This is the circuit diagram of active antenna amplifier for FM radio device. With only a small handfull of parts you can built this trusty FM Amplifier to boost the signal from the radio transmitter. The circuit works with only 1 UHF/VHF type transistor, MFE201. This amplifier will pull in all distant FM stations clearly. The circuit is configured as a common-emitter tuned RF pre-amplifier wired around VHF/UHF transistor MFE201. There are a couple other models that probably would work too, like the NTE107, 2SC2570, etc. but I have not tried it.
Adjust capacitor trimmers C1 and C2 for maximum gain. Input coil L1 consists of 4 turns of 20SWG enamelled copper wire over a 5mm diameter former. It is tapped at the first turn from ground lead side. Coil L2 is similar to L1, but has only three turns. The circuit diagram of active antenna amplifier shows the pin configuration of the coils. Good luck and having fun!
Active Antenna Amplifier Notes
Active antennas are any antennas with integrated signal amplifiers built right into the unit. While, passive antennas are antennas that have no amplification stages.
An active antenna is a passive antenna that simply includes an onboard amplifier. There is no difference between the antenna element of an active or passive antenna of the same type; the only difference is whether an amplifier is included.
Active antennas can be used for both receiving and transmitting applications, but they are most often seen as receiving antennas. When used to receive signal, the integrated amp boosts the RF picked up by the antenna and allows much longer remote cable runs.
