Forum for Electromagnetic Research Methods and Application Technologies (FERMAT)
MTM Filter with Split-Ring-Resonator (SRR) Elements for Phased Array
By
T.K. Wu
FSS and Antenna Consulting
Rancho Palos Verdes, CA, USA
Abstract: A single thin-screen metamaterial (MTM) filter with split-ring-resonator (SRR)
elements was proposed and demonstrated to block the higher-order harmonics of a K-band phased
array (operating between 20.2 and 21.2 GHz) spilling into a close-by astronomic-band (from 22.21
to 22.5 GHz). It also provided at least 22-dB attenuation in the stop-band. In addition, this MTM
filter can be very inexpensively fabricated by the modern printed wiring board (PWB) technique
and mounted on top of the radiating aperture of a phased array with thousands of elements.
Keywords: Compact Metamaterial Filter, Split-Ring-Resonator, Phased Arrays.
Reference:
[1] H. Rosen, “Frequency selective screen having sharp transition,” US Patent # 4,785,310,
Nov. 15, 1988.
[2] T.K. Wu, “Improved dual band FSS performance with fractal elements,” Microwave and
Optical Tech. Lett., vol. 54, no. 3, pp. 833-835, March 2012.
[3] T.K. Wu, “Low-cost and frequency-selective metamaterial and its antenna applications,”
2015 Antenna Systems Conference, Las Vegas, Nov. 5-6, 2015.
[4] S. Monni, A. Neto, G. Gerini, F. Nennie, and A. Tijhuis, “FSS to prevent interference
between radar and SATCOM antennas,” IEEE AWPL, vol. 8, pp. 220-223, 2009.
[5] M. Moallem and K. Sarabandi, “A spatial image rejection filter based on miniaturized
element FSS for J-band radar applications,” 2012 IEEE Int. Symp. Antennas and Propag., Chicago,
IL, 2012.
[6] T.K. Wu, “Low-cost and high performance quasi-optical filter for phased arrays,” 2013
IEEE Int. Symp. Antennas and Propag./ USNC-URSI, Orlando, FL July 2013.
[7] F. Costa, S. Genovesi, A. Monorchio, and G. Manara, “A circuit-based model for the
interpretation of perfect metamaterial absorbers,” IEEE Trans., AP-61, no. 3, pp. 1201-1209,
March 2013.
[8] W.J. Padilla, et. al., “Electrically resonant terahertz metamaterials: theoretical and
experimental investigations,” Phys. Rev. B, 75, pp. 041102-1 to -4, 2007.
[9] H. Tao, et. al., “Highly flexible wide angle of incidence terahertz metamaterial absorber:
design, fabrication, and characterization,” Physical Review B, 78, pp. 241103-1 to -4, 2008.
[10] N.I. Landy, et. al., “Perfect metamaterial absorber,” Phys. Rev. Lett., vol. 100, pp. 207402-
1 to -4, 2008.
[11] T.K. Wu, “Novel metamaterial absorber with fractal elements,” Proc. IEEE Int.
Symposium on Antenna and Propagation, Vancouver, Canada, pp. 244-245, July 2015.
[12] C.L. Holloway, et. al., “An overview of the theory and applications of metasurfaces: the
two-dimensional equivalents of metamaterials,” IEEE Antennas and Propagation Magazine, vol.
54, no. 2, pp. 10-35, April 2012.
[13] T.K. Wu, J. Macek, and M. Bever, “Frequency selective surface (FSS) filter for an
antenna,” US Patent # 5,949,387, Sept. 7, 1999.
[14] C.K. Lee and R. Langley, “Equivalent circuit models for frequency selective surfaces at
oblique angle incidence,” IEE Proc., part H, Microwaves, Antennas, Propag., vol. 132, #6, pp.
395-398, 1985.
[15] T.K. Wu and S. Puri, “Precision multi-layer grids fabrication techniques,” US Patent #
6,396,451 B1, May 28, 2002.
*This use of this work is restricted solely for academic purposes. The author of this work owns the copyright and no reproduction in any form is permitted without written permission by the author. *
1. M.S. and Ph.D. degree in Electrical Engineering from University of Mississippi in 1973 and 1976, respectively.
2. 46 years’ professional experience as the Research & Development Engineer of Antennas, FSS, and Electromagnetics in JPL, Hughes, Northrop Grumman Aerospace Companies.
