GW Instek GRF-3300 Series Student Manual - Manual (Page 15)

16 Microstrip Line Filters
3 323
After that, we can use the follow equation to evaluate the even and odd mode of
the characteristic impedance.
> @
> @
2
0 0 0 0
2
0 0 0 0
1
1 0
1
0
1
1 0
1
1
2
2
2
JZ JZ Z Z
JZ JZ Z Z
g g
J Z
g g
J Z
g
J Z
o
e
N N
N
N N
N
'
'
'
S
S
S
we can get:
86 . 38
36 . 72
35 . 43
15 . 59
86 . 38
36 . 72
335 . 0
158 . 0
355 . 0
3 0
3 0
2 0
2 0
1 0
1 0
3 0
2 0
1 0
o
e
o
e
o
e
Z
Z
Z
Z
Z
Z
J Z
J Z
J Z
Due to the complexity of calculating the coupling coefficiency, we can use CAD
tools to find out the gap between coupling lines. The list below shows the results after the
calculation:
x
3 1
l l
=17.45mm
x
3 1
w w 1.11.94mm
x
3 1
s s
=0.26mm
x
2
l =17mm
x
2
w =2.2mm
x
2
s =1mm