Active antenna for radio

Active antenna for radio

Here is an active antenna that can be used as an antenna for medium wave, FM and short wave. In the short wave band, the receiving performance of this active antenna is equivalent to that of a 20-30 foot passive antenna.

This antenna can be attached to any portable radio and used in different frequency bands. L1 needs to be selected to suit the needs. The 470uH inductor is very suitable for use in the AM band. If it is a shortwave band, you can try using a 20uH inductor. Of course, in the FM band, a hollow coil with about 10 turns is enough.

This circuit itself consumes very little power. It can use a 9V laminated battery and can be used for a relatively long time. If you are using a power adapter, you need to add a small capacitor between the power supply and the ground as a bypass to eliminate noise interference. A capacitor of about 0.047uF should be suitable for your needs.

The input antenna can use a horn antenna.

Please pay attention when soldering. If it is used in the FM band, shorten the component pins as much as possible during soldering.