FERRITE DEVICES
Technical information / Electrical features
Load VSWR
Power rating of a ferrite device depends on the mismatch at the output port (load VSWR); for instance,
for an isolator, if load VSWR is 2: 1, more than 10% of the input power is reflected inside the ferrite
device to the internal load.
In case of short-circuit (infinite load VSWR), the ferrite device has to handle the equivalent of twice
the input CW-power, and the equivalent of a peak power equal to 4 times the input power, based on
the higher internal voltage levels.
Therefore, the time-duration of short circuit or high load VSWR is needed in order to determine an
adequate safety margin.
Third order intermodulation products (IMP32)
Harmonics and third order intermodulation products appear when non-linear elements are used such
as ferrite materials, metal welds, surface finish, etc.
When two tones - F
1
and F
2
- are applied to a ferrite device, the relative amplitudes of 2F
1
- F
2
and
2F
2
-F
1
are critical in some communication systems and should be specified when ordering (see Fig. 8).
POWER
P1
IMP
32
P2
P
IM3
2F
1 -
F
2
F
1
∆
F
F
2
2F
2 -
F
1
FREQUENCY
FIG. 8
•
Test conditions (to be specified)
-
-
•
F
1
and F
2,
P
1
and P
2
in W or dBm.
Third order intermodulation products
-
-
P
IM3
in dBm or,
IMP
32
= P
IM3
- P
1
in dBc.
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Vol. 1
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