antenna-theory.com

[scubasteve]

On this page you say that an important result of the Friis Transmission Equation is the frequency dependence of path loss, that more path loss is seen at higher frequencies.

I disagree with this I believe the frequency dependence has nothing to do with path loss but only the dimensions of the physical antennas themselves. Rather than attempting to pose my argument in this text box I will link here to a great article that I think expertly sums up the issue.

This is something I have been confused about for a while and I feel that the above linked article is correct over your antenna-theory page.

Can you please provide direction as to why I/the article might be wrong in this case? I would be very eager to hear!

[admin]

Yes that referenced article is correct.

A more complete statement for pathloss is that "for fixed gain antennas, the pathloss increases with frequency". But you could also say "for a fixed aperture antennas, the pathloss is constant with frequency".

But whatever you are doing, you should expect more pathloss at higher frequencies. 60 GHz is used for point to point communication over small distances, and much lower frequencies are used for long wave propagation.

[scubasteve]

[coundpake]

You're right, it has nothing to do with free-space loss. If you were designing a communication systems between satellites in space you would just consider different frequencies to propagate equally. However, when in presence of a medium/obstacles (atmosphere, buildings, clothing, trees, etc.) you have to consider how propagation (refraction, reflection, diffraction, absorption, polarization, scattering) changes with frequency. In the RF/MW spectrum these properties usually increase attenuation at higher frequencies.