Chapter 2 Fast Algorithms for the Electromagnetic Scattering from ...
Chapter 2 Fast Algorithms for the Electromagnetic Scattering from ...
Chapter 2 Fast Algorithms for the Electromagnetic Scattering from ...
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h <br />
s s<br />
(E ,H )<br />
PEC<br />
Γ<br />
i i<br />
(E ,H )<br />
θ<br />
y<br />
c c<br />
Ω<br />
ε(x,y)<br />
Γ Γ<br />
µ<br />
0<br />
r r<br />
(E ,H )<br />
<br />
ε µ<br />
ka <br />
k a <br />
<br />
ka <br />
<br />
<br />
<br />
<br />
<br />
<br />
k 2 h <br />
<br />
h 1m × 1m <br />
h ≈ 10 −4 m 10 8 <br />
<br />
<br />
<br />
<br />
0<br />
x<br />
0
i.e. <br />
<br />
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<br />
<br />
O(M 2 ) M × M
∇ × E = iωµH,<br />
∇ × H = −iωɛE,<br />
ω ɛ µ <br />
<br />
<br />
z <br />
µ = µ0 <br />
ɛ Im(ɛ) ≥ 0<br />
<br />
z E <br />
<br />
∆u + k 2 u = f(x, y), (x, y) ∈ Ω ∪ R + 2 ,<br />
u = 0, (∂Ω\Γ) ∪ Γ c ,<br />
<br />
<br />
√ ∂us s<br />
lim r − ik0u = 0, <br />
r→∞ ∂r<br />
u s R + 2 Γ = (0, a) <br />
r = x 2 + y 2 k 2 = ω 2 ɛµ = k 2 0 ɛrµr k0 = ω √ ɛ0µ0 <br />
ɛr = ɛ/ɛ0 µr = µ/µ0 <br />
f = 0 <br />
f = 0
1<br />
∇ ·<br />
∇u<br />
ɛr<br />
<br />
+ k 2 0µru = f(x, y), (x, y) ∈ Ω ∪ R + 2<br />
, <br />
∂u<br />
= 0, (∂Ω\Γ) ∪ Γc<br />
∂n<br />
z H <br />
n <br />
<br />
i.e. <br />
<br />
u s <br />
Gd(x, x ′ ) = i<br />
<br />
4<br />
H (1)<br />
0<br />
(kr) − H(1)<br />
0 (k¯r)<br />
<br />
<br />
,<br />
∆Gd + k 2 0Gd = −δ(x, x ′ ), x, x ′ ∈ R + 2 ,<br />
Gd = 0, y = 0,<br />
<br />
√<br />
lim r<br />
r→∞<br />
∂Gd<br />
∂r<br />
<br />
− ik0Gd = 0,<br />
x = (x, y) x ′ = (x ′ , y ′ ) r = |x − x ′ | ¯r = |x − ¯x¯x¯x ′ | ¯x¯x¯x ′ = (x ′ , −y ′ ) x ′ <br />
x<br />
<br />
u s <br />
(x) =<br />
Γ<br />
∂Gd(x ′ , x)<br />
∂y ′<br />
u s (x ′ )<br />
<br />
y ′ =0 +<br />
<br />
∂Gd(x ′ , x)<br />
∂y ′<br />
<br />
<br />
<br />
y ′ =0 +<br />
= ik0y<br />
2r H(1)<br />
1 (k0r),<br />
r = (x − x ′ ) 2 + y 2 y y → 0 + <br />
∂u s (x)<br />
∂y<br />
<br />
<br />
<br />
y=0 +<br />
= ik0<br />
2<br />
<br />
Γ<br />
<br />
dx ′ ,<br />
1<br />
|x − x ′ | H(1)<br />
1 (k0|x − x ′ |)u s (x ′ , 0)<br />
<br />
∂us ∂y = IM(u s ) := ik0<br />
2<br />
<br />
=<br />
1<br />
<br />
ds(x ′ ).<br />
Γ |x − x ′ | H(1) 1 (k0|x − x ′ |)u s (x ′ , 0)dx ′ , x ∈ (0, a), <br />
<br />
= Γ
IM(u s ) = ik0<br />
2<br />
<br />
R<br />
<br />
k 2 0 − ξ2 F[ũ s ]e ξx dξ,<br />
ũs us H1/2 (R) F <br />
<br />
<br />
<br />
⎧⎨<br />
∆u + k<br />
⎩<br />
2u = 0, (x, y) ∈ Ω,<br />
u = 0, ∂Ω\Γ,<br />
∂us ∂n = IM(us ), Γ.<br />
uI = e i(αx−βy) α = k0 sin θ β =<br />
k0 cos θ −π/2 < θ < π/2 y <br />
u s <br />
u s = u − uI + e i(αx+βy) ,<br />
u u s <br />
f = 0 u <br />
⎧<br />
⎨<br />
⎩<br />
∆u + k 2 u = 0, (x, y) ∈ Ω,<br />
u = 0, ∂Ω\Γ,<br />
∂u<br />
∂n = IM(u) + gM(x), Γ,<br />
gM(x) = −2βe iαx<br />
u s <br />
Gn(x, x ′ ) = i<br />
<br />
H<br />
4<br />
(1)<br />
0 (k0r) + H (1)<br />
0 (k0¯r)<br />
<br />
<br />
∆Gn + k 2 0Gn = −δ(x, x ′ ), x, x ′ ∈ R + 2 ,<br />
∂Gn<br />
∂n<br />
<br />
= 0, y = 0,<br />
√<br />
lim r<br />
r→∞<br />
∂Gn<br />
∂r<br />
<br />
− ik0Gn = 0.<br />
<br />
u s <br />
(x) = −<br />
Γ<br />
<br />
Gn(x ′ , x) ∂us (x ′ )<br />
∂y ′<br />
<br />
y ′ =0 +<br />
dx ′ .
