Simple FM Radio Receiver Antenna Booster Circuit

Does anyone favorite radio stations ever have static?

Building a signal booster for the radios FM antenna is discussed in this article.

Radio signals are sometimes weak because they travel through the atmosphere particularly if someone reside far from the radio station.

By strengthening weak signals this circuit helps the radio pick them up with more effectively and also reduces static.

Circuit Working:

Parts List:

The BF324 TO92 type PNP transistor is used in this low cost FM radio receiver antenna booster in a grounded base setup.

The circuit serves as a signal booster which is especially useful for VHF receivers with low front end sensitivity including different vacuum tube versions and army surplus kinds.

The frequency range that the preamplifier covers is around 75MHz to 150MHz.

Both of the inductors in the circuit are homemade.

L1 is made up of ten rounds of enameled copper wire, 24SWG with an internal diameter of 3 mm and no core.

Inductor L2 is made up of 13 turns of identical wire that has no core and an internal diameter of 5 mm.

An construction advice :

Temporary formers of 3mm and 5mm drill bits are used to wind the inductors accurately.

The preamplifier prototype works well with a 2 meter VHF ham receiver and an FM broadcast receiver operating from 88 to 108 MHz.

The preamplifier performs well while drawing about 2.5mA from a 5V source.

Formulas:

Antenna signal booster circuit is a device that improves the incoming radio frequency signals to increase an FM radio receivers signal to noise ratio (SNR).

Here is a simple formula and some factors for building an antenna booster for an FM radio receiver.

An essential formula for the LNA is the gain equation which controls the amplifiers gain and the level to which it enhances the input signal:

G = 20log₁₀ ​(A_v​)

where:

• G is the gain in decibels (dB).
• A_v is the voltage gain of the amplifier.

How the formula functions:

It is common practice to use a commercial LNA designed for FM radio frequencies such the Mini Circuits MAR 6 or something like which has a low noise ratio and high gain suitable for FM reception.

The proper LNA with the necessary gain and low noise level is selected in order to create an FM radio receiver antenna booster.

For frequency selection a bandpass filter is used.

By enhancing the antennas weak signals the booster increases FM radio transmission clarity and reduces interference.

How to Build:

To build a Simple FM Radio Receiver Antenna Booster Circuit follow below mentioned steps:

Prepare the Inductors:

• Wind 10 turns of 24SWG enameled copper wire on a 3mm diameter temporary former no core to create inductor L1.
• Wind 13 turns of the same wire on a 5mm diameter former no core to create inductor L2.

Assemble the Circuit:

• Refer to the circuit diagram for the grounded base configuration using the BF324 TO92 transistor.
• Connect the inductors L1 and L2 as specified in the diagram.
• Add the required resistors, capacitors and other components to complete the circuit.

Use Drill Bits as Formers:

• Close wind the inductors by wrapping the wire tightly around the 3mm and 5mm drill bits as temporary formers.

Soldering:

• Solder each component onto the breadboard or PCB with care by following the circuit schematic.
• Ensure that there are no solder gaps or loose connections.

Connect the power source:

• Connect the circuit to a 5V power source.

Testing:

• Use a 2 meter VHF ham receiver and an FM broadcast receiver operating between 88 and 108 MHz to test the preamplifier.
• Be sure the circuit uses the 5V supply at a rate of about 2.5mA.

Modifications:

• If required adjust the circuit to meet standards performance

Note:

When using soldering tools and electronic components keep in mind to take safety precautions.

Seek help from an experienced person if any one is unfamiliar with electronics or look for advice from electronic experts

Conclusion:

An FM radio receiver antenna booster circuit can be built and installed to increase the receivers performance at a reasonable cost particularly when a stronger signal is required for clear and interference free reception.

References:

Datasheet BF324