PRODUCT OVERVIEW
FM broadcast stations operate at some of the highest power levels of any terrestrial transmitter, and wideband receivers have essentially no built-in protection against them. When a receiver's front end is saturated by FM energy, the result isn't just poor FM reception — it's degraded performance across frequencies that have nothing to do with FM radio. Signals you should be receiving cleanly get buried under noise generated by a band you never intended to tune.
This filter removes that problem at the source. A 7th-order FM notch design delivers 72 dB of peak rejection across the 88–108 MHz FM broadcast band, while passing signals above 118 MHz with less than 0.5 dB of insertion loss. That asymmetric response was deliberately engineered for airband reception in the 118–136 MHz range, where FM overload is the single most common cause of degraded performance, though it works equally well for SDR setups, ADS-B receivers, VHF monitoring, and any signal chain where FM broadcast interference is a problem.
The filter is housed in a sturdy plastic enclosure with SMA-F connectors, sized for permanent installation at an antenna connection point, on a mast, in a vehicle, or anywhere the signal chain needs a reliable, mechanically protected inline component. It operates to 3 GHz with under 1.5 dB of insertion loss outside the FM band, and handles up to +30 dBm (1 Watt) of RF input, making it suitable for transmit-path use as well as receive-only applications.
ATTENUATION TABLE
| Frequency | Typical Attenuation |
|---|---|
| 50–80 MHz | < 0.5 dB |
| 90 MHz | 52 dB |
| 100 MHz (FM band centre) | 72 dB |
| 110 MHz | 6 dB |
| 120 MHz | 1 dB |
| 130–200 MHz | < 0.5 dB |
| 200–2700 MHz | < 1.5 dB |
| 2700–3000 MHz | < 4.0 dB |
APPLICATIONS
- Permanent mast-head or outdoor antenna installation requiring mechanical protection
- Fixed amateur radio or SDR shack setups where a bare PCB isn't practical
- Vehicle or portable station use where the filter will be connected and disconnected repeatedly
NOTES
- SMA-F connectors
- Maximum RF input: +30 dBm (1 Watt)
- Compatible with both North American FM (88–108 MHz) and Japanese FM (76–95 MHz) broadcast allocations
- Need bare-PCB format? See the FM Notch Filter for Airband Applications ($29.10)
- Need higher rejection? See the FM Notch Filter 88-108MHz; Excellent Rejection 85dB ($29.10)
FROM THE FIELD
