Simple FM Radio Receiver Antenna Booster Circuit

Do anyone have a favorite radio station with static sometimes?

This Simple FM Radio Receiver Antenna Booster Circuit talks about how to make signal booster for FM antenna on radio.

Sometimes radio signal are not strong especially if person live far from radio station.

This small circuit makes weak signal stronger so radio can catch better and have less static.

Circuit Working:

Parts List:

This FM radio antenna booster uses one BF324 PNP transistor TO92 type in grounded base setup which is cheap and easy.

Circuit work like signal booster which helps for VHF radios that have weak front part.

It is good for old vacuum tube radios or army surplus ones too.

Preamplifier work from around 75 MHz to 150 MHz.

Both coil inductors in circuit are homemade.

L1 made with 10 turns enameled copper wire, 24SWG with no core and 3mm inside diameter.

L2 made with 13 turns same wire with no core and 5mm inside diameter.

One tip for building:

Use 3mm and 5mm drill bit as guide to make coil easy and correct.

This booster tested with 2 meter VHF ham radio and FM radio of 88 to108 MHz works good.

It uses only 2.5mA current from 5V power.

Formulas:

Antenna signal booster is small circuit that makes radio signal stronger.

It help FM radio to get better sound and less noise by improving signal to noise ratio (SNR).

Here is one easy formula and some points for make antenna booster for FM radio.

Important formula for booster LNA is gain formula which shows how much signal gets it stronger:

G = 20log10(Av)

where:

• G is gain in decibel dB
• Av is voltage gain of amplifier

How it work:

People usually use ready made LNA (Low Noise Amplifier) like Mini Circuits MAR 6.

It works good for FM radio by giving strong signal with low noise.

To make good FM antenna booster we need to choose LNA with right gain and low noise.

Also we use bandpass filter to pick correct radio frequency.

This will help make weak antenna signal more strong and clear for FM radio.

How to Build:

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

Make the Inductors:

• Take 24SWG enameled copper wire.
• For L1 wind 10 turns on 3mm drill bit with no core.
• For L2 wind 13 turns on 5mm drill bit with no core.

Build the Circuit:

• Look at circuit diagram with BF324 transistor in grounded base setup.
• Put L1 and L2 same as diagram.
• Add needed resistors, capacitors and other parts.

Use Drill Bits as Formers:

• Use 3mm and 5mm drill bits to help make coils.
• Wrap wire tight on them to make clean inductor.

Soldering the Parts:

• Solder parts on PCB or breadboard.
• Follow the diagram.
• Check no loose wires or bad solder points.

Connect Power:

• Give 5V power to the circuit.

Testing the Circuit:

• Use 2 meter VHF ham radio or FM radio for 88 to 108 MHz to test.
• Circuit should take about 2.5mA from 5V supply.

Make Changes if Needed:

• If not working good then try change some parts to improve performance.

Be Safe:

• When using solder or electronic parts be very careful.
• If not sure then ask expert person or someone who know electronics.

Conclusion:

This Simple FM Radio Receiver Antenna Booster Circuit can help radio work better.

It is cheap to build and give good result.

References:

Datasheet BF324