I had this ingenious idea of getting an external antenna for increased service coverage.
1st up, netgear factory piece ordered from amazon. It came in a package, with an interesting tag, "demo unit". It did absolutely nothing, nada... back to amazon it went.
2nd, two whip antennas. Not only did it not improve signal strength, speed test showed a 20% drop in data transfer speed.
Talked to the smartest electrical engineer I know, he said even with the short (12") coax, the signal loss on that cable may overcome any advantage I might get out of the antenna.