link path - calculating the power received problem

[liberal]

link path

when we calculate free space loss,we use formula FSL=32.4+20logf+20logd,any condition about this formula?
now ,i have a system planning.transmiter antenna's height Ht,receiver antenne's height Hr ,transmiter EIRP is Pt+Gt,receiver Gain is Gr,distance is d,the frequency is f (about 400MHz),when i calculate the power received,can i use the formula above,and write the power received as Pt+Gt-FSL+Gr?what about the reflection of the ground?

 

[DDavid]

Re: link path

hi

like I remember Friis formula is for Gt=Gr=1dBi, Ht=Hr
When you are using with different model Friis changes,
exact changes you can find in Rapaport or Goldsmith books.
Also Friis consider n=2

I attached a few pages from Goldsmit
David

 

[vfone]

Re: link path

In your link path formula have to take in consideration also the fade margin.
Generally a value of 20dB is used for fading margin, but this is dependable by environment, frequency, etc.