Appendix D
Coordinate systems
Rectangular coordinate system
Coordinate variables
u = x, ?∞ < x < ∞ (D.1)
v = y, ?∞ < y < ∞ (D.2)
w = z, ?∞ < z < ∞ (D.3)
Vector algebra
A = ?xA
x
+ ?yA
y
+ ?zA
z
(D.4)
A · B = A
x
B
x
+ A
y
B
y
+ A
z
B
z
(D.5)
A × B =
vextendsingle
vextendsingle
vextendsingle
vextendsingle
vextendsingle
vextendsingle
?x ?y ?z
A
x
A
y
A
z
B
x
B
y
B
z
vextendsingle
vextendsingle
vextendsingle
vextendsingle
vextendsingle
vextendsingle
(D.6)
Dyadic representation
ˉa = ?xa
xx
?x + ?xa
xy
?y + ?xa
xz
?z +
+ ?ya
yx
?x + ?ya
yy
?y + ?ya
yz
?z +
+ ?za
zx
?x + ?za
zy
?y + ?za
zz
?z (D.7)
ˉa = ?xa
prime
x
+ ?ya
prime
y
+ ?za
prime
z
= a
x
?x + a
y
?y + a
z
?z (D.8)
a
prime
x
= a
xx
?x + a
xy
?y + a
xz
?z (D.9)
a
prime
y
= a
yx
?x + a
yy
?y + a
yz
?z (D.10)
a
prime
z
= a
zx
?x + a
zy
?y + a
zz
?z (D.11)
a
x
= a
xx
?x + a
yx
?y + a
zx
?z (D.12)
a
y
= a
xy
?x + a
yy
?y + a
zy
?z (D.13)
a
z
= a
xz
?x + a
yz
?y + a
zz
?z (D.14)
Di?erential operations
dl = ?x dx + ?y dy+ ?z dz (D.15)
dV = dx dydz (D.16)
dS
x
= dydz (D.17)
dS
y
= dx dz (D.18)
dS
z
= dx dy (D.19)
? f = ?x
?f
?x
+ ?y
?f
?y
+ ?z
?f
?z
(D.20)
?·F =
?F
x
?x
+
?F
y
?y
+
?F
z
?z
(D.21)
?×F =
vextendsingle
vextendsingle
vextendsingle
vextendsingle
vextendsingle
vextendsingle
?x ?y ?z
?
?x
?
?y
?
?z
F
x
F
y
F
z
vextendsingle
vextendsingle
vextendsingle
vextendsingle
vextendsingle
vextendsingle
(D.22)
?
2
f =
?
2
f
?x
2
+
?
2
f
?y
2
+
?
2
f
?z
2
(D.23)
?
2
F = ?x?
2
F
x
+ ?y?
2
F
y
+ ?z?
2
F
z
(D.24)
Separation of the Helmholtz equation
?
2
ψ(x, y, z)
?x
2
+
?
2
ψ(x, y, z)
?y
2
+
?
2
ψ(x, y, z)
?z
2
+ k
2
ψ(x, y, z) = 0 (D.25)
ψ(x, y, z) = X(x)Y(y)Z(z) (D.26)
k
2
x
+ k
2
y
+ k
2
z
= k
2
(D.27)
d
2
X(x)
dx
2
+ k
2
x
X(x) = 0 (D.28)
d
2
Y(y)
dy
2
+ k
2
y
Y(y) = 0 (D.29)
d
2
Z(z)
dz
2
+ k
2
z
Z(z) = 0 (D.30)
X(x) =
braceleftBigg
A
x
F
1
(k
x
x)+ B
x
F
2
(k
x
x), k
x
negationslash= 0,
a
x
x + b
x
, k
x
= 0.
(D.31)
Y(y) =
braceleftBigg
A
y
F
1
(k
y
y)+ B
y
F
2
(k
y
y), k
y
negationslash= 0,
a
y
y + b
y
, k
y
= 0.
(D.32)
Z(z) =
braceleftBigg
A
z
F
1
(k
z
z)+ B
z
F
2
(k
z
z), k
z
negationslash= 0,
a
z
z + b
z
, k
z
= 0.
(D.33)
F
1
(ξ), F
2
(ξ) =
?
?
?
?
?
?
?
?
