which will cover more distance: Low or high Freq. signal??

[yousif]

Look, Baseband Signal Can travel long distances as you want based on :
1-Signal Power: The More Power the Longer distance
2-Propagation Channel: free space, Cables, Optical Fiber, ...
3-Baseband Signal Frequency: The More Frequency the more Attenuation and Distortion the less the distance.

But:
In almost all communication systems, multiple Baseband signals at the same frequency band need to be transmitted on the same channel, so to prevent interference between signals; Modulation is required which means shifting the baseband signal by the value of carrier frequency and changing the carrier frequency for each signal so that no overlap occures between baseband signals.

so, distance is not intended here by modulation, on the contrary, increasing frequency makes the signal more subject to degredation factors than in low frequency case.

 

[ayan_ns]

I think high freq signal is best for long-haul communication, because the loss of the signal in the medium inversely proportional to the freq, so higher the frequency lower the loss/attenuation the signal will face during travelling thru' medium.

 

[cheggy]

Re: which will cover more distance: Low or high Freq. signal

Loss of the signal is directly proportional to the frequency. Anyway, yousif said it already.

 

[3od]

Re: which will cover more distance: Low or high Freq. signal

the high frequency signal covers more distance because it is more directive.

 

[Naveed Alam]

Re: which will cover more distance: Low or high Freq. signal

If someone write here any formula/equation showing frequency and covered distance relation, things will be clear.


Regards,
Naveed

 

[cheggy]

Re: which will cover more distance: Low or high Freq. signal

EM wave attenuation due to free space loss is:

L[dB]=92.4+20log f + 20log D

f stands for freq. in GHz, and D for line-of-sight distance between antennas in km.

 

[Naveed Alam]

Re: which will cover more distance: Low or high Freq. signal

if the we consider the above equation right, then with high frequencies travel less than low frequencies...



Naveed

 

[spikeyang]

Yes, low frequency travel further. But low frequency antenna is hard to make, antenna dimension reason.