To amplify the weak signal received by the antenna, the following antenna booster circuit can be utilized. Usually, antenna for AM/FM is not tuned for the optimal dimension of 1/4 wavelength because we prefer small portable size. This antenna that not yet tuned has very low gain, therefore the antenna circuit booster as the following is helpful to receive better signal.
If AM frequency (700kHz-1.5MHz) is used around 470uH coil for L1, and use around 20uH for SW or FM receiver. For the short wave performance, with this antenna booster you will achieve a strong signal as like what we get from a 20-30 feet antenna. The power supply should be bypassed by a 47nF capacitor to ground, at a point that should be chosen as close as possible to L1.