?
e
jξ
e
?jξ
sin(ξ)
cos(ξ)
(D.34)
Cylindrical coordinate system
Coordinate variables
u = ρ, 0 ≤ ρ<∞ (D.35)
v = φ, ?π ≤ φ ≤ π (D.36)
w = z, ?∞ < z < ∞ (D.37)
x = ρ cosφ (D.38)
y = ρ sinφ (D.39)
z = z (D.40)
ρ =
radicalbig
x
2
+ y
2
(D.41)
φ = tan
?1
y
x
(D.42)
z = z (D.43)
Vector algebra
?ρ = ?x cosφ + ?y sinφ (D.44)
?
φ =??x sinφ + ?y cosφ (D.45)
?z = ?z (D.46)
A = ?ρA
ρ
+
?
φA
φ
+ ?zA
z
(D.47)
A · B = A
ρ
B
ρ
+ A
φ
B
φ
+ A
z
B
z
(D.48)
A × B =
vextendsingle
vextendsingle
vextendsingle
vextendsingle
vextendsingle
vextendsingle
?ρ
?
φ ?z
A
ρ
A
φ
A
z
B
ρ
B
φ
B
z
vextendsingle
vextendsingle
vextendsingle
vextendsingle
vextendsingle
vextendsingle
(D.49)
Dyadic representation
ˉa = ?ρa
ρρ
?ρ+ ?ρa
ρφ
?
φ+ ?ρa
ρz
?z +
+
?
φa
φρ
?ρ+
?
φa
φφ
?
φ+
?
φa
φz
?z +
+ ?za
zρ
?ρ+ ?za
zφ
?
φ+ ?za
zz
?z (D.50)
ˉa = ?ρa
prime
ρ
+
?
φa
prime
φ
+ ?za
prime
z
= a
ρ
?ρ+ a
φ
?
φ+ a
z
?z (D.51)
a
prime
ρ
= a
ρρ
?ρ+ a
ρφ
?
φ+ a
ρz
?z (D.52)
a
prime
φ
= a
φρ
?ρ+ a
φφ
?
φ+ a
φz
?z (D.53)
a
prime
z
= a
zρ
?ρ+ a
zφ
?
φ+ a
zz
?z (D.54)
a
ρ
= a
ρρ
?ρ+ a
φρ
?
φ+ a
zρ
?z (D.55)
a
φ
= a
ρφ
?ρ+ a
φφ
?
φ+ a
zφ
?z (D.56)
a
z
= a
ρz
?ρ+ a
φz
?
φ+ a
zz
?z (D.57)
Di?erential operations
dl = ?ρdρ +
?
φρ dφ + ?z dz (D.58)
dV = ρ dρ dφ dz (D.59)
dS
ρ
= ρ dφ dz, (D.60)
dS
φ
= dρ dz, (D.61)
dS
z
= ρ dρ dφ (D.62)
? f = ?ρ
?f
?ρ
+
?
φ
1
ρ
?f
?φ
+ ?z
?f
?z
(D.63)
?·F =
1
ρ
?
?ρ
parenleftbig
ρF
ρ
parenrightbig
+
1
ρ
?F
φ
?φ
+
?F
z
?z
(D.64)
?×F =
1
ρ
vextendsingle
vextendsingle
vextendsingle
vextendsingle
vextendsingle
vextendsingle
?ρ ρ
?
φ ?z
?
?ρ
?
?φ
?
?z
F
ρ
ρF
φ
F
z
vextendsingle
vextendsingle
vextendsingle
vextendsingle
vextendsingle
vextendsingle
(D.65)
?
2
f =
1
ρ
?
?ρ
parenleftbigg
ρ
?f
?ρ
parenrightbigg
+
1
ρ
2
?
2
f
?φ
2
+
?
2
f
?z
2
(D.66)
?
2
F = ?ρ
parenleftbigg
?
2
F
ρ
?
2
ρ
2
?F
φ
?φ
?
F
ρ
ρ
2
parenrightbigg
+
?
φ
parenleftbigg
?
2
F
φ
+
2
ρ
2
?F
ρ
?φ
?
F
φ
ρ
2
parenrightbigg
+ ?z?
2
F
z
(D.67)
Separation of the Helmholtz equation
1
ρ
?
?ρ
parenleftbigg
ρ
?ψ(ρ,φ, z)
?ρ
parenrightbigg
+
1
ρ
2
?
2
ψ(ρ,φ,z)
?φ
2
+
?
