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FM Low Pass Filter

Rev : 02 | Rev date : 30 Aug 2021
  • The RFS LPF low pass VHF FM filter provides a minimum of 30dB rejection at 211.4MHz and 45dB at 317.1MHz.
  • A custom designed structure, this filter is used to create a very sharp cut off rate and to maintain high rejection.  The cut off frequency is 110MHz.
  • High quality material is used leading to high power handling capability and very low insertion loss.  The external appearance is aluminium metallic.
  • With the low pass filter installed, a broadcast FM transmitter can operate safely in co-location with other wireless services.


  • 12kW power handling capability
  • Low insertion loss
  • Sharp cut off rate

LPF31B Low pass VHF FM filter

Technical features

General Specifications

Product TypeBand II VHF FM Low Pass Filter
Technical ApplicationHarmonic suppression

Electrical Specifications

Impedance Ω50
Pass BandMHz75 - 108
Pass band Return Loss dB>25
Pass Band Insertion LossdB≤0.1
Stop band rejection dB>30dB @ 211.4 MHz
>45dB @317.1MHz ≤f ≤422.8MHz
Power HandlingkW12kW ISDB-Tsb (PAR = 10dB) (10 x log (Ppk/Pav)

Mechanical Specifications

Connectors3-1/8" unflanged1-5/8" unflanged
(with AD31-16 adaptor)
NAX39D unflanged
(with AD31-NAX39D adaptor)
Dimensions79.4mm diameter x 1214mm41.3mm diameter x 1445mm41.3mm diameter x 1445mm

Temperature Specifications

Temperature Range°C (°F)5 to 45 (41 to 113 )

Typical attenuation

External Document Links


Maximum temperature rise 15ºK
Maximum operating temperature 60ºC