Modeling Multiple Printed Antennas Embedded in Stratified Uniaxial Anisotropic Dielectrics Ph.D....

Modeling Multiple Printed Antennas Modeling Multiple Printed Antennas Embedded in Stratified Uniaxial Embedded in Stratified Uniaxial

Anisotropic DielectricsAnisotropic Dielectrics

Ph.D. Candidate:Ph.D. Candidate:Benjamin D. BraatenBenjamin D. Braaten

Electrical and Computer EngineeringElectrical and Computer EngineeringNorth Dakota State UniversityNorth Dakota State University

February 6February 6thth, 2009, 2009

TopicsTopics

IntroductionIntroduction The printed antenna. The printed antenna. Properties and applications.Properties and applications.

Proposed researchProposed research Derivation of the new spectral domain immittance Derivation of the new spectral domain immittance

functions.functions. Solving the new spectral domain immittance functions.Solving the new spectral domain immittance functions. Numerical results and measurements.Numerical results and measurements. Future work.Future work. Conclusion.Conclusion.

North Dakota State UniversityNorth Dakota State University

IntroductionIntroduction

In 1953 Deschamps In 1953 Deschamps formally introduced formally introduced the microstrip the microstrip antenna [1].antenna [1].

Many uses:Many uses: RadarRadar Cellular comm.Cellular comm. Satellite comm.Satellite comm. Wireless networksWireless networks Wireless sensorsWireless sensors Biomedical devicesBiomedical devices RFID …RFID …

North Dakota State UniversityNorth Dakota State University[1] G. A. Deschamps, “Microstrip Microwave Antennas,” 3rd USAF Symposium on Antennas, 1953.


Disadvantages:Disadvantages: Many designs have a Many designs have a

narrow bandwidthnarrow bandwidth Radiate into a half spaceRadiate into a half space Poor endfire radiationPoor endfire radiation Poor isolation between Poor isolation between

the feed an radiating the feed an radiating elementselements

Possible surface waves Possible surface waves (power loss)(power loss)


Advantages:Advantages: Low profileLow profile LightweightLightweight Low costLow cost Able to achieve UWB Able to achieve UWB

(in some cases)(in some cases) Dual frequency Dual frequency

capabilitiescapabilities Simple to fabricateSimple to fabricate



Region between plates act like the region between a transmission line and a ground plane with both ends open.

Results in a standing wave.

Fringing fields are responsible for radiation.



Properties of interest include:Properties of interest include: Input impedanceInput impedance Current distributionCurrent distribution Radiation patternsRadiation patterns BandwidthBandwidth Feed techniques Feed techniques Mutual coupling with other Mutual coupling with other

elementselements Conducting patch layout Conducting patch layout … … etc.etc.


Many different types of layoutsMany different types of layoutsexist:exist:


[3] H. Wang, X. B. Huang and D. G. Fang, “A single layer wideband U-slot microstrip patch antenna array,” IEEE Antennas and Wireless Propagation Letters, vol. 7, 2008, pp. 9-12.

[3]

[2] Anthony Lai and Tatsou Itoh, “Composite Right/Left Handed Transmission Line Metamaterials,” IEEE Magazine, September 2004.

[2]

Proposed ResearchProposed ResearchConsider:Consider:


Proposed ResearchProposed Research


RESEARCH QUESTIONS:RESEARCH QUESTIONS:What is the input impedance of a driven element in the What is the input impedance of a driven element in the

layered anisotropic structure in the presence of layered anisotropic structure in the presence of other conducting patches defined on arbitrary other conducting patches defined on arbitrary anisotropic layers in the same structure?anisotropic layers in the same structure?

andand What is the mutual impedance between a driven What is the mutual impedance between a driven

element in the layered anisotropic structure and element in the layered anisotropic structure and other conducting patches defined on arbitrary other conducting patches defined on arbitrary anisotropic layers in the same structure?anisotropic layers in the same structure?