u s (x, 0) = IE( ∂us<br />
<br />
i<br />
) := − H<br />
∂y 2 Γ<br />
(1)<br />
0 (k0|x ′ − x|) 1<br />
ɛr<br />
∂u s (x ′ )<br />
∂y ′<br />
<br />
<br />
<br />
<br />
y ′ =0 −<br />
IE( ∂us<br />
<br />
<br />
i 1 ∂us ) = − F (y, 0) e<br />
∂n 2π R k2 0 − ξ2 ∂y iξx dξ.<br />
dx ′ . <br />
uI = ei(αx−βy) <br />
<br />
u(x, y)| y=0 + = u(x, y)| y=0 −<br />
<br />
<br />
∂u <br />
<br />
∂n<br />
y=0 +<br />
= 1<br />
ɛr<br />
<br />
∂u <br />
<br />
∂n<br />
y=0 −<br />
<br />
⎧ ⎪⎨<br />
⎪⎩<br />
<br />
1 ∇ · ɛr ∇u<br />
<br />
+ k2 0 µru = 0, (x, y) ∈ Ω,<br />
∂u<br />
∂n<br />
u = IE( ∂u<br />
∂n ) + gE, Γ,<br />
= 0, ∂Ω\Γ,<br />
,<br />
<br />
gE(x) = 2e iαx<br />
<br />
Im(k 2 ) ≥ 0 <br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
{xi, yj} M+1,N+1<br />
i,j=0 Ω = [0, a]×[−b, 0] xi+1 −xi =<br />
hx yj+1 − yj = hy uij (xi, yj)
ui−1,j − 2uij + ui+1,j<br />
h 2 x<br />
+ ui,j−1 − 2uij + ui,j+1<br />
+ k 2 (xi, yj)uij = 0,<br />
u0j = uM+1,j = ui0 = 0, i = 1, 2, . . . , M, j = 1, 2, . . . , N,<br />
h 2 y<br />
(A D x ⊗ IN + IM ⊗ A D y + D)U1 + (IM ⊗ aN+1)u:,N+1 = 0, <br />
⊗ IM M ×M <br />
<br />
<br />
A D x = 1<br />
h 2 x<br />
⎡<br />
⎢<br />
⎣<br />
−2 1<br />
1 −2 1<br />
<br />
1 −2<br />
⎤<br />
⎥<br />
⎦ , ADy = 1<br />
h2 y<br />
⎡<br />
⎢<br />
⎣<br />
−2 1<br />
1 −2 1<br />
<br />
1 −2<br />
D = (D1, D2, . . . , DM) , Di = (k 2 (xi, y1), k 2 (xi, y2), . . . , k 2 (xi, yN)),<br />
aN+1 = 1<br />
h2 eN, eN = (0, . . . , 0, 1)<br />
y<br />
T ,<br />
U1 = (u11, u12, . . . , u1N, u21, u22, . . . , u2N, . . . , uM1, . . . , uMN) T ,<br />
u:,j = (u1j, u2j, . . . , uMj) T .<br />
∂u<br />
∂y <br />
<br />
i.e.<br />
ui,N+1 − uiN<br />
hy<br />
=<br />
M<br />
l=1<br />
1<br />
u:,N + ( 1<br />
h 2 y<br />
hy<br />
g M il ul,N+1 + gM(xi), i = 1, 2, . . . , M,<br />
⎤<br />
⎥<br />
⎦ ,<br />
GM − 1<br />
h2 IM)u:,N+1 = −<br />
y<br />
1<br />
gM, <br />
hy<br />
GM = (g M ij )M i,j=1 <br />
(GM) <br />
<br />
<br />
k (ɛr(x, y)) ≥ 0 <br />
(GM)
A M 11<br />
A M 21<br />
AM 12<br />
1<br />
hy GM − 1<br />
h2 IM<br />
y<br />
U1<br />
u:,N+1<br />
<br />
=<br />
0<br />
− 1<br />
hy gM<br />
A M 11 = A D x ⊗ IN + IM ⊗ A D y + D,<br />
A M 12 = IM ⊗ aN+1, A21 = (A M 12) T .<br />
<br />
, <br />
<br />
i.e. k 2 = k 2 (y) <br />
D = IM ⊗ Dk <br />
Dk = (k 2 (y1), k 2 (y2), . . . , k 2 (yN)).<br />
<br />
<br />
A D x <br />
SMA D x SM = Λ =<br />
SM <br />
S 2 M<br />
SM =<br />
2<br />
M + 1<br />
<br />
sin lmπ<br />
M + 1<br />
M<br />
⎡<br />
