Multipath dependence over frequency

[andrishev]

Hi everybody,

i could not find any clue about frequency dependence of multipath phenomena,
but, i am expecting that at high frequencies (over 2 GHZ up to Ku band) multipath
is more problemetic than at low frequincies ( 400MHz eg.)

Has anybody an idea about this.

also, what is the worst effect of multipath to a receiver; degrading the signal below the receiver sensitivity or inter symbol interferance (ISI) effect.

thank you.:|:?:

 

[realbaltalyus]

Hi Andreshev,
We are working this kind of work with my collegue.
But my man we must work hard.
with my cordial regards
See You

Added after 4 minutes:

Of Course my man the answers of your problems;
ISI is the big problem for multipath,
The power receiver sensitivity can be beat by amplifying the signal.
Also some signal degradation cause of rain or snow in Ku band can be omitted by increasing the signal power
See you man

 

[Rf engineer]

multipath fading is not a function of frequency.....

however it causes ISI for the receiver.............

as multipath causes multiple copies of the same message arriving at different times at the receiver hence interfere with the just arrived symbols.....causing inter symbol interference..........

so multipath has ISI as major impairment.............

hope that answers the question

 

[rfmw]

I'd say multipath has a higher effect at low frequencies, since high freq links use high-directivity antennas (>25 dBi).

 

[andrishev]

Thanks for your answers...

So, is it the only region that multipath has higher effects at lower frequencies because of antenna directivities (geometry)....

or, can we say also at higher frequecies, for example reflection from ground will be lower at higher frequencies (reflection constant) etc..

have a good day :|

Added after 7 minutes:

one more thing...

i am planning to make a channel sounding ( direct RF pulse measurement) for a system with one omni directional antenna at receiver site and a directional antenna (>19dBi) at transmitter site.

Has anybody experience on channel sounding.

thank you.