What to get for Wi-Fi extension?

So I heard about Wi-Fi range extenders but unfortunately I read that it's slows the Internet speed, so I bought a powerline instead. I found out when I setup the powerline that the connection goes only to the device the Ethernet is connected to. Does anyone know a power line that even when you connect the adapter to your computer, I could receive Wi-Fi to different devices wirelessly like an iPhone

Apple sells them. Look on their website.

Wi-Fi extenders should not slow the internet speed.

I use devices similar to:

http://www.tp-link.us/...WPA4220KIT

Typically I get less than 5% variation in speed. Normally the closer Wi-Fi source gives the best speed with this type of device. I use different wireless network names (SSID) so I know which network I'm using.