I would like to ask your opinion regarding this matter:

Based on the relation of frequency and wavelengths, the higher the frequency, the shorter the wavelengths and therefore the distance of travel is lower. Assuming two frequencies from the ISM band: 2.45GHz and 5.8GHz.With the same amplitude and antenna gain, the frequency of 2.45GHz will travel further than the 5.8GHz based on their wavelengths.

However, in this link under the subtopic of frequency, it is mentioned that


"In general, the higher the frequency, the greater is the range. RF radiation has more energy at the higher frequencies."

In this case, the range does depend upon the both the transmitter power and operating frequencies. Does it suggest that higher frequencies have naturally higher amplitudes which may cause them to travel further or higher frequencies needs to be supplied with sufficient transmitting power in order to improve its distance compared to lower frequencies ?


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    $\begingroup$ Both statements are equally wrong. The difference in effective distance for these technologies is simply a function of the environment they are being used in. Lower frequencies get attenuated less by walls etc. and they suffer less from interference than higher frequencies. All else being equal (which means proportionally larger antennas for the 2.4GHz band), the free-space line of sight distance would be the same, but that's rarely how these systems are being used. $\endgroup$ – CuriousOne May 29 '15 at 4:29
  • $\begingroup$ Ok. So basically if two systems, one with operating frequency 2.45GHz and the other with operating frequency 5.8GHz, under the same parameters(antenna gain, transmitting power, environment, etc) theoretically, the lower frequency will travel further. Please correct me if I'm wrong. $\endgroup$ – user3156387 May 29 '15 at 5:39
  • $\begingroup$ I believe that to be the case for these frequency bands and for the usual architectural materials in use (wooden frame/masonry/concrete construction), but that's a materials property, not a fundamental property of electromagnetic waves. $\endgroup$ – CuriousOne May 29 '15 at 6:05

In general, the higher the frequency, the greater is the range. RF radiation has more energy at the higher frequencies

That's not correct as stated. Yes, higher frequency photons have more energy than low frequency photons. But your transmitter isn't counting photons. You can have a $1W$ transmitter at low or high frequencies. The high frequency transmitter will produce fewer photons per second, but radiate the same total energy.

The range of radio signals depends on many things including elements of the equipment (antenna, filters, etc.) and the environment (scattering, absorption). While the statement about higher frequency having greater range may be true in the context of normally-available RFID systems, it's not true in general.

  • $\begingroup$ Ok. If I consider the fundamentals in terms of wavelengths, I understand that the range of higher frequencies are lower compared to lower frequencies. RFID systems which claims that higher frequencies produce greater range maybe referring to the inclusion of equipment. But if we compare two RFID systems(with the same parameters and environment) each with different frequencies, I believe the system with the lower frequency will have a greater range. Please correct me if I'm wrong. $\endgroup$ – user3156387 May 29 '15 at 5:46

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