⎢<br />
⎣<br />
λ1<br />
λ2<br />
, λl = −<br />
l,m=1<br />
λM<br />
⎤<br />
⎥<br />
⎦ ,<br />
4(M + 1)2<br />
a 2 sin 2 lπ<br />
2(M + 1) ,<br />
= I <br />
Λ ⊗ IN + IM ⊗ (A D y + Dk) Ū1 + (IM ⊗ aN+1)ū:,N+1 = 0, <br />
<br />
Ū1 = (SM ⊗ IN) U1 = (ū11, . . . , ū1N, ū21, . . . , ū2N, . . . , ūM1, . . . , ūMN) T ,<br />
ū:,j = SMu:,j = (ū1j, ū2j, . . . , ūMj) T .<br />
<br />
1<br />
ū:,N + SM( 1<br />
h 2 y<br />
hy<br />
GM − 1<br />
h2 IM)SMū:,N+1 = ¯gM,<br />
y<br />
¯gM = − 1<br />
hy SMgM<br />
<br />
(AD y + λiIN + Dk)ūi,: + aN+1ūi,N+1 = 0, i = 1, 2, . . . , M,<br />
1<br />
h2 ū:,N + SM(<br />
y<br />
1<br />
hy GM − 1<br />
h2 IM)SMū:,N+1 = ¯gM,<br />
y
ūi,: = (ūi1, ūi2, . . . , ūiN) T , i = 1, 2, . . . , M.<br />
<br />
<br />
A D y + λiIN + Dk = LiRi, i = 1, 2, . . . , M,<br />
A D y + λiIN + Dk Li <br />
<br />
Riūi,: + L −1<br />
i aN+1ūi,N+1 = 0, i = 1, 2, . . . , M, <br />
Ri = (ri pq)<br />
<br />
ri NN ūiN + ri N,N+1ūi,N+1 = 0, i = 1, 2, . . . , M,<br />
1<br />
h2 ū:,N + SM(<br />
y<br />
1<br />
hy GM − 1<br />
h2 IM)SMū:,N+1 = ¯gM,<br />
y<br />
<br />
r i N,N+1 L −1<br />
i aN+1 ū:,N ū:,N+1 <br />
<br />
k 2 <br />
h <br />
r i NN = 0, i = 1, 2, . . . , M.<br />
ū:,N <br />
<br />
<br />
( 1<br />
SMGMSM −<br />
hy<br />
1<br />
h2 IM −<br />
y<br />
1<br />
h2 E)ū:,N+1 = ¯gM, <br />
y<br />
( 1<br />
GM −<br />
hy<br />
1<br />
h2 IM −<br />
y<br />
1<br />
h2 SMESM)u:,N+1 = −<br />
y<br />
1<br />
gM, <br />
hy<br />
E =<br />
⎡<br />
⎢<br />
⎣<br />
r 1 N,N+1 /r1 NN<br />
<br />
r M N,N+1 /rM NN<br />
ū:,N+1 Γ <br />
<br />
<br />
(A D y + λiIN + Dk)ūi,: = −aN+1ūi,N+1, i = 1, 2, . . . , M, <br />
1<br />
ū:,N + SM( 1<br />
h 2 y<br />
<br />
<br />
<br />
hy<br />
⎤<br />
⎥<br />
⎦ .<br />
GM − 1<br />
h2 IM)SMū:,N+1 = ¯gM<br />
y
GM<br />
Ri E <br />
<br />
¯gM<br />
ū:,N+1 u:,N+1<br />
<br />
<br />
<br />
A = 1<br />
hy<br />
SMGMSM − 1<br />
h2 IM −<br />
y<br />
1<br />
h2 E.<br />
y<br />
<br />
<br />
<br />
P = − 1<br />
h2 (IM + E)<br />
y<br />
<br />
AP −1 v = ¯gM P ū:,N+1 = v. <br />
<br />
¯gM − AP −1 v p 2<br />
¯gM − AP −1 v 0 2<br />
v p p v 0 <br />
GM <br />
IM(u) GM<br />
<br />
<br />
12M log M A P <br />
<br />
12M log M<br />
<br />
u:,N+1 <br />
<br />
<br />
p <br />
p <br />
<br />
≤ δ,
u f = 0<br />
O(M)<br />
3MN<br />
2M log M<br />
O(12pM log M)<br />
5MN<br />
O(MN) + 12pM log M<br />
<br />
<br />
1<br />
<br />
1<br />
hx ɛr(xi+1/2, yj)<br />
+ 1<br />
<br />
1<br />
hy ɛr(xi, yj+1/2) ui+1,j − uij<br />
