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

tkwu48@gmail.com

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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