Wireless N standard uses multiple antennaes (MIMO) to achive higher throughputs. It also supports transmission on different frequencies.
The antennae you specify appears to be a single antenna which wouldn't support the MIMO function so it won't work with N.
Also, antennae types differ - they create different broadcast patterns which affect your signal strengths. Lots of antennaes that say they have higher decibel patterns flatten their patterns. So, if you think of the typical antennae as having a somewhat squashed toroid signal pattern, and the flatten it into more of a pancake type of signal pattern - then yes you get more signal - as long as you realize you are giving up more of the vertical range - so if your WAP is on the third floor and the system is on the first, you may have worse reception. Antennae patterns are too complex to get into - recommend Wikipedia as a starting place to research.