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Advances in the Formulations and Accuracy of theMethod of Moments Applied to Electromagnetics

Thierry Gilles 1, Marc Piette 2, Christophe Craeye3

1,2 Ecole Royale Militaire, Laboratoire d’Electromagnétisme Appliqué (LEMA)Avenue de la Renaissance 30, 1000 Bruxelles, Belgium

thierry.gilles@rma.ac.be , marc.piette@rma.ac.be

3 Université catholique de Louvain, Laboratoire TELEPlace du Levant 2, 1348 Louvain-la-Neuve, Belgium

craeye@uclouvain.be

Advances in the Formulations and Accuracy of theMethod of Moments Applied to Electromagnetics

1. INTRODUCTION

2. EXACT THEORY

3. METHOD OF MOMENTS

4. MIXED MATERIALS

5. E-MFIE for EMBEDDED SHEETS

6. ACCURACY

7. CONCLUSIONS

OUTLINE

Advances in the Formulations and Accuracy of theMethod of Moments Applied to Electromagnetics

INTRODUCTION

Far Field

Advances in the Formulations and Accuracy of theMethod of Moments Applied to Electromagnetics

INTRODUCTION

Advances in the Formulations and Accuracy of theMethod of Moments Applied to Electromagnetics

INTRODUCTION

45m

Advances in the Formulations and Accuracy of theMethod of Moments Applied to Electromagnetics

INTRODUCTION

Near Field..differences..

Advances in the Formulations and Accuracy of theMethod of Moments Applied to Electromagnetics

INTRODUCTION

Mobile phone dual band antenna

Advances in the Formulations and Accuracy of theMethod of Moments Applied to Electromagnetics

INTRODUCTION

Benchmarking of software tools for small planar antenna analysisGuy A. E. Vandenbosch(1), A. Vasylchenko(1,2), and W. De Raedt(2)

Conference iWAT 2010

Impedance..differences..

Advances in the Formulations and Accuracy of theMethod of Moments Applied to Electromagnetics

INTRODUCTION

H

E

Advances in the Formulations and Accuracy of theMethod of Moments Applied to Electromagnetics

INTRODUCTION

Total Ez Field

Reaction to an EM excitation

by a set of LinearHomogeneousIsotropic

Volumes and/or Sheets

with bounding closed surface Sj

RESOLUTION METHOD : Maxwell EFIEi / MFIEi MoM Ji,Mi

Advances in the Formulations and Accuracy of theMethod of Moments Applied to Electromagnetics

INTRODUCTION

Advances in the Formulations and Accuracy of theMethod of Moments Applied to Electromagnetics

EXACT THEORY

0 0 0

0 0 0

0 0

0 , 0

.

.

source

source

source

m source

E j H M

H j E J

E

H

Harmonic waves ( ejt )

Advances in the Formulations and Accuracy of theMethod of Moments Applied to Electromagnetics

EXACT THEORY

EFIE – MFIE

0 0 0

0 0 0

0 0

0 , 0

.

.

source

source

source

m source

E j H M

H j E J

E

H

S1V

V0

0n̂

0 0 0 0 0 0 0 0 0 0 0ˆ ˆ ˆ( ) ( ) ' . ' 'inc

SE r E r j G n H n E G n E G dS

0 0 0 0 0 0 0 0 0 0 0ˆ ˆ ˆ( ) ( ) ' . ' 'incS

H r H r j G n E n H G n H G dS

S2

Advances in the Formulations and Accuracy of theMethod of Moments Applied to Electromagnetics

EXACT THEORY

EFIE – MFIE

EFIE :

MFIE :

From Differentialto

Integral equations

r

S1b

S2a

S3b

S4b

S4a

V0

1 ˆ ˆ ˆ( ) ( ) ( ) ' ' '2 a b

inca b S S

E r E r E r j G n H n E G n E G dS

1 ˆ ˆ ˆ( ) ( ) ( ) ' ' '2 a b

inca b S S

H r H r H r j G n E n H G n H G dS

Advances in the Formulations and Accuracy of theMethod of Moments Applied to Electromagnetics

EXACT THEORY

EFIE – MFIE .. for embedded sheets

EFIE :

MFIE :

Advances in the Formulations and Accuracy of theMethod of Moments Applied to Electromagnetics

