I have an D-link ADSL 2640T and would like to know if you can get a booster aerial or something like that at Pan Thip to increase its range

Probably you can.

In Pattaya's TukCom center are at least 3 shops stocking several models of high gain antenna's, along with the little pigtail cable allowing you to hook them up to different brands of access points.

So I'd guess Pantip will have them as well!

Don't get fooled into buying wifi power boosters, unless you live somewhere out in the boonies. They do work great, but as side effect they will render pretty much all other wifi connections in the nearby area useless. Your neighbours won't like you then, unless you have a blistering fast connection and you are not securing your wifi

that wireless is a dark art

beware of buying a cheap antenna advertised as 5 db gain - you might be lucky to get 2

do you need omni directional or directional

have a look at freeantenneas.com or http://www.usbwifi.orcon.net.nz/ and see what you can knok up out of household goods

are you trying to hit an access point at a distance or extend the range of your own access point ?

2.4 GHz cordless phones are a pain as they hop all over the spectrum.

If you can set up your router somewhere at one end of your living area, I'd do that and get a directional antenna to boost the signal.

Otherwise, a 8dbi or 10dbi omni will do. There are different qualities with the better ones pretty expensive , and keep in mind that the cable that connects the antenna to the router incurs a signal loss - so make sure you get a cable that's good, and short (the shorter the cable, the less loss).

WiFi range all depends on what's inbetween you and the router. If you have free line of sight, you can get the WiFi signal 100m away, and 1km away with a directional antenna. If there's some heavy concrete walls in the way, it might not even reach two rooms. Therefore, strategic placement and experimenting with the antenna / router location is of paramount importance.

I have seen people put the WiFi router under the counter in a drawer. I guess to have it out of the way. The problem is, it won't provide you with a good signal that way. Mount it somewhere high up and where there's not a lot of stuff between it and your computers... the built-in antennas work best if they are vertical.

Edit: I almost forgot, get Netstumbler (Or Kismac on the Mac) so you can run it on your laptop and measure the signal anywhere in the house. It shows you a nice signal/noise ratio graph. It's the best way to experiment with different locations for the router. The Windows (or Mac) built-in signal strength display is extremely inaccurate to the point where it's useless for measuring one location vs the other. You can get 5 bars on a crap signal, you could get 1 bar on a pretty stable signal - it's not good enough.

BTW DLink is usually pretty good when it comes to signal strength. You might be able to increase the power output on that router via the web interface. I know my DLink routers can do that. Makes only a small difference, but why not.

I have the ASUS WL-330gE access point

it's a small pocket size device which can function as a WIFI repeater.

in the repeater mode it just boosts the weak wifi and extends the coverage.

a great alternative to extarnal antenna