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How to establish the range of a transmitter?

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halee awan

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hi
my Q is how to find out the range of the TX ,if its transmitted frequency is known ...for e.g lets
a TX has its Tx frequency 466Mhz,its anteena will be 16.09cm long
then how much far it can go with out reasonable power loss
 

Re: range

You have to do a Link Budget analysis (check your system for RX sensitivity).

RX_pow [dBm] = TX_pow [dBm] + TX_ant_gain [dB] + RX_ant_gain [dB] + Free_space_attenuation [dB]

where

Free_space_attenuation [dB] = 27.6 – 20*LOG (frequency [MHz]) – 20*LOG(distance[m])

In this formula increase distance until RX power reach the RX sensitivity, and that is the theoretically maximum distance, which in reality is a little bit smaller due to extra propagation attenuation.

The gain of your λ/4 monopole at 466MHz probably is close to 0dB of gain.
 

Re: range

hi sir
how to find out the gain of anteena mean what is formula to calculate the gain of anteena.and sensitivity of RX unit
 

Re: range

Finding the real gain of the antenna is a different story. This could be simulated or measured (last is preferred in your case).
**broken link removed**
 

Re: range

It is hard to calculate the range by Maths. It is because in real situation mutlipath fading is dominate. Furthermore, the componet like plastic, PCB near the antenna will affect the matching of the antenna. You should consider all the factor for calculating the antenna length.
 

Re: range

For what concerns multipath effect, how do we have to consider it in our link busget? I saw examples where the multipath loss was about - 20 dB... it strongly decreases the Power at the Receiver Antenna...what's your feeling?

Regards,

Lupin
 

Re: range

hi
my Q is how to find out the range of the TX ,if its transmitted frequency is known ...for e.g lets
a TX has its Tx frequency 466Mhz,its anteena will be 16.09cm long
then how much far it can go with out reasonable power loss



To get meaningful results for your question you need to consider three general factors: The source transmitter and antenna, the channel, and the receive antenna and receiver (sensitivity, noise figure, etc). Once you have a handle on those three elements it makes sense to ask how far can you go.

You might also think about and characterize what you mean by "reasonable" power loss.
 

Re: range

Hi,

For example at 5.8GHz with FSK, 600Kbps, +30dBm Transmit power, Receive Sensitivity = -100dBm, 0dBi Antenna Gain (Both Transmit and Receive Antenna Gain) will give line of site range of 350m to 400m for clear talk.

Do the math at 466MHz the path Loss delta = 5800 / 466 = 21.9dB

In real life path loss doubles for every 12dB (not 6dB).

For Monopole Antenna assume = 0dBi gain

You may get close to 1.6Km with 30dBm power at 466MHz with similar Receive sensitivity.
 

Re: range

Hi,

From the last line of your question, shall we assume that Ptx = Prx ?

On free space With Tx CF of 466MHz we know that you're using a quartewave antenna and what we need to do here is to find your antenna effective aperture for both Transmitter and Receiver.

You can then compute the range using Friis transmission formula;

R² = PtxAerxAetx/Prx λ²

Where;

R = distance between antenna (Meter)
Ptx = transmitted power (Watt)
Aerx = effective aperture of receiving antenna (M²)
Aetx = effective aperture of transmitting antenna (M²)
Prx = received power (Watt)

Hope it will help

Good luck...
 

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