2
ψ(ρ,φ,z)
?z
2
+ k
2
ψ(ρ,φ,z) = 0 (D.68)
ψ(ρ,φ,z) = P(ρ)Phi1(φ)Z(z) (D.69)
k
2
c
= k
2
? k
2
z
(D.70)
d
2
P(ρ)
dρ
2
+
1
ρ
dP(ρ)
dρ
+
parenleftBigg
k
2
c
?
k
2
φ
ρ
2
parenrightBigg
P(ρ) = 0 (D.71)
?
2
Phi1(φ)
?φ
2
+ k
2
φ
Phi1(φ) = 0 (D.72)
d
2
Z(z)
dz
2
+ k
2
z
Z(z) = 0 (D.73)
Z(z) =
braceleftBigg
A
z
F
1
(k
z
z)+ B
z
F
2
(k
z
z), k
z
negationslash= 0,
a
z
z + b
z
, k
z
= 0.
(D.74)
Phi1(φ) =
braceleftBigg
A
φ
F
1
(k
φ
φ)+ B
φ
F
2
(k
φ
φ), k
φ
negationslash= 0,
a
φ
φ + b
φ
, k
φ
= 0.
(D.75)
P(ρ) =
?
?
?
?
?
a
ρ
lnρ + b
ρ
, k
c
= k
φ
= 0,
a
ρ
ρ
?k
φ
+ b
ρ
ρ
k
φ
, k
c
= 0 and k
φ
negationslash= 0,
A
ρ
G
1
(k
c
ρ)+ B
ρ
G
2
(k
c
ρ), otherwise.
(D.76)
F
1
(ξ), F
2
(ξ) =
?
?
?
?
?
?
?
?
?
e
jξ
e
?jξ
sin(ξ)
cos(ξ)
(D.77)
G
1
(ξ), G
2
(ξ) =
?
?
?
?
?
?
?
?
?
J
k
φ
(ξ)
N
k
φ
(ξ)
H
(1)
k
φ
(ξ)
H
(2)
k
φ
(ξ)
(D.78)
Spherical coordinate system
Coordinate variables
u = r, 0 ≤ r < ∞ (D.79)
v = θ, 0 ≤ θ ≤ π (D.80)
w = φ, ?π ≤ φ ≤ π (D.81)
x = r sinθ cosφ (D.82)
y = r sinθ sinφ (D.83)
z = r cosθ (D.84)
r =
radicalbig
x
2
+ y
2
+ z
2
(D.85)
θ = tan
?1
radicalbig
x
2
+ y
2
z
(D.86)
φ = tan
?1
y
x
(D.87)
Vector algebra
?r = ?x sinθ cosφ + ?y sinθ sinφ + ?z cosθ (D.88)
?
θ = ?x cosθ cosφ + ?y cosθ sinφ ? ?z sinθ (D.89)
?
φ =??x sinφ + ?y cosφ (D.90)
A = ?rA
r
+
?
θA
θ
+
?
φA
φ
(D.91)
A · B = A
r
B
r
+ A
θ
B
θ
+ A
φ
B
φ
(D.92)
A × B =
vextendsingle
vextendsingle
vextendsingle
vextendsingle
vextendsingle
vextendsingle
?r
?
θ
?
φ
A
r
A
θ
A
φ
B
r
B
θ
B
φ
vextendsingle
vextendsingle
vextendsingle
vextendsingle
vextendsingle
vextendsingle
(D.93)
Dyadic representation
ˉa = ?ra
rr
?r + ?ra
rθ
?
θ+ ?ra
rφ
?
φ+
+
?
θa
θr
?r +
?
θa
θθ
?
θ+
?
θa
θφ
?
φ+
+
?
φa
φr
?r +
?
φa
φθ
?
θ+
?
φa
φφ
?
φ (D.94)
ˉa = ?ra
prime
r
+
?
θa
prime
θ
+
?
φa
prime
φ
= a
r
?r + a
θ
?
θ+ a
φ
?
φ (D.95)
a
prime
r
= a
rr
?r + a
rθ
?
θ+ a
rφ
?
φ (D.96)
a
prime
θ
= a
θr
?r + a
θθ
?
θ+ a
θφ
?
φ (D.97)
a
prime
φ
= a
φr
?r + a
φθ
?
θ+ a
φφ
?
φ (D.98)
a
r
= a
rr
?r + a
θr
?
θ+ a
φr
?
φ (D.99)
a
θ
= a
rθ
?r + a
θθ
?
θ+ a
φθ
?