EXACT THEORY

Boundary conditions

ˆ ˆ 0i i j jn E n E

ˆ jn

ˆin

iEjE

ˆ ˆ. . 0i i i j j jn E n E

ˆ

ˆi i i

i i i

J n H

M n E

1ˆ ˆ' ' 'i i

i i i i i iS SiG n E dS G n H dS

j

2( ) ' ' ' ' ' ( )

i i

inc ii i i i s i i i i iS Si TOTAL

scattered

jZE r k G J J G dS M G dS E r

k

ˆ ˆ ˆ( ) ( ) ' . ' 'i

inci i i i i i i i i i i iS

E r E r j G n H n E G n E G dS

Advances in the Formulations and Accuracy of theMethod of Moments Applied to Electromagnetics

EXACT THEORY

Introducing the current densities

2( ) ( ) ' ' ' ' 'i i

inc ii i i i i s i i i iS Si

jZE r E r k G J J G dS M G dS

k

1ˆ ˆ'sn E n Hj

Advances in the Formulations and Accuracy of theMethod of Moments Applied to Electromagnetics

2

2

ˆ ˆ ˆ( ) ( ) ( ) ( ) ' ' ' ( ) ' '

ˆˆ ( ) ' '( ) ' ' 'ˆ ( )( ) ( )

i i

ii

inc i ii i s i i i i i s i i i i iS Si i

iinc i i ii i i i s i iii i SSi

jZ jZn r E r J r n r k G J J G dS n r M G dS

k k

jZn r M G dSn r k G J J G dSM rn r E r

k

EXACT THEORY

Normal and tangentiel component

nEFIE :

tEFIE :

Re (M) Im (M)

0 1,000 0,500

r = 4

r = 1

Re (J ) Im (J )

0 2,386 1,193

Advances in the Formulations and Accuracy of theMethod of Moments Applied to Electromagnetics

EXACT THEORY

Mie and MoM solutions D = 0/3

Flat PEC sheet

Sa

Sb

ˆ ˆan n

bJ ˆ ˆ2 inca a a b a bn H n H H J J

Advances in the Formulations and Accuracy of theMethod of Moments Applied to Electromagnetics

EXACT THEORY

(Flat) PEC sheets

Physical Optics Approximation

=> Exact solution

aJ

Advances in the Formulations and Accuracy of theMethod of Moments Applied to Electromagnetics

METHOD OF MOMENTS

e

Advances in the Formulations and Accuracy of theMethod of Moments Applied to Electromagnetics

1

( ) ( )

Ji

i i

i

NJ

i j jj

J r J f r

1

( ) ( )

Mi

i i

i

NM

i m mm

M r M f r

p+ p-

T+ T-

1

2

e

r r

RWG function

Advances in the Formulations and Accuracy of theMethod of Moments Applied to Electromagnetics

METHOD OF MOMENTS

Discretization

Exact

3rd order expansion

Linear expansion

Advances in the Formulations and Accuracy of theMethod of Moments Applied to Electromagnetics

p+ p-

1

2

T T

(Full) linear divergence conforming basis function

Transverse gradient

Advances in the Formulations and Accuracy of theMethod of Moments Applied to Electromagnetics

METHOD OF MOMENTS

On the choice of basis functions

p+ p-

T+ T-

1

2

e

r r

RWG function

Advances in the Formulations and Accuracy of theMethod of Moments Applied to Electromagnetics

Curl conforming basis functions ?

Electric current density Magnetic current density

Cube with side 0/4 and r = 2

METHOD OF MOMENTS

On the choice of basis functions

( ) ( )dS ( ) ( ) ( ) dS

J Mi i

i i i i i i

i ii i

N Ninc J M

e i e i j i i j m i mj mS S

N r E r N r Z J N D f r M K f r

( ) ( )dS ( ) ( ) ( ) dS

J Mi i

i i i i i i

i ii i

N Ninc J M

h i i h i j i i j m i mj mS S

T r Z H r T r Z J T K f r M D f r

ˆ( ) ( ) ( )i ie e iN r w r n r

ˆ( ) ( ) ( )i ih i hT r n r w r

Arbitrary normal function for the nEFIE or nMFIE

Arbitrary tangential function for the tEFIE or tMFIE

Advances in the Formulations and Accuracy of theMethod of Moments Applied to Electromagnetics

