I see a fundamental flaw. Earth's curvature means point to point LOS is limited to about 38 miles, Ive seen up to 53miles work on commercial microwave sites at a max. This was mountaintop to a 500 foot building in a distant city. Power was 5 watts both ends, antennas were 48db, 10' dishes, space diversity was utilized, (AND needed). Freq 6 ghz.
Youre 70 mile path is way over this for a single hop solution. Either that, or youre shooting mountaintop (possibly) to mountaintop or to where ever.


Im not seeing this working primarily due to power being much lower, antenna gains lower, and the excessive path length.

Im not saying it can't work, havent run the numbers, but I'm highly skeptical.




At 06:32 6/3/2003 +0000, you wrote:
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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