Proposed ResearchProposed Research


The previous two questions are very significant in The previous two questions are very significant in many fields. many fields. Microstrip antenna arrays [4].Microstrip antenna arrays [4]. Frequency Selective Structures (FSS) [5]Frequency Selective Structures (FSS) [5] Radio Frequency Identification (RFID) [6]Radio Frequency Identification (RFID) [6] IC based antennasIC based antennas Radar …Radar …

[4] David M. Pozar and Daniel H. Schaubert, “Microstrip Antennas: The analysis and Design of Microstrip Antennas and Arrays”, IEEE Press, Piscataway, NJ, 1995.

[5] A.L.P.S. Campos an A.G. d'Assuncao, “Scattering paramters of a frequnecy selective surface between anisotropic dielectric layers for incidnet co-polarized plane waves,” IEEE Antennas and Propagation Society International Symposium, 2001, Vol. 4, July 8-13, 2001, p. 382-385.

[6] K. Finkenzeller, RFID Handbook:Fundamentals and Applications in Contactless Smart Cards and Identification, John Wiley and Sons, West Sussex, England, 2003.

The new spectral domain immittance The new spectral domain immittance functionsfunctions


Start with the following Hertz vector potentials:Start with the following Hertz vector potentials:

andand

Electric Hertz Electric Hertz potentialpotential

Magnetic HertzMagnetic Hertzpotentialpotential



Next, only the y-direction of the Hertz vector Next, only the y-direction of the Hertz vector potential is needed.potential is needed.

andand

This is because the optical axis is in the y-This is because the optical axis is in the y-direction direction

and and this component satisfies the higher order TE this component satisfies the higher order TE

and TM tangential boundary conditions.and TM tangential boundary conditions.

Numerical results and measurementsNumerical results and measurements


The TEM, TM and TE modesThe TEM, TM and TE modes

[9] http://www.ibiblio.org/kuphaldt/electricCircuits/AC/02407.png

[9]

TEM modeTEM mode

TM and TE modesTM and TE modes



Now define the following expression for the magneticNow define the following expression for the magneticand electric field:and electric field:

where the Hertzian vector potentials are solutions to where the Hertzian vector potentials are solutions to the following wave equations:the following wave equations:



andand



To simplify evaluating the previous expressions, we To simplify evaluating the previous expressions, we define the following Fourier transform:define the following Fourier transform:

This results in the following relations:This results in the following relations:



This results in the following simplified expressions:This results in the following simplified expressions:

wherewhere

andand



Similarly forSimilarly for

andand



Single layer problemSingle layer problem




Now use these expressions Now use these expressions to enforce the boundary to enforce the boundary conditions:conditions:




After extensive factoring and manipulation, the following After extensive factoring and manipulation, the following spectral domain immittance functions are derived:spectral domain immittance functions are derived:

andand

wherewhere

(typical(typical expression – expression –

spectral spectral domaindomainGreen’s Green’s function)function)



Double (dDouble (d33 = 0) and Triple layer problems = 0) and Triple layer problems



Double and Triple layer problemsDouble and Triple layer problems

After extensive factoring and manipulation, the following After extensive factoring and manipulation, the following spectral domain immittance functions are derived:spectral domain immittance functions are derived:

andand

Solving the new expressionsSolving the new expressions


The spectral domain The spectral domain moment method was moment method was used to solve for the used to solve for the unknown current.unknown current.

PWS functions were PWS functions were used as expansion and used as expansion and basis functions.basis functions.

A delta source was A delta source was used to drive the used to drive the problem.problem.



The problem chosen to validate newly derived spectral The problem chosen to validate newly derived spectral domain immittance functions was the printed dipole.domain immittance functions was the printed dipole.



The first step was toThe first step was tovalidate the numericalvalidate the numericalresults with experimental results with experimental measurements.measurements.

Radius a = 0.4 mmRadius a = 0.4 mm Length L = 60 mmLength L = 60 mm FR-4: FR-4: εεrr = 4.35 = 4.35 Printed strip W = 4aPrinted strip W = 4a



Picture of measured monopole.Picture of measured monopole.



This resulted in the following measured resonant This resulted in the following measured resonant frequencies:(Epsilam-10: and ,frequencies:(Epsilam-10: and ,

Rogers 5880: Rogers 5880: ) )



Single layer resultsSingle layer results




L = 15 mmL = 15 mmW = 0.5 mmW = 0.5 mmdd11 = 1.58 mm = 1.58 mm

Notice the y-Notice the y-component has thecomponent has themost effect on themost effect on theresonant frequency resonant frequency

(TM(TM00 mode). mode).



