BC-91

Antiparasitic filters generally operate by impedance mismatch within a given frequency range.

The insertion loss of a filter in a supply or transmission circuit is defined as the ratio between the voltage values occuring at the line terminal leads immediately after the insertion point, before and after insertion.

Different standards specify the attenuation measurement possibilities in asymmetric (common mode) or symmetric (differential mode)
attenuation, measurements performed on load or no-load circuits.

The following standards are applicable :

• Standard GAM T 21
• Standard MIL STD 220 C
• Standard CISPR

The insertion loss performance is specified, measured according to the standard GAM T 21 or MIL STD 220 C in no-load conditions under an impedance of 50. 

This measurement enables to check the compliance of the manufactured batch and to compare certain filters.
The real efficiency of a filter on an equipment can only be obtained by disturbance measurement taking into account the source and operating impedance.

For signal or data transmission filters usually defined in matched impedances, attenuation in the pass-band is measured according to the standard MIL 18327 E.

As well as the products given, Exxelia proposes a wide range of filtes and EMC protections for applications such as :

• High power
• Ancillary circuits and small signals
• Tempest
• NEMP-HA