hx<br />
ui,j+1 − uij<br />
hy<br />
−<br />
1<br />
ɛr(x i−1/2, yj)<br />
−<br />
1<br />
ɛr(xi, y j−1/2)<br />
uij − ui−1,j<br />
hx<br />
<br />
uij − ui,j−1<br />
+k 2 0(xi, yj)µruij = 0, i = 1, 2, . . . , M, j = 1, 2, . . . , N,<br />
<br />
u1j − u0j<br />
hx<br />
uMj − uM+1,j<br />
hx<br />
ui1 − ui0<br />
hy<br />
= 0, j = 1, 2, . . . , N,<br />
= 0, j = 1, 2, . . . , N,<br />
= 0, i = 1, 2, . . . , M.<br />
<br />
i.e.<br />
<br />
ui,N+1 = 1<br />
hy<br />
M<br />
l=1<br />
1<br />
ɛr(xl, y 1<br />
N+ )<br />
2<br />
gE il (ul,N+1 − ulN) + gE(xi), i = 1, 2, . . . , M,<br />
1<br />
GEDɛru:,N + (IM − 1<br />
GEDɛr)u:,N+1 = gE,<br />
hy<br />
Dɛr = (1/ɛr(x1, y N+ 1<br />
2<br />
hy<br />
), 1/ɛr(x2, y N+ 1<br />
2<br />
hy<br />
<br />
), . . . , 1/ɛr(xM, y 1<br />
N+ )),<br />
2<br />
GE = [g E ij ]M i,j=1 <br />
GE <br />
ɛr = ɛr(y) <br />
<br />
A E 11<br />
A E 21<br />
1<br />
hy G−1<br />
E<br />
A E 12<br />
1 − h2 Dɛr<br />
y<br />
U1<br />
u:,N+1<br />
<br />
=<br />
0<br />
1<br />
hy G−1<br />
E gE<br />
<br />
,
A ND<br />
y<br />
= 1<br />
h 2 y<br />
A N x = 1<br />
h 2 x<br />
⎡<br />
⎢<br />
⎣<br />
⎡<br />
⎢<br />
⎣<br />
− 1<br />
ɛr(y<br />
1+ 1 )<br />
2<br />
,<br />
1<br />
ɛr(y 2− 1 2<br />
A E 11 = A N x ⊗ ˜ Dɛr + IM ⊗ A ND<br />
y + k 2 0µrI,<br />
A E 1<br />
12 =<br />
h2 yɛr(yN+1/2) IM ⊗ eN, A E 21 = (A E 12) T ,<br />
) , −<br />
<br />
−1 1<br />
1 −2 1<br />
<br />
1 −1<br />
1<br />
ɛr(y<br />
1+ 1 )<br />
2<br />
1<br />
ɛr(y<br />
2− 1 )<br />
2<br />
+ 1<br />
ɛr(y<br />
2+ 1 )<br />
2<br />
⎤<br />
<br />
,<br />
1<br />
ɛr(y<br />
2+ 1 )<br />
2<br />
<br />
1<br />
ɛr(y N− 1 2<br />
) , −( 1<br />
ɛr(y<br />
N− 1 )<br />
2<br />
+<br />
1<br />
ɛr(y<br />
N+ 1 )<br />
2<br />
)<br />
⎥<br />
⎦ Dɛr<br />
˜ = (1/ɛr(y1), 1/ɛr(y2), . . . , 1/ɛr(yN)).<br />
<br />
k Im(ɛr(x, y)) ≥ 0 <br />
Im(GE) <br />
<br />
<br />
<br />
<br />
<br />
<br />
u ∈ H 1 M(Ω) := {u ∈ H 1 (Ω) ∩ H 1/2<br />
00 (Γ), u = 0 ∂Ω\Γ}<br />
a(u, v) = −(gM, v)Γ,<br />
<br />
<br />
a(u, v) = − ∇u · ∇vdxdy +<br />
Ω<br />
<br />
(gM, v)Γ =<br />
Γ<br />
Ω<br />
k 2 <br />
u¯vdxdy + IM(u)¯v(x, 0)dx,<br />
Γ<br />
gM(x)¯v(x, 0)dx,<br />
H 1/2<br />
00 (Γ) = {u ∈ H1/2 (Γ) : ũ ∈ H 1/2 (R) ũ = 0 R\Γ u = ũ}.<br />
{xi, yj} <br />
Th Ω <br />
⎤<br />
⎥ ,<br />
⎥<br />
⎦
K ⊂ Ω Ks Γ V M h ∈ H1 M (Ω)<br />
<br />
vh ∈ V M h <br />
V M h = {vh ∈ H 1 M(Ω) : vh|K ∈ (P1 × P1)(K) K ∈ Th}.<br />
vh(x, y) =<br />
ξi(x) <br />
<br />
<br />
AM BM<br />
<br />
<br />
