Difference Between Gain of Different Frequencies with Integrated Omnidirectional Antennas

[UncleJP]

Here is a quote from some ENCOR material:

Integrated omnidirectional antennas typically have a gain of 2 dBi in the 2.4 GHz
band and 5 dBi in the 5 GHz band.

Why is it that the lower frequency has less gain than the higher frequency?

Any input is appreciated.

[Joseph W. Doherty]

Might have to due with signal absorption and/or signal reflection from other items in the environment.

[UncleJP]

I do not think so. This is just the baseline gain from the antenna radiation.

[Joseph W. Doherty]

Well that's possible too assuming the antenna is more suitable for 5 GHz vs. for 2.4 GHz (recall any antenna is only really optimal for one wavelength/frequency [https://en.wikipedia.org/wiki/Standing_wave_ratio]).

[Leo Laohoo]

When the power gain are set equally, 2.4 Ghz can push further than 5.0 Ghz.
NOTE: I am talking about when the setup is in a wide open field and the nearest WiFi interference is 100 metres away.
The probably reason why the antennas power gain is/was designed like that is to ensure that at a certain distance, the RSSI of the 2.4 Ghz and 5.0 Ghz are equal.