How to increase FM radio signal ? any desgin ?

How to increase FM radio signal ? ,
any antenna booster circuits design ?
what is mean by Low Noise Amplifier (is it called antena signal booster like tv Booster ) ?

any circuit reference ?

thanks in advance

thannara123 said:

How to increase FM radio signal ? ,
any antenna booster circuits design ?
what is mean by Low Noise Amplifier (is it called antena signal booster like tv Booster ) ?

any circuit reference ?

thanks in advance

Click to expand...

you can increase the sensitivity of you receiver by
using an RF amp. before the antenna,
but its best to get an antenna with more gain.
LNA means low noise Amplifier.

Because of back ground noise it is reckoned that
an RF LNA with say 1-3dB Noise Figure is adequate
at VHF FM, the back ground noise decrees with frequency so at Microwave frequencies a very low noise figure front end is Beneficial (.1 to 2db NF).

can you elaborate ? ...
i want to make a booster circuit attached with the antenna .. ?
LNA is called as anteanna booster ?

- - - Updated - - -

i want to desgin that booster circuit any reference or guidelines ?

what frequency is you fm receiver?

Frequency 88 MHz to 108 Mhz .

hi,
if you can hear the station of interest it may be possible
to improve the signal strength by using an antenna, such a slim-Jim
which is easy to make up. (search the WWW for the 'SLIMJIM' construction and also RF amp using Dual gate MOSFETs) you could get about 6db gain from this type of antenna and 20dB gain from the RF amp.
or of course you could buy an FM antenna, but don't buy the halo type ones, as they have a loss of about 6db instead of again.

note :
the slimjim antenna would be about 4Mtrs in length

I need to construct a booster circuits ..:-?
Like this ..http://www.electronicecircuits.com/electronic-circuits/fm-booster-active-fm-antenna-amplifier

A high quality hi-fi FM receiver already has a high gain RF amplifier to be extremely sensitive. If another RF amplifier is used then the receiver simply gets amplified noise.
I agree that a high gain Yagi antenna can increase the signal strength.

the booster amp circuit you show is not that good,
i would use either the Dual gate MOSFET, or a transistor
connected in common base, and an rf choke at the collector
the input is then applied to the emitter, you can then use an
emitter follower to match the output impedance.
or just buy a MINI-CIRCUIT RF AMP MAR6 say and use that.

THINKER_KAM_MAN said:

i would use either the Dual gate MOSFET, or a transistor
connected in common base, and an rf choke at the collector
the input is then applied to the emitter, you can then use an
emitter follower to match the output impedance.
or just buy a MINI-CIRCUIT RF AMP MAR6 say and use that.

Click to expand...

Can i get more details ?

i have simulated a circuit that you may try using multisim
simulation software. the gain is about 10DB

if you want to bootstrap the circuit change R4 value to
470R and R8 value to 47K and connect R8
between Q1 base and Q2 emitter instead.

see below.

i have simulated a circuit that you may try using multisim
simulation software. the gain is about 10DB

Click to expand...

Your circuit as is will only have any gain around 1 MHz. The gain at 100 MHz will be lower than -30 dB.

what changes need ?
How do i get a flat gain for 88-108MHz

Just a suggestion

The amplifier is intended to be a wide band amplifier (20MHZ band width)

The transistor Q1 is a common base amplifier
The collector current is adjusted to obtain 50R
Input Z. the gain of Q1 can be between 10 and 20DB
(depends on the transistor) the 1mH L1, is an RF choke a lower value could be used) transistor Q2 emitter, follower is used to match the output Z.

The simulator shows at 98Mhz, at 1mv i/p
O/P = 20.3mv , so V gain = 20. = ratio.
As db power gain = 10log(vout/vin)
Gain = 13dB. On the simulated scope
It shows the output to be correct.
the output level is approx -21dbm

Q2 could be left out, but a transformer
Or a matching circuit would be required.
To match the collector output impedance
A matching transformer could be made
Up using ferrite beads.

Well you know what simulators are like
But I do know that the common base rf amp
Works well, its easy to build, its stable, easy to
Match input z, can handle large input signals,
Easy to apply gain control, Was used in TV, FM,
Radio and RF amps front ends before FETS
came along.

If you don’t want to build a discreet RF amp
I suggest you use a MINI-CIRCUIT 3 terminal
IC RF amp, (may be, MAR-6) they work from
DC-2GHz 20db Gain. Used a lot in set top tv
antenna Booster.

Here is an old design (if you can still get hold of some BFY90's) that gives 10dB gain in the required band.

thannara123 said:

How to increase FM radio signal ? ,
any antenna booster circuits design ?
what is mean by Low Noise Amplifier (is it called antena signal booster like tv Booster ) ?

any circuit reference ?

thanks in advance

Click to expand...

Hi,
Why do you need an antenna amplifier ?
Long distance to transmitter ?
Most receivers today are so sensitive that an amplifier is not needed.

Can you be more specific and detailed so we can help you ?

I have built many FM antenna amplifiers but that was in 1976-1978.
regards

Nils

The cheap FM radio from The Dollar Store picks up only very strong local stations. If it uses a high gain external antenna or an RF amplifier then it becomes very overloaded by the local stations so it cannot receive weak distant stations.

haaa, now we are talking about signal to noise.

0.2uV for 10DB would be good
but only expensive FM tuners can do that and if your tuner spec
is that then the amp won't help you would need a better antenna.
but most FM tuners are about 1 to 2 uV for 10db quieting and it really depends the RF amp if any used before the Mixer
modern FM Tuners are not that good, i think, as they expect strong signals. from local transmitters. system.

More Spec : I want to use an antenna at top about 10 -15 meter .only there can get fm signal clearly at which that singal need to capture and transmit to the radio.....
so i need a amplifire at the place of antenna..

do you receive a strong signal?
will you be using coaxial to connect to the radio?
if so you can buy FM distribution amps to do that
they are quite cheap and just plug and play.

you may also recover the audio and transmit the signal
using wireless speakers.

also if you can not pick up the signal of interest
at the desired location you might be able to re-radiate the signal locally for that you will need more than
10dB of stable gain.