY 3
MECHANICALLY STEERED BEAMS
MUTUALLY TRANSPARENT ANTENNA ARRAYS MOUNTED INSIDE A RADOME

3. EACH OUTER ARRAY ANTENNA IS TRANSPARENT TO THE INNER ARRAYS
BASIC ARRAY CONCEPT
EACH TRANSPARENT ANTENNA PANEL:
STYROFOAM
DIELECTRIC
RADIATING ELEMENTS
PRINTED ON MYLAR
FSS TRANSMISSION LINES PRINTED ON DUROID
FSS GROUND PLANE
PRINTED ON MYLAR
EACH OUTER ARRAY ANTENNA IS TRANSPARENT TO THE INNER ARRAYS

4. MUTUALLY TRANSPARENT FSS ARRAY ANTENNAS
TRANSMISSION LINE
DESIGN AND TESTING

5. Center part of layout; view from top
This layout is only so that the basic repeating pattern can be understood.
Red = transmission lines
Yellow = slots in foam
Orange = holes in foam/Mylar
Green = FSS pattern on Mylar
(ant. Elements not shown)

6. RF Transparent Array Antenna for Dense Array Cluster
Branch lines
Main trunk line
Proportional power directional couplers
Rotatable feed stubs
The transmission line array was perhaps the most complex part of the entire system. (See presentation by Eugene Lee)

7. TRANSMISSION LINE LOCATION
Radiating CP dipoles
FSS Ground Plane
Transmission Line
GAP “D”

8. THE TRANSMISSION LINE FEED SYSTEM

9. TRANSMISSION LINE FEED SYSTEM Single branch tap

10. S band transmission line distribution at 2230 MHz

11. MUTUALLY TRANSPARENT FSS ARRAY ANTENNAS
RADIATING ELEMENT
DESIGN AND TESTING

12. Resonant Frequency = 1697MHz Input Impedance = 61.914 + j 0.080773 Ω
A DUAL RHOMBIC LOOP ANTENNA FOR CIRCULAR POLARISATION
H. Morishita , T. Iizuka, K. Hirasawa and T.Nagao
Length of side = 0.354λ = mm
Size of break = 0.016λ = 2.82 mm
Size of connector = 8 mm
Resonant Frequency = 1697MHz
Input Impedance = j Ω
Max gain = dBi
Antennas and Propagation, 4-7 April 1995
Conference Publication No. 407,O IEE 1995.

13. Comparison of Element Designs
Cut Corners
Concave Corners
Element Radius = 0.45λ (0.079m)
Single Loop Circumference = 1.33λ (0.236m)
MHz = – j Ω
Element Radius = 0.45λ (0.079m)
Single Loop Circumference = 1.40λ (0.248m)
MHz = – j 2.387
Square Corners
(original element)
Element Radius = 0.52λ (0.092m)
Single Loop Circumference = 1.40λ (0.248m)
MHz = – j Ω

14. Figure 2: Sample FSS Configuration
S-band Arrays
Single element side length and break position was optimized for peak gain at resonance (see appended slides)
14x14 array simulated over ‘+x+x+’ FSS ground planes of different sizes (results on following three slides) s
Figure 1: Sample S-band Element (side length, s = 0.34λ2230MHz; break position = 2/3)
Figure 2: Sample FSS Configuration

15. RF Transparent Array Antenna for Dense Array Cluster
Flat loop antenna

16. Abused (cold) grad students:
RF Transparent Array Antenna for Dense Array Cluster
TESTING THE FLAT LOOP ANTENNA
Abused (cold) grad students:
Eugene Lee (PHD)
And Ryan Pavlovicz (Senior – soon to be grad student)

17. MUTUALLY TRANSPARENT FSS ARRAY ANTENNAS
FSS GROUND PLANE
DESIGN AND TESTING

18. FSS GROUND PLANE PRINTED ON MYLAR
RADIATING ELEMENTS AND FSS GROUND PLANE ARE MADE OF
COPPER OR SILVER PRINTED ON MYLAR
DIELECTRIC SUBSTRATE IS SIMPLY A PANEL OF STYROFOAM
(THE MYLAR LAYERS GIVE IT STRENGTH AND RIGIDITY)
THE TRANSMISSION LINE STRUCTURE IS
TWIN LINES PRINTED ON STABLE DIELECTRIC