Single layer resultsSingle layer results The TEM, TM and TE mode reminderThe TEM, TM and TE mode reminder

[9] http://www.ibiblio.org/kuphaldt/electricCircuits/AC/02407.png

[9]

TM and TE modesTM and TE modesA quick illustration A quick illustration of the TMof the TM00 mode. mode.










L = 15 mmL = 15 mmW = 0.5 mmW = 0.5 mmf = 500 MHzf = 500 MHzdd11 = 1.58 mm = 1.58 mmNotice:TMNotice:TM00 has hasthe most effectthe most effect(i.e. y-compontent(i.e. y-compontentof the permittivityof the permittivity



Double layer resultsDouble layer results




L = 15 mmL = 15 mmW = 0.5 mmW = 0.5 mmdd11 = 1.58 mm = 1.58 mmdd22 = 1.58 mm = 1.58 mm

εε11= = 2.552.55

Notice: Notice: εεxx22 affects affects

the resonant the resonant frequency the frequency the most.most.




The field lines:The field lines:




L = 15 mmL = 15 mmW =0 .5 mmW =0 .5 mmdd11 = 1.58 mm = 1.58 mm

εε11= = 2.552.55

region 2: anisotropicregion 2: anisotropic




L = 15 mmL = 15 mmW = 0.5 mmW = 0.5 mmf = 500 MHzf = 500 MHzdd11 = 1.58 mm = 1.58 mmdd22 = 1.58 mm = 1.58 mm

εε11= = 3.25.3.25.




(Single layer results)(Single layer results)




L = 15 mmL = 15 mmW = 0.5 mmW = 0.5 mmf = 500 MHzf = 500 MHzdd11 = 1.58 mm = 1.58 mmdd22 = 1.58 mm = 1.58 mm

εε11= = 3.25.3.25.






Triple layer resultsTriple layer results

L = 15 mmL = 15 mmW = 0.5 mmW = 0.5 mmf = 500 MHzf = 500 MHzdd11 = 1.58 mm = 1.58 mmdd22 = 1.58 mm = 1.58 mmdd33 = 1.58 mm = 1.58 mm

εε11= ε= ε22= = 3.25.3.25.



Triple layer resultsTriple layer results(Double layer results)(Double layer results)

ConclusionConclusion


New spectral domain immittance functions New spectral domain immittance functions have been derived.have been derived.

The new spectral domain immittance The new spectral domain immittance functions have been validated with functions have been validated with measurements, published literature and measurements, published literature and commercial software.commercial software.

One, two and three layer problems have One, two and three layer problems have been investigated.been investigated.



The following has been shown: The following has been shown: The permittivity in the direction of the optical axis The permittivity in the direction of the optical axis

below the printed dipole has the most impact on below the printed dipole has the most impact on the resonant frequency.the resonant frequency.

The layer thickness values eventually have little The layer thickness values eventually have little effect on the resonant frequency.effect on the resonant frequency.

The permittivity in the direction of the optical axis The permittivity in the direction of the optical axis above printed dipoles has little or no effect on the above printed dipoles has little or no effect on the mutual coupling.mutual coupling.

The permittivity in the direction orthogonal to the The permittivity in the direction orthogonal to the optical axis in the layers above the dipoles can be optical axis in the layers above the dipoles can be used to control the mutual coupling.used to control the mutual coupling.



Future workFuture work Investigate coupling between rectangular Investigate coupling between rectangular

microstrip antennas in layered anisotropic diel.microstrip antennas in layered anisotropic diel. Investigate coupling between UWB antennas in Investigate coupling between UWB antennas in

layered anisotropic diel.layered anisotropic diel. Investigate how anisotropic materials could be Investigate how anisotropic materials could be

used to control coupling between RFID tagsused to control coupling between RFID tags IC based antennasIC based antennas Metamaterial based designsMetamaterial based designs Mathematical aspectsMathematical aspects

polespoles surface wave modessurface wave modes convergenceconvergence

QuestionsQuestions


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Modeling Multiple Printed Antennas Embedded in Stratified Uniaxial Anisotropic Dielectrics Ph.D....

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