I'm looking to improve a friends indoor wireless signal. He has a D-Link DI-514 with a PCMCIA card on his laptop. It has a 15dBm antenna. I notice d-link sells a couple of antennas but it doesn't seem to increase range even though it is advertised as doing so. The one antenna is a omni-directional with a gain of 4dBi.
DI-514
Is 7dBi the best gain that can be acheived with this type of antenna?
Would I see any improvement in gains by adding a 7dBi antenna?