A Bias T

To power the LNB, we will have to separate the DC power supply voltage and the radio signal, and we must also attenuate this signal which could damage our key (it is possible to buy a ready-made T-BIAS, but it is very easy to make one)
The schematic is simple and only requires a few common components.
The bridge made around the 56 and 330 ohm resistors serves as an attenuator, the 10pF capacitor blocks the DC voltage (The 12V can only go to the LNB side and not to the key), the small choke (coil) blocks the signal receiver which can only go on the receiver side and not in the power supply.

Credits: F1EFW