This is a design circuit for active antenna that can be used for AM, FM, and shortwave (SW). This is a simple design circuit. This is the figure of the circuit.
On the shortwave band this active antenna is comparable to a 20 to 30 foot wire antenna. This circuit is designed to be used on receivers that use un-tuned wire antennas, such as inexpensive units and car radios. L1 can be selected for the application. A 470uH coil works on lower frequencies (AM). For the short wave, try a 20uH coil. The unit can be powered by a 9 volt battery. If a power supply is used, bypass the power supply with a .04uF capacitor to prevent noise pickup. The antenna used on this circuit is a standard 18" telescoping type. Output is taken from jack J1 and run to the input on the receiver.
On the shortwave band this active antenna is comparable to a 20 to 30 foot wire antenna. This circuit is designed to be used on receivers that use un-tuned wire antennas, such as inexpensive units and car radios. L1 can be selected for the application. A 470uH coil works on lower frequencies (AM). For the short wave, try a 20uH coil. The unit can be powered by a 9 volt battery. If a power supply is used, bypass the power supply with a .04uF capacitor to prevent noise pickup. The antenna used on this circuit is a standard 18" telescoping type. Output is taken from jack J1 and run to the input on the receiver.
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