Distances on antennae

[acidrain]

Okay, so ive been looking on the miro website for equiptment and stumbled across an antennae which they give an aprox. distance of 8km.

Would this distance be from point-to-point or would it effectively be only half way. i.e. If i have two (approx. 8km antennae) on both points, would the antennae still be able to pick up the signal at an effective 16km or would it still remain at a distance of 8km? Btw... lets just ignore all the losses involved for now

Dunno if it makes any sense but hey... im still learning here so sorry if its a bit of a noob q!

Thanks

 

[Eben]

Unfortunately it will stay 8kms since it need tx (send) and rx (receive) so both sides have direct influence on each other.

 

[RichardP]

If you get an antenna of 15dbi, Point to point and assuming there are no cable losses and your transmitter runs at 17dbm (50mW) You will get 8KM with a budget of 6dbm (assuming radios are -78dbm sensitivity). Even at 12KM its boderline with a 3dbm spare. (Recomended 6 to 10dbm as a budget as rain fade and such things impact the link)

On 21dbi antennas, you can shoot in excess of 20KM *theoretically*

Keep in mind that this is purely theoretical and it does not take in to consideration the all important noise factor.

http://huizen.deds.nl/~pa0hoo/helix_wifi/linkbudgetcalc/wlan_budgetcalc.html

For example... 8KM for 100% speed... 10KM at 50% speed.. etc etc its all based on Received Signal Strength vs Noise.

 

[acidrain]

Thanks for the input guys. Really find the Link Calculator page useful so thanks again.