METHOD OF MOMENTS

Testing

, , ,

, , ,

, , ,

, , ,

EJ n EM n E ni i iHJ n HM n H ni i i iEJ t EM t E tii i iHJ t HM t H ti i i

Z Z V

Z Z J V

MZ Z V

Z Z V

,( , ) ( ) ( ) dS

i ii i

i

EJ n Ji e i i je jS

Z Z N r N D f r ,( ) ( ) ( )dS

ii

i

E n ince ie

S

V N r E r

,( , ) ( ) ( ) dS

i ii i

i

HM t Mh i mh m

S

Z T r D f r

,( , ) ( ) ( ) dS

i ii i

i

HJ t Ji h i i jh jS

Z Z T r T K f r

,( , ) ( ) ( ) dS

i ii i

i

EM n Me i me m

S

Z N r K f r

,( ) ( ) ( )dS

ii

i

H t inci h ihS

V Z T r H r

Advances in the Formulations and Accuracy of theMethod of Moments Applied to Electromagnetics

METHOD OF MOMENTS

Local ZI=V system of equations

tMFIE for a PEC body

--- Complex vector ---

Advances in the Formulations and Accuracy of theMethod of Moments Applied to Electromagnetics

METHOD OF MOMENTS

Current densities from I

, , ,0,(1,1) 0,(1, ) 0,(1) 0,(1)

, , ,0,( )0,( ,1) 0,( , ) 0,( )

...

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

...

HJ t HJ t H tN

HJ t HJ t H tNN N N N

Z Z VJ

JZ Z V

tMFIE for a PEC body

N=2799

r27

9

0 0,(2) 0,(2) 0,(7) 0,(7) 0,(9) 0,(9)( ) ( ) ( ) ( )J r J f r J f r J f r

Re [J /| H inc| ] Im [J /| H inc| ]

tEFIEG-f CN=14374

tMFIE-nxf CN=98

0 3,88 1,94

Side = 0/4

Advances in the Formulations and Accuracy of theMethod of Moments Applied to Electromagnetics

METHOD OF MOMENTS

PEC rounded cube

Advances in the Formulations and Accuracy of theMethod of Moments Applied to Electromagnetics

MIXED MATERIALS

Consequence :16 J + 4 M = 20 unknowns2x6+2x6+2x15 = 54 equations

OOOOOOOOOOVI

OOOOOOOOOOV

OOOOOOOOOOIV

OOOOOOOOOOIII

OOOOOOOOOOII

OOOOOOOOOO

H

I

OOOOOOOOOOVI9-10(l-r)

OOOOOOOOOOV07-08

OM4OOOOOOOOOIV05-06

OM3OOOOOOOOOIII03-04

OM2OOOOOOOOOII2

OM1OOOOOOOOO

E

I1

J13RRRRRRVII

J12RRRRRRV

J11RRRRRRIII

J10RRRRRR

H

II

J10RRRRRRVII10u

J10RRRRRRV07-08

J9RRRRRRIII03-04

J9RRRRRR

E

II2

J8LLLLLLVII

J7LLLLLLIV

J6LLLLLLIII

J5LLLLLL

H

I

J4LLLLLLVII10u

J3LLLLLLIV05-06

J2LLLLLLIII03-04

J1LLLLLL

E

I1

VJMJZm

IIIIIIVIIVIVIVIIIIIIType

03-042110u

07-08

05-06

03-0421n

OOOOOOOOOOVI

OOOOOOOOOOV

OOOOOOOOOOIV

OOOOOOOOOOIII

OOOOOOOOOOII

OOOOOOOOOO

H

I

OOOOOOOOOOVI9-10(l-r)

OOOOOOOOOOV07-08

OM4OOOOOOOOOIV05-06

OM3OOOOOOOOOIII03-04

OM2OOOOOOOOOII2

OM1OOOOOOOOO

E

I1

J13RRRRRRVII

J12RRRRRRV

J11RRRRRRIII

J10RRRRRR

H

II

J10RRRRRRVII10u

J10RRRRRRV07-08

J9RRRRRRIII03-04

J9RRRRRR

E

II2

J8LLLLLLVII

J7LLLLLLIV

J6LLLLLLIII

J5LLLLLL

H

I

J4LLLLLLVII10u

J3LLLLLLIV05-06

J2LLLLLLIII03-04

J1LLLLLL

E

I1

VJMJZm

IIIIIIVIIVIVIVIIIIIIType

03-042110u

07-08

05-06

03-0421n

Advances in the Formulations and Accuracy of theMethod of Moments Applied to Electromagnetics

N L N L N P N P N R N R N O N O

ML Z EJ Z EM J V E

ML Z HJ Z HM 0 M V H

MP Z EJ Z EM J V E

MP Z HJ Z HM * M = V H

MR Z EJ Z EM J V E

MR Z HJ Z HM M V H

MO 0 Z EJ Z EM J V E

MO Z HJ Z HM M V H

Z I = V

Boundary conditions for RWG

MIXED MATERIALS

B.C.

