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FM Bandpass Filters

Rev : 01 | Rev date : 14 Sep 2022

RFS bandpass filters for VHF FM Radio are primarily used in multi-channel combiner systems but can also be used to eliminate spurious emissions and increase isolation between co-sited FM Radio services.
The filters are easily re-tuned in the field, as all tuning adjustments are external and the fixed aperture coupling design is engineered for a constant passband wherever filter is tuned in the band. This design ensures standard insertion loss and response for each filter model, although custom filter performance (modified aperture coupling) is available on request.


  • Invar temperature compensation for stable operation
  • Fixed aperture coupling for high reliability and easy re-tuning
  • Vertically oriented inputs and outputs for simple installation

Technical features

General Specifications

Product LineFilter Radio
Product TypeBand II (VHF) FM Bandpass Filter
Filter Type and Size2 Pole, 400mm

Electrical Specifications

Frequency Range MHz87.5 - 108
Impedance Ω50
Input PowerkW

7.5 (Temp Rise: 30°C)

10 (Temp Rise: 40°C)

10 (Temp Rise: 30°C)

14 (Temp Rise: 40°C)

Insertion LossdB<0.24<0.18
Amplitude ResponsedB

<0.1 at fc ±120kHz

>20 at fc ±1.6MHz

>29 at fc ±2.4MHz

<0.1 at fc ±140kHz

>20 at fc ±2MHz

>29 at fc ±3.6MHz

Return Loss dB

>26 at fc ±120 kHz

>26 at fc ±140 kHz

Group Delayns<40 at fc ±100kHz<35 at fc ±100kHz

Mechanical Specifications

Connectors3-1/8" EIA (unflanged female) (Note 1)
Dimensions (Length)cm (in)86 (34)
Dimensions (Width)cm (in)45 (18)
Dimensions (Height)cm (in)130 (51)
Weightkg (lb)51 (112)

Temperature Specifications

CoolingNatural convection
Max Operating Temperature°C(°F)80 (176)
Ambient Temperature Range°C(°F)-5 to 55 (23 to 131)
Maximum Temperature Rise°C(°F)40 (104)
Humidity%95, non-condensing

External Document Links


  • Note 1. Other connectors are available on request