3. Published more than 200 technical papers, 27 U.S. patents, 1 book, and 2 book chapters.
4. Awarded fourteen NASA Certificates of Recognition for technical innovation.
5. Senior member of IEEE Antennas and Propagation Society.
6. Reviewer for IEEE Trans., AWPL, IET, Radio Science, AEU, PIER, …, etc.
MTM Filter with Split-Ring-Resonator (SRR) Elements for Phased Array
T.K. Wu
June 2016
Overview
• Introduction and earlier publications
• Split-ring resonator meta-surface structure
• Sharp transition Frequency Selective Surface
• Advantages of quasi-optical grids
• Equivalent Circuit Model (ECM)
• Simulation results and validation
• Conclusion
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Fig. 1a Transmission Characteristics of Frequency Selective Screen (FSS)
Rejection Band
Band Separation Ratio = Freq (High-band)/ Freq (Low-band) = Fh/FL
3 Copyright © 2014 T.K. Wu July 7, 2014
TK Wu, FSS and Grid Array, Chap. 1, Wiley, 1995
T
Low Band
High Band
Fh FL
Pass Band Rejection Band 1
0
F
T
Low Band
High Band
Fh FL
Pass Band 1
0
F
Low Pass Filter/Diplexer High Pass Filter/Diplexer
Figure 1c Configuration of an Array/Antenna with an Aperture Mounted FSS Filter/Shield
FSS Filter
Spacer
Horns
Amplifiers
Array/ Antenna
Feb 2014 Copyright © 2014 T.K. Wu 4
Quasi-Optical Grids for Interference Filter Filter
FSS Element
Waveguide Element Phased Array
S. Monni, et. al., IEEE AWPS, 8, 220-223, 2009
Pass-band: 8-10 GHz Stop-band: 10.8-11.4 GHz 10 dB Rejection in Stop-band
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Quasi-optical Grids for Image Rejection
M. Moallem & K. Sarabandi, IEEE Int. AP Symposium, Chicago, IL, 2012
Pass-band: 221-223 GHz Stop-band: 206-208 GHz Fh/Fl = 221/208 = 1.06 25dB Rejection in Stop-band
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Split-ring resonator meta-surface structure
C.L. Holloway, et. al., IEEE APS Magazine, 54, 10-35, April 2012
Pass-band: 3.55 GHz Stop-band: 3.3 GHz Fh/Fl = 3.55/3.3 = 1.076
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SRR Reflection vs Incident Angle
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C.L. Holloway, et. al., IEEE APS Magazine, 54, 10-35, April 2012
SRR Filter’s Equivalent Circuit Model
Input Admittance Y = 1/[1/(1/X2 +1/(X1 -1/B1))-1/B2]
X1 = jωL1
X2 = jωL2
B1 = jωC1 B2 = jωC2
ω = 2πf
SRR slots etched on copperOn a 1 mil thick Kapton
1. N. Marcuvitz, Waveguide Handbook, N.Y., McGraw-Hill, 1951 2. F. Costa, et. al., IEEE AP Magazine, 54, 35-48, August 2012
T = 1/[1+0.25 Y2]0.5
Copper etched on Thin Substrate
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Relation between Patch and Slot FSS
• From duality principle, for any complimentary slot and patch element FSS,
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T slot element = R patch element
R slot element = T patch element
REFLECTION PERFORMANCE Verification OF HIGH Q SPLIT RING FSS
-40
-35
-30
-25
-20
-15
-10
-5
0
2.5 2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5 4.7 4.9 5.1 5.3 5.5
Re
fle
ctio
n (d
B)
Frequency (GHz)
ECM PREDICTED FSS RESPONSE AGREES WITH HOLLOWAY’S RESULTs
Fh /Fl = 3.55/3.3 = 1.076 1.1-cm Cell Size
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ECM x x x Holloway’s
x x x
x
x x
x x
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Filter Performance with Split Ring Resonator (SRR) Slot Elements
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SRR slots etched on copper On a 1 mil thick Kapton
Fh/FL = 22.21/21.2 = 1.05
-40
-35
-30
-25
-20
-15
-10
-5
0
19 19.5 20 20.5 21 21.5 22 22.5 23
Tra
nsm
issio
n (
dB
)
Frequency (GHz)
pass band
stop band
Stable performance w.r.t. incident angles
P
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Conclusion
• Described the sharp transition Split-Ring FSS – Fh/FL no bigger than 1.05
• Described and verified the ECM approach for simulating SRR FSS performance
• Demonstrated the SRR filter features – Low mass and low volume
– Easy mounting/integration in the front-end of a phased array antenna
– Low fabrication cost especially for a large array with thousands of radiating elements
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