txpwr with 4 antennas instead of 3

[paraplu]

Maybe somebody could verify this: 4-antenna Quantenna AP's, like ac87u, r7500 or e8350, have less range due to reduced power per antenna, as they have to commit to regional regulations of total (all antennas combined) transmit power. Which means less tx power per antenna compared with the older 3-antenna routers.

Is this a right assumption?

 

[L&LD]

That assumption may be valid during a connection to a 4 stream client (or another RT-AC87U, for example, in Bridge mode).

But for the normally available 1 / 2 / 3 stream clients currently available, I would guess that the assumption would be false.

 

[stevech]

Maybe somebody could verify this: 4-antenna Quantenna AP's, like ac87u, r7500 or e8350, have less range due to reduced power per antenna, as they have to commit to regional regulations of total (all antennas combined) transmit power. Which means less tx power per antenna compared with the older 3-antenna routers.

Is this a right assumption?

In the US and some other regulatory domains, the effective radiated power limits vary according to antenna beamwidth. The US rules all, as I recall for 2.4GHz, 4 watts max with a narrow-beam antenna (e.g., 7 degrees or so, as in a dish or long yagii). The concept for spectrum sharing is that as the beamwidth narrows, the power can increase as the interference potential is reduced.

Switched-beam antennas... I don't think the regulations have changed for this time-dependent effect.

To me, the regulations have been fuzzy for a common case of bridges and point to multipoint where the base station uses wide beamwidth (omni or sector) and the clients use narrow-beam. It's common to see a base station with, say, 8dBi gain antennas and clients with 20-30dBi antennas, and be legal (usually in the 5.8GHz band).