H xjkc 2 m a πA msnim n a πxco nb πy sejz
hy kc2jhyz exz kc2 k2 2
H yjkc 2 n b πA mc n o m a π sxsin n b πyejz
为什么单导体不能传输TEM波?
x22
y22
z22
k2Et 0
z22etejz 2etejz
2.62a
1.64a
主模, TE11 mode
主模, TE11 mode 激励电场的极化?
边界条件
E(a,)0
E k j c 2 H z jk cA sm i n B cm o J m s ( k c) e j z
kcmnpm na
m n k2 k c 2m nk2p m a n2
cmn
2π kcmn
2πa pm n
fcmncvmn2πapm n
截止波长 3.41a
波导的损耗
d c
d j k c 2 k2k c 2 k2 (1 jta)n
kc2k22jkk 2c2 t akn 2k22 tanj
d
k2 tan 2
Np/m, 奈培每米
量纲是什么?
E (z)E0e dz jz
E(z)E0edz
ln E 0 E (z) dz
ln E 0E (1 )d
2 H z(x ,y ,z ) k 2 H z(x ,y ,z ) 0 Helmholtz 方程
H z(x ,y ,z) h z(x ,y )e jz
t2 z 2 2 h z(x ,y )e jz t2 h z(x ,y )e jz2 h z(x ,y )e jz t2 k c 2h z(x ,y ) 0