B T M<br />
TM<br />
M<br />
i=1<br />
N+1 <br />
j=1<br />
u<br />
ub<br />
vijξi(x)ξj(y),<br />
<br />
0<br />
=<br />
a M <br />
′<br />
mn = − ξ i1<br />
Ω<br />
(x)ξj1 (y)ξ′ i2 (x)ξj2 (y) + ξi1 (x)ξ′ j1 (y)ξi2 (x)ξ′ j2 (y) dxdy<br />
<br />
+ k<br />
Ω<br />
2 ξi1 (x)ξj1 (y)ξi2 (x)ξj2 (y)dxdy, i1, i2 = 1, 2, . . . , M; j1, j2 = 1, 2, . . . , N,<br />
b M <br />
′<br />
m,i2 = − ξ i1<br />
Ω<br />
(x)ξj1 (y)ξ′ i2 (x)ξN+1(y) + ξi1 (x)ξ′ j1 (y)ξi2 (x)ξ′ N+1(y) dxdy<br />
<br />
+ k<br />
Ω<br />
2 ξi1 (x)ξj1 (y)ξi2 (x)ξN+1(y)dxdy, i1, i2 = 1, 2, . . . , M; j1 = 1, 2, . . . , N,<br />
t M <br />
′<br />
i1,i2 = − ξ i1<br />
Ω<br />
(x)ξN+1(y)ξ ′ i2 (x)ξN+1(y) + ξi1 (x)ξ′ N+1(y)ξi2 (x)ξ′ N+1(y) dxdy<br />
<br />
+ k<br />
Ω<br />
2 ξi1 (x)ξN+1(y)ξi2 (x)ξN+1(y)dxdy<br />
<br />
+ IM(ξi2<br />
Γ<br />
)ξi1 (x)dx, i1, i2 = 1, 2, . . . , M,<br />
f M <br />
i1 = − gMξi1<br />
Γ<br />
(x)dx, i1 = 1, 2, . . . , M,<br />
m = (i1 − 1)N + j1, n = (i2 − 1)N + j2.<br />
<br />
<br />
A1 = hxA D x A2 = hyA D y <br />
C1 = hx<br />
⎡<br />
⎢<br />
⎣<br />
fM<br />
<br />
,<br />
AM = A1 ⊗ C2 + C1 ⊗ A2 + C1 ⊗ C2M,<br />
BM = hy<br />
6 A1 ⊗ eN + 1<br />
C1 ⊗ eN + cN+1C1 ⊗ eN,<br />
2/3 1/6<br />
1/6 2/3 1/6<br />
<br />
1/6 2/3<br />
⎤<br />
hy<br />
⎡<br />
⎥<br />
⎦ , C2<br />
⎢<br />
= hy ⎢<br />
⎣<br />
2/3 1/6<br />
1/6 2/3 1/6<br />
<br />
1/6 2/3<br />
⎤<br />
⎥<br />
⎦ ,
C2M <br />
0<br />
(C2M)ij =<br />
−b<br />
k 2 (y)ξi(y)ξj(y)dy, cN+1 =<br />
0<br />
−b<br />
k 2 (y)ξN(y)ξN+1(y)dy.<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
ψ = ∂u <br />
<br />
∂y<br />
ψ = ɛ −1<br />
r<br />
H 1 e (Ω) = {u ∈ H 1 (Ω), ∂u<br />
∂n<br />
y=0 +<br />
<br />
∂u <br />
<br />
∂y<br />
.<br />
y=0 −<br />
∈ H−1/2<br />
00<br />
.<br />
(Γ), u = IE( ∂u<br />
) Γ},<br />
∂n<br />
Heb(Γ) = {φ ∈ H −1/2 (Γ) : v ∈ H 1 e (Ω) ∂v<br />
∂y<br />
= φ Γ}.<br />
u ∈ H 1 e (Ω) ψ ∈ Heb(Γ) <br />
−(ɛ −1<br />
r ∇u, ∇v) + (k 2 0µru, v) + (ψ, v)Γ = 0, v ∈ H 1 e (Ω),<br />
(u, φ)Γ − (IE(ψ), φ)Γ = (gE, φ)Γ, φ ∈ Heb(Γ).<br />
<br />
u ψ <br />
V E h ∈ H1 e (Ω) W E h ∈ Heb(Γ) <br />
<br />
vh ∈ V E h φh ∈ W E h <br />
V E h = {vh ∈ H 1 e (Ω) : vh|K ∈ (P1 × P1)(K) K ∈ Th},<br />
W E h = {φh ∈ Heb(Γ) : φh|Ks ∈ P1(Ks) Ks ∈ Γ}.<br />
vh(x, y) =<br />
φh(x) =<br />
M+1 <br />
i=0<br />
M+1 <br />
i=0<br />
N+1 <br />
j=0<br />
vijξi(x)ξj(y), (x, y) ∈ Ω,<br />
φiξi(x), x ∈ Γ,<br />
ξi(x) Γ <br />
<br />
vh(x, 0) =<br />
M+1 <br />
vi,N+1ξi(x).<br />
i=0
a E <br />
mn = −<br />
<br />
+<br />
Ω <br />
