Dear friends,
I am confused while calculating a long range wireless link. Could u please check whether it's correct or not and if not then where i am wrong.



This is the mathematics that I have done . Please let me know if it's correct.


( I have assumed no Fresnel Effect and LOS acheivable between the two sites)
The link to be established is 70 miles.


d=70

Equipment :

Access Point Gain 23 db

Receiver Sensivity of the Access Point

11 Mbps <-87dbm
5.5 Mbps <-90dbm
2 Mbps <-93dbm
1 Mbps <-95dbm

Mesh Parabolic Antenna: 21 dbi
Amplifier = 18 dbm


Calculations: Loss in Air = 20 log(d) +20 log (f) +36.6

Assuming f=2437 mhz ( channel 6) , we have,

Loss in Air= 141.2






Gain Between the Radios= Access Point (Gain) + Amplifier + Antenna
=2 * (23+21+ 18 )= 124



Losses= Cable+Connector+Aresstor =2.97+2.97=5.94



Total=Gains-Losses=124-5.94=118.06


Perceived Signal Level= 118.06-141.2=-23.14

Now since it's above the receiver sensivity of the access point, therefore will 11 mbps or atleast 5 mbps be possible.
Is this correct.


But my confusion is that if we increase the length to say 150 miles , then in this case:

Total Signal Loss in Air ( using the same formula)= 147.82
Now using the same equipment all the place, the Total Perceived Signal is :


118.06-147.82=29.76

In this case also, it should transmit at 11 mbps.

I am dead confused.

please help...

Regards and anticipating reply from ur end.
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