I received two of these antennas from a friend. He said they are for wifi, but has no idea on the band.

Looks like dual band. The shorter patches are about 1/4 wave on 5 GHz, the longer ones are for 2.4 GHz.

Oh, interesting. Thanks!
Considering that 2.4GHz is roughly half of 5GHz, would a let's say 5GHz antenna give some reduced performance on 2.4GHz or vice versa?

It would, but don't count on it. It is science, but it is dark science. Remember your engineering courses? Your practice of "connecting an antenna in parallel to an existing one" is totally outrageous.

I was planning on connecting these ones on an older router.
At the moment I did connect in parallel to the dual band ones from the 4300 a set of double biquad omni directional ones, and I must say they work a treat! Best results are with power at 18-19dBm. And the alignment is very important for data speed. I'll try and remove the original two dual band ones from the 2.4GHz line and see if there's any change. The single 5GHz one does the trick very good on the first floor. I get full signal everywhere in the room, maxed at 100mbps.
But I do intend on starting on learning radio. The tinkering I did last few days made me more curious.

(Last edited by bob808 on 5 Nov 2016, 18:13)