forum for electromagnetic research methods and …€¦ · 2015), lisbon, portugal, apr ... he was...

Forum for Electromagnetic Research Methods and Application Technologies (FERMAT)

Systematic Approach for Electrically Tuning N-port Antenna System Based on Characteristic Modes

Montaha Bouezzeddine, Werner L. Schroeder

RheinMain University of Applied Sciences, GERMANY

EUCAP 2016, April 11, 2016, Davos

Abstract: We develop, in this paper, a systematic approach to be applied for matching/tuning N-port symmetric antenna system whose design is based on the characteristic modes of a device. The approach uses conformal mapping techniques and allows us to study the feasibility and possible implementation of a “joint matching” to simultaneously match several radiation modes. The approach helps to conclude about the available modes that could be physically matched and to decide about possibly making some amendments on the antenna design. It renders the tuning range of elements of the tunable matching network.Theoretical derivation is supported by the measured scattering parameters of a MIMO antenna system operating in the range[470; 790] MHz.

Keywords:

MIMO, characteristic modes, radiation modes, conformal mapping, tunable matching, isolation, antenna measurements, tuning states optimization, Microcontroller.

REFERENCES 1. Z. H. Hu, P. Hall, P. Gardner, and Y. Nechayev, “Wide tunable balanced antenna for mobile terminals and its potential for MIMO applications,” in Antennas and Propagation Conference (LAPC), 2011 Loughborough, Nov 2011, pp. 1–4. 2. J.-H. Lim, Z.-J. Jin, C.-W. Song, and T.-Y. Yun, “Simultaneous frequency and isolation reconfigurable MIMO PIFA using PIN diodes,” Antennas and Propagation, IEEE Transactions on, vol. 60, no. 12, pp.5939–5946, Dec 2012. 3. Z. Miers, H. Li, and B. K. Lau, “Design of bandwidth-enhanced and multiband MIMO antennas using characteristic modes,” Antennas and Wireless Propagation Letters, IEEE, vol. 12, pp. 1696–1699, 2013. 4. A. Krewski, W. Schroeder, and K. Solbach, “MIMO LTE antenna design for laptops based on theory of characteristic modes,” in Antennas and Propagation (EUCAP), 2012 6th European Conference on, March 2012, pp. 1894–1898. 5. S. Chaudhury, H. Chaloupka, and A. Ziroff, “Novel MIMO antennas for mobile terminal,” in Microwave Conference, 2008. EuMC 2008. 38th European, 2008, pp. 1751–1754. 6. R. Martens, E. Safin, and D. Manteuffel, “Selective excitation of characteristic modes on small terminals,” in Antennas and Propagation (EUCAP), Proceedings of the 5th European Conference on, April 2011, pp. 2492–2496. *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.*

7. M. Bouezzeddine and W. L. Schroeder, “‘Wideband decoupling and tunable matching networks for multi-port antennas,” in The 8th European Conference on Antennas and Propagation (EuCAP 2015), Lisbon, Portugal, Apr. 2015, pp. 3169–3173. 8. S. Stein, “On cross coupling in multiple-beam antennas,” Antennas and Propagation, IRE Transactions on, vol. 10, no. 5, pp. 548–557, September 1962. 9. W. Kahn, “Active reflection coefficient and element efficiency in arbitrary antenna arrays,” Antennas and Propagation, IEEE Transactions on, vol. 17, no. 5, pp. 653–654, Sep 1969. 10. M. Thompson and J. Fidler, “Determination of the impedance matching domain of impedance matching networks,” Circuits and Systems I: Regular Papers, IEEE Transactions on, vol. 51, no. 10, pp. 2098–2106, Oct 2004.

Montaha Bouezzeddine: was born in Brih ElChouf- Lebanon. She received her engineering diploma in Networks and Communication Systems from the National Institute of Applied Sciences (INSA), France, in 2012. Since 2012, she is working as a research engineer at RheinMain University of Applied Sciences, Rüsselsheim - Germany, in the field of multiport antenna systems for cognitive radio. She is currently working toward the PhD degree. Her research interests include MIMO antennas, tunable and reconfigurable antennas, characteristic modes theory, and adaptive tuning and digital control. She was the recipient of the Best student paper award at EUCAP 2016.

Werner L. Schroeder: received the Dipl.-Ing. degree in electrical engineering in 1986 and the Dr.-Ing. degree in 1993, both from Duisburg University, Duisburg Germany. From 1986 to 1999, he was with the Department of Electromagnetic Theory at Duisburg University working on numerical methods for electromagnetic field analysis and physics based simulation of electronic transport in compound semiconductors. In 1999, he joined Infineon Technologies AG, Germany, where he worked as product group leader for the Radio Frequency Identification and Contact-less Chip Card segment. From 2001 to 2006, he worked with the Technology and Innovations department of Siemens Communications / Mobile Phones, Germany, where he was in charge of a major research project on

Software Defined Radio for mobile devices. Since 2008, he is a Professor at RheinMain University of Applied Sciences in Rüsselsheim, Germany. His current research interests include Over-The-Air characterization of mobile devices, multi-port antenna systems for mobile communications and wideband antenna / frontend architectures.

