Installing a larger antenna on a WiFi router?

[fogeshan]

I've got a Netgear ADSL WiFi router (has two antennae) and a Trendnet 7dB antenna. Can I just replace one of the smaller antennae with the larger one?
Will it improve the WiFi signal or make it worse?
Can it potentially cause any damage?

Edit: here's a picture:
https://goo.gl/photos/N64Ty7p1NYbGVZYF6

 

[Soul Assassin]

You can just replace it, it won't cause any damage. It might not necessarily increase your range but it might improve the strength within the current range.

 

[Jola]

I replaced the three antennas on my Asus RT-N66U.

It did improve the range a bit, but not as much as I had hoped.

However, within the range it works extremely well, except for the 5GHz band, that is useless.

 

[fogeshan]

Does a larger antenna draw more power? Does the router vary the signal strength based on the antenna that's plugged in? Or is it passive?

Jola, maybe interference from the neighbours on the 5ghz band?

 

[Jola]

No, no traffic on 5GHz.

I've just found it to be a useless band because the range is only about 10m max.

I have tried different routers, same with all of them.