FERRITE DEVICES
Technical information / Electrical features
ELECTRICAL FEATURES
All the parameters given in this section (insertion loss, isolation, VSWR, power) are absolute
maximum ratings assured in the operating temperature range.
Typical values are obviously better.
Insertion loss (I.L.)
If a signal is applied at port # 1, it will emerge from port # 2 with a loss characteristic called insertion
loss, which will be the ratio of the output signal to the input signal expressed in dB:
I.L dB = 10 log
10
Typical values: 0.1 to 0.4 dB.
[ ]
P
in
P
out
Isolation
•
For an isolator:
If a signal is applied at port # 2, it will emerge from port # 1 with a high insertion loss called
isolation, which is also expressed in dB (ratio of the output signal to the input signal).
•
For a circulator:
For a circulator, it should be noted that this parameter is not applicable. But it is common to use
this parameter as if the circulator could be made into an isolator by terminating one port (e.g. port
# 3) with a matched load. The isolation measured is dependent on the VSWR of both the
termination and the circulator port.
Typical values: -20 to -30 dB
VSWR
The reflection coefficient magnitude
or circulator (see Fig. 6).
ρ
characterizes the reflective property of each port of an isolator
ρ
=
√
P
reff
P
in
It is useful to use the voltage standing wave ratio (VSWR)
VSWR =
1 +
1 –
ρ
ρ
~
P
in
DUT
P
out
Typical values: 1.07: 1 to 1.25: 1
w
P
reff
FIG. 6
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