iMac internal wifi versus external adapters

[tuna]

How do the internal antennas in iMacs compare to external antennas? I'm having trouble getting a consistently fast connection with my wireless access and its very frustrating. I am using a 2006 20" iMac.

My router control panel shows my connection strength typically being around 18%, which I think is close to the edge of being a consistently reliable connection because I have other computers that get a 30% connection and work great.

I just ordered an external wifi adapter with a large, prominent antenna, and the consensus of user reviews on Newegg is that this product typically improves performance versus the wifi adapters built into their computers. Am I going to see an improvement? Or is the antenna in the iMac already huge and this isn't going to do anything for me?

Here's to hoping. I'm right on the edge. Sometimes my connection will burst up to very fast speeds, but more often it is frustratingly slow. It is not a router issue, all my other computers that have better connections always work fast.

 

[mulo]

The entire iMacs screen is basically an antenna.
If you think it's the iMac that's the issue, take a laptop cellphone, you name it, and compare signal strength when next to the iMac.

 

[tuna]

The entire iMacs screen is basically an antenna.
If you think it's the iMac that's the issue, take a laptop cellphone, you name it, and compare signal strength when next to the iMac.

Good idea. If I hold my iphone up in the air right next to the iMac, it gets about the same exact signal strength. Considering that its a freaking phone, I think there is some hope that an external antenna can improve the connection.

Which way is the iMac's antenna directional? I know that all antennas have directionality, I've seen the diagrams of antenna signal outputs. The "wand" antennas have a doughnut shaped output around them, and the flat antennas are more directional and are stronger in some directions and almost nonexistent in other directions.