Systematic Approach for Electrically Tuning N-portAntenna System Based on Characteristic Modes

Montaha Bouezzeddine, Werner L. Schroeder

RheinMain University of Applied Sciences, GERMANY

EUCAP 2016, April 11, 2016, Davos

M. Bouezzeddine, W. Schroeder (HSRM) Tuning of Antenna systems based on CMs 2016-04-11 1 / 29

Outline

1 Introduction

2 What to match at coupler ports

3 Procedure for Simultaneous Matching of Modes

4 Application and Results

5 Conclusion


Introduction

Outline

1 Introduction




5 Conclusion


Introduction

Some designs of MIMO antennas based on CMs

Superposition of CMs[Lund]

ICE11

ICE12

ICE21

Selective excitation [Kiel]

CC4

CC3

CC1

CC2

Joint excitation[this work]

MIMO antenna solution depends on:Chassis shape (handheld, CPE, laptop,...)

Number of antennas

Frequency range (narrowband,tunable/reconfigurable)

Instantaneous Bandwidth (BW)


Introduction

Symmetric Multiport antenna

A multiport antenna is called symmetric if its scattering matrix, SA,remains unchanged after a permutation of port indices, i.e.

PSAP = SA

P, permutation matrix, and SA have a common basis of eigenvectors.

Matrix of radiation modes, V, verifies:

V>V = I

Implication of symmetryThe symmetry property with respect to S-matrix leads to frequencyindependent radiation modes and simplifies the design of DecouplingNetwork (DN).


Introduction

Comparison of Multi-port Matching approachesSM SD

(a)

......

...

1

2

N

1

2

N

(b)

SD SM

......

...

+ Match each mode individually

− Degradation of DN performancebecause of mismatch

− Practicality of MatchingNetwork (MN) design

− Increase of losses

+ Higher modal efficiencies

+ Suitable for widebandapplication

+ Post-matching is possible

− Trade-off matching solution


Introduction

How to match simultaneously different Modes?

0.2 0.5 1 2 50

0.2

0.5

1

2

5

−0.2

−0.5−1

−2

−5

Γ1

Γ2

Γ3

Γ4

6 dB

RL circleApplication subject to the condition

|Γi − Γj| < dmin

Γ: modal reflectance of agiven radiation mode

But ...Up to which difference level?


What to match at coupler ports

Outline

1 Introduction




5 Conclusion


What to match at coupler ports

Matching at couplers in N-port symmetric antennaSM SD

ΓΓ SA

(a)

......

...

1

2

N

(b)1

2

N

SD SM

SAΓ SA

......

...

V>V = I, Γ = V>SAV, SD =

(0 V

V> 0

), and SM =

(sM11I sM12IsM21I sM22I

)

PropositionUnder the stated condition on permutations of an N-port symmetricantenna system, matching at coupler ports is equivalent to applyingthe same matching to each single mode .


Procedure for Simultaneous Matching of Modes

Outline

1 Introduction




5 Conclusion



Simultaneous Matching of N-modes

0.2 0.5 1 2 50

0.2

0.5

1

2

5

−0.2

−0.5

−1

−2

−5

Γ1

Γ2

Γ3

Γ4

6 dBRL circle

Match the N modessimultaneously to agiven return loss level

Modal reflectances varyover frequency

Tunability is required fora wide frequency range



Step I: Feasibility CriterionLossless and reciprocal 2-port MN

sM11 = r e jφ1 , sM22 = r e jφ2

sM11

sM21

sM12

sM22 ΓΓ→

modal reflectanceat antenna ports

modal reflectanceat feed ports

Γ e− jφ1 = F (Γ e jφ2)

Γ e jφ2 = F (Γ e− jφ1)

F (z) :=r − z1− rz

F (z) is a Mobius transformationand is equal to its own inverse

F (Γ e− jφ1)⇓

Mapping circles to circles



Load and Matchable zone parameters

...........................................................................

.....................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................

...................................................................................................................................................................................

.............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................•C

R

..........

................

.............

.............

..........................

........................................................................................................

.................................................................

.......................... ............. ............. ............. ............. ............. .............

..........................

.........................................•

ρ

Mapping of a load in the SMITH -Chart to a circle of the minimumrequired return loss

C: distance (SMITH-Chart center -matchable circle center)

R: Radius of matchable circle



Matching Limitations

Result: −R2 + C2 +R

(1

ρ+ ρ

)− 1 = 0

0.0 0.2 0.4 0.6 0.8 1.0

distance of circle center from origin C −→

0.0

0.1

0.2

0.3

0.4

0.5

0.6

circ

lera

dius

R−→

...................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................

6 dB return loss

....................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................

8 dB

...............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................

10 dB

......................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................

15 dB...........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................

20 dB



Present example, modal reflectances of 4 modes

0.2 0.5 1 2 50

0.2

0.5

1

2

5

−0.2

−0.5−1

−2

−5

Γ0

Γ1

Γ2

Γ3

Γ4

Γ0 = s∗M22

sM22 results from theoptimization of MN forthe 4 modes

Simultaneous matchingis not feasible for 4modes.