M4

M3

M2

M1

J13

J12

J11

J10

J10

J10

LROJ9LROROLOLROROLOLROROLOIII

ROJ9ROROOROROOROROOII

LOJ8LOOLOLOOLOLOOLO

H

I

LROJ7LRRLLRRLLRRLVII10u

OJ6OOOOOOOOOVI9-10(l-r)

ROJ5ROROOROROOROROOV07-08

LOJ4LOOLOLOOLOLOOLOIV05-06

LROJ3LROROLOLROROLOLROROLOIII03-04

ROJ2ROROOROROOROROOII2

LOJ1LOOLOLOOLOLOOLO

E

I1

VIMJZm

IIIIIIVIIVIVIVIIIIIIType

03-042110u

07-08

05-06

03-0421n

M4

M3

M2

M1

J13

J12

J11

J10

J10

J10

LROJ9LROROLOLROROLOLROROLOIII

ROJ9ROROOROROOROROOII

LOJ8LOOLOLOOLOLOOLO

H

I

LROJ7LRRLLRRLLRRLVII10u

OJ6OOOOOOOOOVI9-10(l-r)

ROJ5ROROOROROOROROOV07-08

LOJ4LOOLOLOOLOLOOLOIV05-06

LROJ3LROROLOLROROLOLROROLOIII03-04

ROJ2ROROOROROOROROOII2

LOJ1LOOLOLOOLOLOOLO

E

I1

VIMJZm

IIIIIIVIIVIVIVIIIIIIType

03-042110u

07-08

05-06

03-0421n

Obtain a square Z matrix !

Advances in the Formulations and Accuracy of theMethod of Moments Applied to Electromagnetics

Reduction

MIXED MATERIALS

Common schemes :

Non PEC edges (1,2,3,4)

PMCHWT (addition)Müller (weighted addition)

PEC edges

EFIE only (drop MFIE)MFIE only (drop EFIE)CFIE = f [EFIE,MFIE]

!! Problem with embedded sheets

PEC

r= 4

0,30

0,10

iE

iH

RMA-UCL FEKO™

PEC

r= 4

0,30

0,10

iE

iH

RMA-UCL FEKO™

Advances in the Formulations and Accuracy of theMethod of Moments Applied to Electromagnetics

MIXED MATERIALS

MoM example

Advances in the Formulations and Accuracy of theMethod of Moments Applied to Electromagnetics

MIXED MATERIALS

MoM example

0,150

r = 4

PEC

iE

iH

RMA-UCL FEKO™

Advances in the Formulations and Accuracy of theMethod of Moments Applied to Electromagnetics

E-MFIE for EMBEDDED SHEETS

1,1 1, 1,12

7,1 7, 7,12

8,1 8, 8,12

9,1 9, 9,12

10,1 10, 10,12

11,1 11, 11,12

12,1 12, 12,12

... ...

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

... ...

... ...

... ...

... ...

... ...

... ...

M M Mn

M M Mn

M M Mn

E E En

E E En

M M Mn

M M Mn

z z z

z z z

z z z

z z z

z z z

z z z

z z z

1

1 7

8

9

1012

11

12

...

...

...

M

M

M

n E

E

M

M

v

J v

vJ

v

vJ

v

v

2-edges

3-edges

64

3

21

10 115

7

8

9

12

Advances in the Formulations and Accuracy of theMethod of Moments Applied to Electromagnetics

E-MFIE for EMBEDDED SHEETS

E-MFIE

Advances in the Formulations and Accuracy of theMethod of Moments Applied to Electromagnetics

E-MFIE for EMBEDDED SHEETS

Bowtie with solderline

Gap length = 0/20

Gap length = 0 , PEC solder line

Gap length = 0 , air solder line

0 6,523,26

Im[J]/|Hinc|

Advances in the Formulations and Accuracy of theMethod of Moments Applied to Electromagnetics

ACCURACY

Hm

N

nn

HMmn

N

nn

HJmn

Em

N

nn

EMmn

N

nn

EJmn

VMZJZ

VMZJZ

11

11

..

