Higher frequency gives further range of transmission?

As I am concerned with RFID technology, when we use higher frequency, the range we can reach is longer.

However, when I come to study about the wifi technology, IEEE.11a, which uses frequency of 5.7GHz,which have a shorter range of transmission compared to IEEE.11g, which only uses frequency of 2.4GHz.

So, I am quite confused whether high frequency gives longer range or not?
Pls enlighten me, thx.

The propagation distance depends by frequency. Double the frequency means 6dB more path loss attenuation.
But in the same time using higher frequencies get more reflections, and also lower dimensions of the antennas which sometimes make them more efficient, and this could be the reason to get better performances for indoor applications.

When the frequency increases, the wavelength decreases. The antenna length is around quarter the wavelength. The disadvantage is the attenuation and losses effects are higher at higher frequencies.
--
Amr Ali
www.embedded-tips.blogspot.com

About the only place you REALLY see performance increase due to antenna size is when you start talking about 60 GHz. There you get sooo much antenna gain, that you really do get good transmission with very low power.

At lower frequencies, like 900 MHz, 2.4 GHz, 5.8 GHz, the antennas are all practically the same size (a little whip sticking out of the box"), so the lower frequency travels the furthest.