φ (D.100)
a
φ
= a
rφ
?r + a
θφ
?
θ+ a
φφ
?
φ (D.101)
Di?erential operations
dl = ?r dr +
?
θrdθ +
?
φr sinθ dφ (D.102)
dV = r
2
sinθ dr dθ dφ (D.103)
dS
r
= r
2
sinθ dθ dφ (D.104)
dS
θ
= r sinθ dr dφ (D.105)
dS
φ
= rdrdθ (D.106)
? f = ?r
?f
?r
+
?
θ
1
r
?f
?θ
+
?
φ
1
r sinθ
?f
?φ
(D.107)
?·F =
1
r
2
?
?r
parenleftbig
r
2
F
r
parenrightbig
+
1
r sinθ
?
?θ
(sinθF
θ
)+
1
r sinθ
?F
φ
?φ
(D.108)
?×F =
1
r
2
sinθ
vextendsingle
vextendsingle
vextendsingle
vextendsingle
vextendsingle
vextendsingle
?r r
?
θ r sinθ
?
φ
?
?r
?
?θ
?
?φ
F
r
rF
θ
r sinθF
φ
vextendsingle
vextendsingle
vextendsingle
vextendsingle
vextendsingle
vextendsingle
(D.109)
?
2
f =
1
r
2
?
?r
parenleftbigg
r
2
?f
?r
parenrightbigg
+
1
r
2
sinθ
?
?θ
parenleftbigg
sinθ
?f
?θ
parenrightbigg
+
1
r
2
sin
2
θ
?
2
f
?φ
2
(D.110)
?
2
F = ?r
bracketleftbigg
?
2
F
r
?
2
r
2
parenleftbigg
F
r
+
cosθ
sinθ
F
θ
+
1
sinθ
?F
φ
?φ
+
?F
θ
?θ
parenrightbiggbracketrightbigg
+
+
?
θ
bracketleftbigg
?
2
F
θ
?
1
r
2
parenleftbigg
1
sin
2
θ
F
θ
? 2
?F
r
?θ
+ 2
cosθ
sin
2
θ
?F
φ
?φ
parenrightbiggbracketrightbigg
+
+
?
φ
bracketleftbigg
?
2
F
φ
?
1
r
2
parenleftbigg
1
sin
2
θ
F
φ
? 2
1
sinθ
?F
r
?φ
? 2
cosθ
sin
2
θ
?F
θ
?φ
parenrightbiggbracketrightbigg
(D.111)
Separation of the Helmholtz equation
1
r
2
?
?r
parenleftbigg
r
2
?ψ(r,θ,φ)
?r
parenrightbigg
+
1
r
2
sinθ
?
?θ
parenleftbigg
sinθ
?ψ(r,θ,φ)
?θ
parenrightbigg
+
+
1
r
2
sin
2
θ
?
2
ψ(r,θ,φ)
?φ
2
+ k
2
ψ(r,θ,φ)= 0 (D.112)
ψ(r,θ,φ)= R(r)Theta1(θ)Phi1(φ) (D.113)
η = cosθ (D.114)
1
R(r)
d
dr
parenleftbigg
r
2
dR(r)
dr
parenrightbigg
+ k
2
r
2
= n(n + 1) (D.115)
(1 ?η
2
)
d
2
Theta1(η)
dη
2
? 2η
dTheta1(η)
dη
+
bracketleftbigg
n(n + 1)?
μ
2
1 ?η
2
bracketrightbigg
Theta1(η) = 0, ?1 ≤ η ≤ 1 (D.116)
d
2
Phi1(φ)
dφ
2
+μ
2
Phi1(φ) = 0 (D.117)
Phi1(φ) =
braceleftBigg
A
φ
sin(μφ)+ B
φ
cos(μφ), μ negationslash= 0,
a
φ
φ + b
φ
,μ= 0.
(D.118)
Theta1(θ) = A
θ
P
μ
n
(cosθ)+ B
θ
Q
μ
n
(cosθ) (D.119)
R(r) =
braceleftBigg
R(r) = A
r
r
n
+ B
r
r
?(n+1)
, k = 0,
A
r
F
1
(kr)+ B
r
F
2
(kr), otherwise.
(D.120)
F
1
(ξ), F
2
(ξ) =
?
?
?
?
?
?
?
?
?
j
n
(ξ)
n
n
(ξ)
h
(1)
n
(ξ)
h
(2)
n
(ξ)
(D.121)