..

.EJ EM E

HJ HM H

JZ Z V

MZ Z V

tEFIE

tMFIE

Infinite when R = 0

mT

nf

Test

Basis RWG

Sm Sn

R

2( ) ( ) ( ') ' ( ') ' ( ) 'm n

EJmn m n sS S

jZZ T r k G R f r f r G R dS dS

k

ˆ ( ) ( )( ) ( ') ' ( ) '

2m n

HJ m nmn m nS S

n r f rZ T r f r G R dS dS

Advances in the Formulations and Accuracy of theMethod of Moments Applied to Electromagnetics

ACCURACY

Numerical integration issue

Advances in the Formulations and Accuracy of theMethod of Moments Applied to Electromagnetics

ACCURACY

Polynomial quadrature

singular edge

# nodes fI = -0,03505 n fI = 0,01074

Numerical Rel error Numerical Rel error 1 -0,01693 -0,52 -0,00564 -1,53 3 -0,02545 -0,27 +0,00384 -0,63 4 -0,02613 -0,25 +0,00384 -0,64 6 -0,02969 -0,15 +0,00685 -0,36 7 -0,03102 -0,12 +0,00775 -0,28 12 -0,03217 -0,082 +0,00868 -0,19 16 -0,03517 +0,0033 +0,01074 +0,0007 19 -0,03341 -0,047 +0,00954 -0,11 25 -0,03420 -0,024 +0,01026 -0,044 42 -0,03510 +0,0012 +0,01088 +0,0136 61 -0,03450 -0,016 +0,01034 -0,037 73 -0,03481 -0,007 +0,01056 -0,017

X

Z

Y

(1,0,0)

T

T’ 'p (0,0,0)

'p p ( , ,0)r x y

(0,1,0) p

3'

1( ) ( ') '

4T T

RC T r r p dS dS

R

Advances in the Formulations and Accuracy of theMethod of Moments Applied to Electromagnetics

ACCURACY

Polynomial quadratures and regular triangles

0,0845

0,0850

0,0855

0,0860

0,0865

0,0870

0,0875

0,0880

0,0885

3 7 12 16 19 25 42 61 73

-0,586

-0,584

-0,582

-0,58

-0,578

-0,576

-0,574

Z12

Z33

2,17

2,18

2,19

2,20

2,21

2,22

2,23

3 7 12 16 19 25 42 61 73

3,056

3,057

3,058

3,059

3,060

3,061

3,062

3,063

3,064

J3 J5

1mx1mx1m (0 / 30) PEC pyramid

incE

incH

10 MHz

Advances in the Formulations and Accuracy of theMethod of Moments Applied to Electromagnetics

ACCURACY

Polynomial quadratures and regular triangles

10-8

10-6

10-4

10-2

100

102

104

106

10-4

10-2

100

102

104

1

3 4

67

12

1619

25

42

61

73

S

Rel

ativ

e er

ror

in %

424242

42

16

73

7

T = 1 = Z

I < 0 I > 0

3'

1( ) ( ') '

4T T

RC T r r p dS dS

R

Advances in the Formulations and Accuracy of theMethod of Moments Applied to Electromagnetics

ACCURACY

Polynomial quadratures and stretched triangles

Z

S T

incE

incH 300 MHz

Exact ~ 16 nodes integration 7 nodes integration

Advances in the Formulations and Accuracy of theMethod of Moments Applied to Electromagnetics

Polynomial quadratures and stretched triangles

ACCURACY

Advances in the Formulations and Accuracy of theMethod of Moments Applied to Electromagnetics

CONCLUSIONS

Advances in the Formulations and Accuracy of theMethod of Moments Applied to Electromagnetics

CONCLUSIONS

1. VECTOR FORMS OF EFIE / MFIE for VOLUMES and SHEETS Generalisation of the physical optics formula

2. CHOICE OF BASIS and TESTING Functions LIMITATIONS of RWG Curl Conforming functions

3. GENERAL CANVAS for MIXED MATERIALS

4. E-MFIE for EMBEDDED SHEETS

5. ACCURACY IMPORTANCE OF A CORRECT TREATMENT OF SINGULARITIES Reference solutions EFIE / MFIE discrepancy only close to edges (with RWG)

Advances in the Formulations and Accuracy of theMethod of Moments Applied to Electromagnetics

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