b E m,i2 =<br />
Ω<br />
AE BE<br />
B T E TE<br />
u<br />
ψ<br />
<br />
0<br />
=<br />
ɛ −1 ′<br />
r ξ i1 (x)ξj1 (y)ξ′ i2 (x)ξj2 (y) + ξi1 (x)ξ′ j1 (y)ξi2 (x)ξ′ j2 (y) dxdy<br />
fE<br />
<br />
, <br />
k 2 0µrξi1 (x)ξj1 (y)ξi2 (x)ξj2 (y)dxdy, i1, i2 = 0, 1, . . . , M + 1; j1, j2 = 0, 1, . . . , N + 1,<br />
<br />
ξi1<br />
Γ<br />
(x)ξi2 (x)dx, i1, i2 = 0, 1, . . . , M + 1,<br />
t E i1,i2 = IE(ξi2<br />
Γ<br />
(x′ ))ξi1 (x)dx, i1, i2 = 0, 1, . . . , M + 1,<br />
f E i1 =<br />
<br />
gE(x)ξi1<br />
Γ<br />
(x)dx, i1 = 0, 1, . . . , M + 1,<br />
m = i1(N + 2) + j1, n = i2(N + 2) + j2.<br />
ɛr = ɛr(y) <br />
A N 1 = hxA N x <br />
C N 1 = hx<br />
⎡<br />
⎢<br />
⎣<br />
AE = A N 1 ⊗ ˜ C2E + C N 1 ⊗ A ND<br />
2E + k 2 0µrC N 1 ⊗ C N 2 ,<br />
BE = C1 ⊗ eN+2,<br />
1/3 1/6<br />
1/6 2/3 1/6<br />
<br />
1/6 2/3 1/6<br />
1/6 1/3<br />
A ND<br />
2E ˜ C2E <br />
(A ND<br />
0<br />
2E )ij = −<br />
−b<br />
⎤<br />
⎥<br />
⎦<br />
, C N 2 = hy<br />
⎡<br />
⎢<br />
⎣<br />
ɛ −1<br />
r (y)ξ ′ i(y)ξ ′ j(y)dy, ( ˜ C2E)ij =<br />
1/3 1/6<br />
1/6 2/3 1/6<br />
<br />
1/6 2/3 1/6<br />
1/6 1/3<br />
0<br />
−b<br />
ɛ −1<br />
r (y)ξi(y)ξj(y)dy.<br />
<br />
<br />
GM<br />
GE TM TE <br />
Jν(z) Yν(z) H (1)<br />
1<br />
H (1)<br />
1 (z) = J1(z) + iY1(z).<br />
(z) <br />
⎤<br />
⎥ ,<br />
⎥<br />
⎦
J1(z) ∼ O(z), Y1(z) ∼ O( 1<br />
),<br />
z<br />
z → 0,<br />
IM(u) <br />
J1(z) = J1(z)/z <br />
<br />
<br />
(IM(u)(xi, 0)) = k0<br />
2<br />
a<br />
0<br />
1<br />
|xi − x ′ | J1(k0|xi − x ′ |)u(x ′ , 0)dx ′ ≈ (g M ij )u(xj, 0),<br />
(g M ij ) = k2 0 hx<br />
2 J1(k0|xi − xj|),<br />
<br />
<br />
e.g. <br />
<br />
a<br />
(IM(u)) = −1<br />
=<br />
2 0<br />
Y1(k0|x − x ′ |)u(x ′ , 0)<br />
(x − x ′ ) 2 dx ′ ≈ (g M ij )u(xj, 0),<br />
Y1(z) = zY1(z) (gM ij ) = −αij Y1(k0|xi − xj|)/2 <br />
αij =<br />
⎧<br />
⎪⎨<br />
⎪⎩<br />
1 (1 − ln 2), |i − j| = 1,<br />
hx<br />
− 2 , i = j,<br />
hx<br />
1 (j−i)2<br />
h ln x (j−i) 2 , .<br />
−1<br />
O(hx)<br />
<br />
<br />
<br />
<br />
IE(v)(x) = I (1)<br />
E (v)(x) + I(2)<br />
E (v)(x),<br />
I (1)<br />
<br />
1<br />
E (v)(x) =<br />
2 Γ<br />
I (2)<br />
<br />
i<br />
E (v)(x) = −<br />
2 Γ<br />
J0(z) I (1)<br />
E<br />
I (1)<br />
E<br />
I (1)<br />
E (v)(xi) = 1<br />
2<br />
(v)(x) <br />
<br />
Γ<br />
1<br />
ɛr(x ′ ) Y0(k0|x − x ′ |)v(x ′ )dx ′ ,<br />
1<br />
ɛr(x ′ ) J0(k0|x − x ′ |)v(x ′ )dx ′ . <br />
Y0(z) ∼ ( 2 z<br />
ln<br />
π 2 )J0(z), z → 0,<br />
1<br />