19. FSS

20. Array with FSS

21. MUTUALLY TRANSPARENT FSS ARRAY ANTENNAS
FULL SYSTEM
DESIGN AND TESTING

22. TRANSMISSION LINE SYSTEM
FULL SYSTEM MODELING
RADIATING ELEMENTS;
FSS LAYER;
TRANSMISSION LINE SYSTEM
EXAMPLE; WIRE GRID MODEL OF L-BAND ARRAY BLOCKING S-BAND ARRAY

23. S-band Octagonal Array
MODELING RESULTS
S-band Octagonal Array
156 Elements
Input impedance ~ j17.6Ω
Boresite gain = dBiC
162 x 152 FSS ground plane

24. S-Band Boresight gain vs. frequency for individual quadrants

25. CR BLOCKAGE Experimental Setup
Walton
(not to scale)
ANTENNA ARRAY PANELS
(SET UP FOR TRANSMISSIVITY TESTING)
Range center line
Eugene’s
Slide
~(12’ x 6’ x 5”)
84”
ROTATE
Support Legs
SLIDE
Foam Support columns

26. COMPACT RANGE BLOCKAGE TESTING
ARRAYS
HANDSOME
GRAD STUDENT
FOAM SUPPORTS

27. ANALYSIS OF EXPERIMENTAL TESTING
S band array at boresight vs. L band array blockage
Percent blockage results
GAIN (DBIC) VS. FREQ. (MHZ)

28. S band array patterns @ 2170 MHz for different blockage %
GAIN (DBIC)
S band blocked by L-band array
NONE; 0%; 25%; 50%; 75%; 100%
AZIMUTH (DEG)

29. S band array patterns @ 2170 MHz for different occlusion % [zoom]
GAIN (DBIC)
S band blocked by L-band array
NONE; 0%; 25%; 50%; 75%; 100%
AZIMUTH (DEG)

30. S band array patterns @ 2170 MHz for different occlusion % [zoom 2x]
No blockage
50% blockage
GAIN (DBIC)
100 % blockage
S band blocked by L-band array
NONE; 0%; 25%; 50%; 75%; 100%
S band blocked by L-band array
NO; EDGE; 25%; 50%; 75%; 100%
AZIMUTH (DEG)

31. Full Array gain max Freq Boresight Gain HPBW (deg) HPBW gain (50% eff)
Theoretical
2230 MHz
32.06 dBiC
4.2
30.14
Outdoor
2020 MHz
22.05 dBiL / dBiL 4
30.56
Anechoic Chamber
2170 MHz
22.12 dBiC 5
28.62
Synthesized from LR quadrant
2245 MHz
23.89 dBiC
4.1
30.35

32. PROTOTYPE READY FOR TESTING
PROTOTYPE INTEGRATION:
SUPPORT MECHANISM
POSITIONING MECHANISM
EM TRANSPARENT ARMS
PATENTED
APRIL 13, 2007
BEAMS ARE STEERED USING ONLY LOW-POWER SERVOMECHANISMS

33. PROTOTYPE TESTING IN OSU/ESL COMPACT RANGE
1. Handsome Grad Student
2. Old professor
3. Smart engineer

34. Calibrated S band Boresight Gain Measurements in outdoor area
~17.3 dBiL

35. Calibrated S band Boresight Gain Measurements in OSU compact range

36. Compact Range - Boresight @ 2170 MHz (270/0 cut)UR UL LR LL
Array
Array-cable, div
H (dBiL)
14.50 / 13.78
10.91 / 11.34
14.49 / 14.11
9.32 / 7.08
15.97 / 14.12
19.35 / 17.50
V (dBiL)
13.92 / 14.44
10.46 / 11.63
14.96 / 13.93
9.68 / 8.67
15.64 / 13.84
19.02 / 17.21
RHCP (dBiC)
17.09 / 17.10
13.69 / 14.44
17.67 / 17.02
12.51 / 10.92
18.75 / 17.09
22.12 / 20.36
HPBW (deg)
8.5 / 13
12.25 / 8
8.75 / 8
8 / 9
5 / 5 5

