FM noch filter for HackRF One

Hello everybody. Very close to me is a powerful FM radio station, it sims that it affects on the sensitivity of HackRF One, so the idea came to make a notch filter FM band.

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Schematics of FM notch filter

This is a four-circuit filter. The coils are wound with enameled wire 1 mm diameter, the winding diameter is 5 mm. coils L1, L2 – 2 turns, L3 – 12 turns, L4 – 14 turns, tuning capacitors 5-30 pF, additional capacitors of 82 pF format 0805. L1, C1 – 98 MHz. L2, C2 – 98 MHz. L3, C3 – 108 MHz. L4 C4 – 88 MHz. Estimated level reduction of 30 dB.

View of the board in 3D

Made a case from doublesided FR4.

Paint it.

We adjust the filter to the frequency of the nearby FM station 100.1 MHz with UR5FFR NWT

Testing the results with HackRF One 

Without filter

With filter


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