Relation between earth radius factor (K) and fresenal zone and Link Distance

[ElMazagangy]

I need to ask about how can I compute the earth radius factor which used in Pathloss, and its relation with requested clearance.

I found some guys compute K=1.33 and F1=100% or in long distance as K= 0.67 and F 60%

How can Specify K and F1 which be used. On what basis can I get this information?

[rm77]

Hi;
i suggest you to have a look to this useful doc already posted here particularly from page 14.
Meanwhile you are using pathloss, for example, you can calculate your diffraction in putting the value of k exceeded 99.9% in worst moth already calcuted by the tool itself (PL5 or PL4).

Thx.

http://www.finetopix.com/showthread....t=Ingvar+Henne

[rm77]

Sorry, i forgot also to say that some of the clearence critera as used in many telecom systems are :
the minimum 1^st Fresnel Zone clearance for K=1.33 shall be 100% for main antennas.
the minimum 1^st Fresnel Zone clearance for K=0.67 shall be 60% for main antennas.
the minimum 1^st Fresnel Zone clearance for K=1.33 shall be 60% for diversity antennas.
the minimum 1^st Fresnel Zone clearance for K=0.67 shall be 30% for diversity antennas.


BR.

[ElMazagangy]

Thanks for your support rm77

I found a graph between the link distance and K factor but now I can't find any about F1 clearance factor.

I have a link distance 60 km I found the K factor around 0.84. Now the question which clearance can be used? and how I choose it.