How does the iPhone 4 antenna system actually work, and what's wrong with it?

[Sedrick]

What? This doesn't explain or help me with what I asked or make much sense. Please fix your grammar or elaborate some more please!

Sorry, had the wrong word in there.

Here you go:

"It's my understanding that that's why they went with a glass back instead of something more reasonable."

 

[QuarterSwede]

The "real" question, in my opinion, is how did Apple miss something that took me and lots of others minutes to notice? What kind of culture exists at Apple that would totally miss a problem this glaring?

My guess is that because Apple has an at&t cell tower in their backyard and because they are so secretive they never noticed it when testing it off campus since all prototype iP4's had 3GS looking cases.

 

[imagineadam]

What happens when you change the back to plastic or metal like some are doing??

That's what I'm wondering too? I'm guessing that blackstrip on the backplate isn't that high tech if these knockoff companies are selling those replacement ones on eBay like hotcakes! Or is it?! Does anybody know exactly what that blackstrip does?? It does connect to the antenna system according to the pictures on this post. What does it do??!

 

[imagineadam]

FCC points out "main 3G antenna"

Go here: https://gullfoss2.fcc.gov/oetcf/eas...me=N&application_id=573413&fcc_id='BCG-E2380A

Then click on 11d SAR test setup second to last link.
Here it shows correctly the main antenna for the iPhone4. Case solved. The steel band must be just boosting the reception. The black panel on the back is just a RF window. So you were mostly right Josh hawn!

You make a good point about power factor matching with the added resistance, but I don't really think it would matter all that much because actual power factor correction involves complex impedances and there aren't any capacitors or inductors in this stainless steel band that I can see.

Another problem I see with it is: Why does the problem only occur at the bottom left seam and not on the top seam? I did some more investigating to try to figure it out, and even thought of a way to fix the problem:

Photo courtesy of iFixIt.com

See that brass screw mounting point on the right? That's what brings the larger stainless steel band into contact with the antenna system. Interestingly enough, it's located right where the signal attenuation problems occur! (This is the back of the iPhone, so it's located on the lower right rather than lower left). When you bridge that seam whether it be with your finger or any conductive material, it shorts out the antenna! This is a small enough distance that it has an effect. This would explain why the signal attenuation does not occur at the seam at the top of the iPhone 4, near the headphone jack: because it's too far from this location for the current to be grounded to the Wi-Fi/Bluetooth/GPS antenna. That extra length makes the resistance too high for there to be a significant short across to the other part of the stainless steel band.

 

[gslrider]

Sorry, had the wrong word in there.

Here you go:

"It's my understanding that that's why they went with a glass back instead of something more reasonable."

lol. I understood you the first time. ;-) People make typos on forums all the time, even text messages and emails. It happens when your brain is faster than your fingers. But I've learned to read "online" messages. It's not that hard to realize you meant "live" instead of "life". Guess some people are just anal about their grammer, as well as others, and like to point out that they have a better grasp at it than others. lol

As for the topic, supposedly, Apple rolled out their next batch of iP4's with the antenna issue fixed late last year. I received my upgrade to the iP4 in November, and I'm still having issues with wifi disconnecting, even with full wifi bars, and standing beside my router. I'm thinking it's might have to do with the iOS as well. Just like all the other issues plaguing the iPhone.