ɛr(x ′ ) Y0(k0|xi − x ′ |)v(x ′ )dx ′ + 1<br />
2<br />
(v)(x) I(2)<br />
E (v)(x) <br />
<br />
Γ<br />
1<br />
ɛr(x ′ )<br />
2<br />
π ln k0|xi − x ′ |<br />
2<br />
<br />
J0(0)v(x ′ )dx ′ ,
Y0(z) = Y0(z) − ( 2<br />
π<br />
<br />
1<br />
2<br />
<br />
Γ<br />
ln z<br />
2 )J0(0) <br />
1<br />
ɛr(x ′ ) Y0(k0|xi − x ′ |)v(x ′ )dx ′ ≈ <br />
i.e.<br />
<br />
1<br />
2 Γ<br />
1<br />
ɛr(x ′ )<br />
<br />
2<br />
π ln k0|xi − x ′ |<br />
2<br />
<br />
<br />
<br />
<br />
J0(0)v(x ′ )dx ′ ≈ J0(0) <br />
π<br />
j<br />
I (1)<br />
E (v)(xi) ≈ <br />
j<br />
j<br />
hx<br />
2 Y0(k0|xi − xj|) v(xj)<br />
ɛr(xj) .<br />
<br />
v(xj)<br />
ɛr(xj) Γ<br />
(g E ij) v(xj)<br />
ɛr(xj) ,<br />
(g E ij) = hx<br />
2 Y0(k0|xi − xj|) + J0(0)<br />
xj+1<br />
π xj−1<br />
ln k0|(xi − x ′ )|<br />
ξj(x<br />
2<br />
′ )dx ′<br />
<br />
,<br />
ln k0|xi − x ′ |<br />
ξj(x<br />
2<br />
′ )dx ′ .<br />
I (2)<br />
E (v)(x) <br />
I (2)<br />
E (v)(xi) = − 1<br />
<br />
2 Γ<br />
1<br />
ɛr(x ′ ) J0(k0|xi − x ′ |)v(x ′ )dx ′ ≈ <br />
j<br />
(g E ij) v(xj)<br />
ɛr(xj)<br />
(g E ij) = − hx<br />
2 J0(k0|xi − xj|).<br />
<br />
<br />
(g M ij )<br />
(g E ij )<br />
<br />
(gM ij )<br />
<br />
GM = Gre M + iGim M GE = Gre E + iGim E Gre M = Gim M =<br />
<br />
(gM ij )<br />
<br />
Gre E =<br />
<br />
(gE ij )<br />
<br />
Gim E =<br />
<br />
(gE ij )<br />
<br />
k Im(ɛr(x, y)) ≥ 0<br />
GE Gim M Gim E <br />
<br />
G im M <br />
G im M G im E <br />
TM TE <br />
<br />
H (1)<br />
1 (z)<br />
z<br />
= H (1) d<br />
0 (z) −<br />
dz H(1) 1<br />
(z) = H(1)<br />
0<br />
d2<br />
(z) + H(1)<br />
dz2 0 (z),
t M ij = ik0<br />
2<br />
= ik2 0<br />
2<br />
− i<br />
2<br />
<br />
<br />
H (1)<br />
1 (k0|x − x ′ |)<br />
|x − x ′ |<br />
Γ Γ<br />
xi+1 xj+1<br />
xi−1 xj−1<br />
xi+1 xj+1<br />
xi−1<br />
xj−1<br />
ξi(x)ξj(x ′ )dxdx ′<br />
H (1)<br />
0 (k0(x − x ′ ))ξi(x)ξj(x ′ )dxdx ′<br />
H (1)<br />
0 (k0(x − x ′ ))ξ ′ i(x)ξ ′ j(x ′ )dxdx ′ .<br />
H (1)<br />
0 (z) <br />
<br />
t E ij = − i<br />
xi+1 xj+1<br />
H<br />
2 xi−1 xj−1<br />
(1)<br />
0 (k0|x − x ′ |)ξi(x)ξj(x ′ )dxdx ′ ,<br />
<br />
<br />
<br />
<br />
<br />
<br />
δ = hx/5<br />
1 <br />
0.25 a = 1.0 b = 0.25 <br />
ɛr = 1.0 ɛr = 4 + i <br />
<br />
⎧<br />
⎨ ɛr0 , −b/3 ≤ y < 0,<br />
ɛr(x, y) = 1.5ɛr0 , −2b/3 ≤ y < −b/3,<br />
⎩<br />
2ɛr0 , −b ≤ y < −2b/3.<br />
<br />
k0 = 2π <br />
<br />
σ = 4<br />
|P (φ)| 2 ,<br />
φ P <br />
P (φ) = k0<br />
2<br />
k0<br />
<br />
sin φ<br />
Γ<br />
