Transmitter range from output power

[suniljha]

Few weeks before I have posted my query for calculating transmitter range in distance from output power in dbm. I received reply with a very good calculation for it. I need it now but the post is not there. Can anyone help me in finding older postings or please post the reply again.<p>Looking for urgent help..
Thanks,
Sunil

[dyarker]

Try "search" at top right of page. Another way is to increase the number of days displayed.<p>[ May 30, 2004: Message edited by: Dale Y ]</p>

[Externet]

Hi.
If the transmitter puts out +14dBm;
and the coaxial loss is 4dB;
You are left with +10 dBm;
And if the antenna has a gain of 6dB;
The radiated power is +16dBm.
The loss trough the air space from transmitter antenna to receiving antenna is:
L(loss)=20LogD + 20 LogF +32.3
Where D =distance in miles
and F = frequency in MHz<p>Substract that L figure from +16dBm and you will get the signal power reaching the receiver antenna.
Example: at 150MHz; 100 miles; L(loss) = 115.7 dB
The example yields -99.7dBm reaching the receiving antenna.<p>If the receiving antenna has a gain of 3dB; add them:
-99.7 + 3 = -96.7 dBm
If the receiving coaxial has 5 dB loss,
-96.7 and - 5 = -101.7 dBm<p>If the sensitivity of the receiver is better than -101.7 dBm; you get communication.<p>In other words, add all gains and substract all losses to find the total signal level.
You will have to translate 5 miles = to 8 Km.; I do not have the metric formula.<p>A few equivalences for 50 Ohm systems:
2µW = -27 dBm
1mW = 0 dBm
2W = +33 dBm
32W = +45 dBm
1KW = +60 dBm<p>Miguel

[bridgen]

I don't want to tread on your toes Miguel, but I would like to add the following.<p>A non-directional antenna will radiate equally in all directions. A directional one concentrates the energy in only one direction and hence give the effect of gain, relative to a non-dirctional antenna, in that particular direction.<p>In you example it isn't the radiated power which is 16dBm, it is the equivalent radiated power, or e.r.p. <p>Regards.

[Externet]

Yes, David.
The antenna gains taken in account are the ones in the direction of interest.
A 6dB example gain in an antenna is in the direction of aiming; the same antenna can show a loss in another direction but not taken in account as effective radiated power e.r.p. for the calculation of the path.
Miguel

[suniljha]

Thanks a lot for all your responses and posting details again.<p>Sunil