Phyiscially there ain’t much difference between a Wifi iPad and a 3G iPad other than the inclusion of a black plastic RF window on top of the iPad for better antenna reception.
But the inside of a 3G iPad is amazing, 5 antennas in just a small size iPad to ensure you will get great surfing experience.
Here’s the quote from ifixit:
There are actually FIVE antennas in this iPad: Two antennas handle the cell reception — one is in the RF window on top, the other attaches to the LCD frame. A single GPS antenna is also housed in the RF window on top. Just like the iPad Wi-Fi, there are two antennas that handle Wi-Fi / Bluetooth connectivity, one in the Apple logo and another to the left of the dock connector.
* You heard that right, folks: Apple looks to be using the entire LCD frame as an antenna!
* Who would’ve thought: Apple uses the same 3G baseband processor in both the iPhone 3GS and the iPad 3G.
* The baseband processor in question is the Infineon 337S3754 PMB 8878 X-Gold IC. It was actually white-labeled on the production unit, but with enough sleuthing we were able to confirm its true identity.
* The iPad 3G has a Broadcom BCM4750UBG Single-Chip AGPS Solution, whereas the iPhone 3GS uses an Infineon Hammerhead II package. Big win for Broadcom!
* Apple did not change any major suppliers between manufacturing the pre-production unit they provided the FCC and their final production run.
Using the entire LCD frame as antenna is a superb concept as iPad is nothing but a big LCD screen. Haha!