u(x, 0)e ik0x cos φ dx.<br />
<br />
k0 = 2π <br />
θ = 0
PHASE<br />
RCS σ/λ (dB)<br />
MAGNITUDE<br />
3<br />
2<br />
1<br />
−100<br />
(a)<br />
0<br />
0 0.2 0.4 0.6 0.8 1<br />
x<br />
(b)<br />
50<br />
0<br />
−50<br />
0 0.2 0.4 0.6 0.8 1<br />
x<br />
(c)<br />
20<br />
0<br />
−20<br />
−40<br />
−60<br />
−80<br />
100 120 140<br />
φ (degree)<br />
160 180<br />
PHASE<br />
RCS σ/λ (dB)<br />
MAGNITUDE<br />
3<br />
2<br />
1<br />
−100<br />
<br />
(d)<br />
0<br />
0 0.2 0.4 0.6 0.8 1<br />
x<br />
(e)<br />
50<br />
0<br />
−50<br />
0 0.2 0.4 0.6 0.8 1<br />
x<br />
(f)<br />
20<br />
0<br />
−20<br />
−40<br />
−60<br />
−80<br />
100 120 140<br />
φ (degree)<br />
160 180<br />
<br />
k0 = 2π ɛr = 1.0<br />
ɛr = 4 + i <br />
<br />
k0 = 16π ɛr = 4+i <br />
Γ M = N = 1024<br />
θ = 0<br />
<br />
k0 <br />
<br />
N = M = 2048 M <br />
x MN <br />
<br />
<br />
u:,N+1 O(M 2 ) M × M
MAGNITUDE<br />
2<br />
1.5<br />
1<br />
0.5<br />
(a): k 0 =16π,ε r =4+i,θ=0<br />
0<br />
0 0.2 0.4 0.6 0.8 1<br />
x<br />
2<br />
1.5<br />
1<br />
0.5<br />
<br />
(b): k 0 =16π,inhomogeneous medium,θ=0<br />
0<br />
0 0.2 0.4 0.6 0.8 1<br />
k0 = 16π <br />
ɛr ɛr = 4 + i <br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
MAGNITUDE<br />
x
δ = hx/5<br />
k0 <br />
M × N <br />
k0 = 4π 256 2 <br />
512 2 <br />
1024 2 <br />
2048 2 <br />
k0 = 8π 256 2 <br />
512 2 <br />
1024 2 <br />
2048 2 <br />
k0 = 16π 256 2 <br />
512 2 <br />
1024 2 <br />
2048 2 <br />
k0 = 32π 256 2 <br />
512 2 <br />
1024 2 <br />
2048 2 <br />
k0 = 4π 256 2 <br />
ɛr = 4 + 512 2 <br />
1024 2 <br />
2048 2 <br />
k0 = 8π 256 2 <br />
512 2 <br />
1024 2 <br />
2048 2
δ = hx/5<br />
k0 <br />
M × N <br />
k0 = 4π 256 2 <br />
512 2 <br />
1024 2 <br />
2048 2 <br />
k0 = 8π 256 2 <br />
512 2 <br />
1024 2 <br />
2048 2 <br />
k0 = 16π 256 2 <br />
512 2 <br />
1024 2 <br />
2048 2 <br />
k0 = 32π 256 2 <br />
512 2 <br />
1024 2 <br />
2048 2 <br />
k0 = 4π 256 2 <br />
ɛr = 4 + 512 2 <br />
1024 2 <br />
2048 2 <br />
k0 = 8π 256 2 <br />
512 2 <br />
1024 2 <br />
2048 2
δ = hx/5<br />
k0 <br />
M × N <br />
k0 = 4π 256 2 <br />
512 2 <br />
1024 2 <br />
2048 2 <br />
k0 = 8π 256 2 <br />
512 2 <br />
1024 2 <br />
2048 2 <br />
k0 = 16π 256 2 <br />
512 2 <br />
1024 2 <br />
2048 2 <br />
k0 = 32π 256 2 <br />
512 2 <br />
1024 2 <br />
2048 2 <br />
k0 = 4π 256 2 <br />
ɛr = 4 + 512 2 <br />
1024 2 <br />
2048 2 <br />
k0 = 8π 256 2 <br />
512 2 <br />
1024 2 <br />
2048 2