Present example, modal reflectances of 3 modes

0.2 0.5 1 2 50

0.2

0.5

1

2

5

−0.2

−0.5−1

−2

−5

Γ0

Γ1

Γ2

Γ3

Γ0 = s∗M22

sM22 results from theoptimization of MN forthe 3 modes

Simultaneous matchingis feasible for 3 modes.



Step II: Matching network specificationInput: Modal reflectances in theconsidered frequency range

Optimization criterion: Minimization

Root Mean Square (RMS) ofmodal reflectances

∣∣∣ΓRMS(f)∣∣∣2 :=

1

N

N∑n=1

∣∣∣Γn(f)∣∣∣2

=1

N

N∑n=1

F(Γn(f) e jφ2(f)

)

Output: Frequency dependentscattering matrix of MN

0.5 0.55 0.6 0.65 0.7 0.750

0.2

0.4

0.6

0.8

1

frequency/GHz

r0.5π

π

1.5π

2π

φ2/

rad

rφ2

Optimum parameters (r, φ2)over frequency



Step III: Topology of 2-port Matching Network

Step III: Find the Topology of 2-port Matching Network

Determination of MN topology from the locus of “average” modalreflectance Γ0 in the SMITH-Chart.

0.1 0.2 0.3 0.4 0.5 1 1.5 2 3 4 5 10 200

0.1

0.2

0.3

0.4

0.5

0.6 0.

7 0.8 0.9 1

1.5

2

3

4

5

10

20

−0.1

−0.2

−0.3

−0.4

−0.5

−0.6

−0.7

−0.8

−0.9

−1

−1.5

−2

−3

−4−5

−10

−20

1

forbiddenregion

6 dB

circle

ZL



Step IV: Tuning Elements

Step IV: Determine the Range of Tunable Elements

Optimum s-parameters of the MN for the chosen topology.

Determination of tuning range of tunable elements.

0.45 0.5 0.55 0.6 0.65 0.7 0.75 0.80

5

10

15

20

25

frequency/GHz

Ser

ies

Cap

acita

nce/

pF

0

2

4

6

8

10

12

14

16

Shu

ntC

apac

itanc

e/p

F

SeriesShunt

CMOSdriver

RF + RF -

SerialInterface

[Peregrine semiconductor]


Application and Results

Outline

1 Introduction




5 Conclusion



Hardware Realization

overall assembly

tunablematchingnetwork

(5×)

decouplingnetwork



Hardware-in-the-loop optimization

decouplingnetwork

µC

4-port VNA

RF lines

SPI

USB

LAN

DTC

Find Final tuning tables for 40× 40 Time-Division Duplex (TDD) andFrequency-Division Duplex (FDD) channels by a hardware-in-the-loopoptimization



Measurement Results - TDD scenario

.......

.......

..............................................................

........................

...................................................................................................................................................................................................................................................................................................................................................................

..........................................................................................................

Γ2

................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................

.....................................................................................................

....................................................................................................................................................

.................................................................................................................................................................................................................................................................................................................................................................................................................................

•

•

•

•

•

Γ3

...........................................................

........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................

...........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................• •

••

•

markers at {470,550,630,710,790} MHz

Measured reflectance over 40bands of 8 MHz each

Tuning applied separately ineach band

Most segments inside 6 dBreturn loss circle



Measurement Results - FDD scenarioRMS return loss over all 4 modes for 40× 40 pairs of 8MHz RX/TX channels

474 538 602 666 730 786

TX channel center frequency in MHz −→

474

538

602

666

730

786

RX

chan

nelc

ente

rfre

quen

cyin

MH

z−→

0

1

2

3

4

5

6

7

8

9

10

RM

Sre

turn

loss

dB



Measurement Results - FDD scenarioMinimum TX to RX isolation at TX frequencyfor 40× 40 pairs of 8MHz RX/TX channels

474 538 602 666 730 786

TX channel center frequency in MHz −→

474

538

602

666

730

786

RX

chan

nelc

ente

rfre

quen

cyin

MH

z−→

20

22

24

26

28

30

32

34

36

38

40

min

imum

isol

atio

n

dB


Conclusion

Outline

1 Introduction




5 Conclusion


Conclusion

Conclusions

Study the feasibility of simultaneous matching of modes sharingthe same couplers

Use conformal mapping techniques to help designing the TunableMatching Network (TMN)

Measurement results back the theoretical derivations

Complexity of TMN depends on the difference of the modalimpedances


Conclusion

Conclusions

Study the feasibility of simultaneous matching of modes sharingthe same couplers

Use conformal mapping techniques to help designing the TMN

Measurement results back the theoretical derivations

Complexity of TMN depends on the difference of the modalimpedances


Abbreviations

Abbreviations I

CM Characteristic Mode

CMOS Complementary Metal-Oxide-Semiconductor

DTC Digitally Tunable Capacitor

FDD Frequency-Division Duplex

MIMO Multiple Input – Multiple Output

TDD Time-Division Duplex


Abbreviations

THANKS FOR YOURATTENTION !


forum for electromagnetic research methods and …€¦ · 2015), lisbon, portugal, apr ... he was...

Documents