I purchased a Teltonika PR1KCL25 combo MIMO antenna that has two integrated RF174 cables that are 3.0 m (10-ft) each in length. The specified gain for this antenna is 2.5 dBi for the main and 2.0 dBi for the aux.
Wouldn’t the losses from this length of RG174 cable be greater than the gains from the antenna? Or would the specified gains have accounted for these losses?
The concept of antenna “gain” is largely a measure of how directional/focused an antenna’s radiation pattern is, relative to a theoretical model that has no directional character at all. In other words, an indication of how carefully an antenna needs to be aimed. How efficiently an antenna radiates the power applied to it is also a factor.
This differs subtly from the concept of cable loss, which involves how much of the power one puts into a cable at one end actually comes out the other end rather than getting turned into heat.
The toll one pays to get a signal at ~1GHz through 3m (10’) of RG174 is about half of the signal power. Not great, but balanced against the hassle of trying to deal with fatter cables in the suggested use context, it’s probably a fair trade.
In this case, the figure would appear to indicate that the antenna is sufficiently directional so as to come out a few dB ahead of the (non-directional) isotropic (the ‘i’ part of dBi) antenna, after losses associated with the cable are accounted for.