37. Discuss only if questions
MHz (270 cut) UR UL LR LL
Array
Array-cable, div
Syn. Array
H (dBiL)
12.18
9.78
13.87
6.50
13.89
17.26
19.89
V (dBiL)
12.78
9.72
12.70
6.36
13.86
17.23
18.72
RHCP (dBiC)
15.24
12.76
16.26
9.44
16.81
20.18
22.28
HPBW (deg) 8
9.5
7.5 5 4
Discuss only if questions

38. As expected Full Array gain study Too low Freq Boresight Gain
HPBW (deg)
HPBW gain (50% eff)
Theoretical
2230 MHz
32.06 dBiC
4.2
30.14
Outdoor
2020 MHz
22.05 dBiL / dBiL 4
30.56
Anechoic Chamber
2170 MHz
22.12 dBiC 5
28.62
Synthesized from LR quadrant
2245 MHz
23.89 dBiC
4.1
30.35
Too low
In tracking down where the 10 dB went, we discovered that the silver printed on Mylar had slowly oxidized. Both the FSS ground plane elements and the radiating elements were now resistive. (20 to 50 ohms end-to-end!)

39. SUMMARY OF RESEARCH SO FAR
WE BUILT AND TESTED A 3-ANTENNA SYSTEM
PARTNERS: (SBIR PHASE 1 AND 2) (PHASE 3 HOPEFUL)
SPAWAR SAN DIEGO
THE OSU ELECTROSCIENCE LAB. (ERIC WALTON)
SYNTONICS LLC (BRUCE MONTGOMERY)
PROBLEMS OVERCOME: (DESIGN, CONSTRUCTION , TESTING)
EM TRANSPARENT RADIATING ELEMENTS
EM TRANSPARENT FSS GROUND PLANE
EM TRANSPARENT DIELECTRIC SUPPORT PANEL
EM TRANSPARENT TRANSMISSION LINE FEED SYSTEM
EM TRANSPARENT SUPPORT ARMS
EM TRANSPARENT PANEL SUPPORT STEERING MECHANISM/CONTROL
TEST AND EVALUATION PROCESS
AND IT WORKED VERY WELL (GAIN; SIDELOBES; POLARIZATION; MUTUAL INDEPENDENCE)

40. FUTURE RESEARCH EXPECTED:
(6.1 research program)
GENERALIZE THE DESIGN OF FSS TRANSMISSION LINE FEED NETWORKS (this is a PHD problem & is now in progress (Eugene Lee) )
GENERALIZE THE DESIGN OF THE MULTIPLE ARRAY SYSTEM (other groups will need to do their own specialized designs)
(6.2 research program)
OPTIMIZE THE DESIGN OF THE SYSTEM COMPONENTS (ELEMENTS, FSS, TRANSMISSION LINES) (better & lower cost components, interconnections and structural supports to be developed)
OPTIMIZE THE PRINTING OF COPPER OR SILVER LINES ON MYLAR (practical chemistry problems to be overcome)
OPTIMIZE THE INTEGRATION OF THE “STACK” (better materials, low dielectric adhesives, interconnections between printed conductive lines and the transmission line network, possible spherical segment shapes for arrays)
(6.3 research program)
BUILD AND TEST A FULLY OPERATIONAL PROTOTYPE SYSTEM (demonstrate tracking of multiple satellites; provide operational data)
DEVELOP LOW COST AND EFFECTIVE MANUFACTURING PROCESSES FOR HIGH VOLUME PRODUCTION (possibly in partnership with larger manufacturing corporation)

41. QUESTIONS? DR. ERIC WALTON OSU ELECTROSCIENCE Walton.1@osu.edu
Dr. Eric K. Walton
The Ohio State Univ. ElectroScience Lab
Columbus, OH;