Although there's never been any question that there's something going on with the iPhone 4's fancy new antenna system, we really haven't seen any rigorous testing confirming that the issue is real, severe, and affects every phone. That just changed: Consumer Reports tested three iPhone 4s and several other AT&T phones in their RF isolation chamber that simulates varying levels of signal from every carrier, and found that the iPhone 4 was the only handset to suffer signal-loss issues. What's more, CR directly says that its findings call Apple's explanation of a miscalculated signal meter into question since the tests "indicate that AT&T's network might not be the primary suspect." CR found that simply putting duct tape over the bottom-left corner is enough to alleviate the issue -- we're guessing that's Jony Ive's worst nightmare -- and says that while the iPhone 4 has the "sharpest display and best video camera" of any phone it's tested, it simply can't recommend the device until Apple comes up with a permanent and free fix to the antenna problem. Ouch.
Of course, we couldn't sit around waiting for someone else to test the iPhone 4 in a more controlled way, so we actually asked our good friend Erica Sadun from TUAW to write us a bespoke signal strength app for iOS 4. Obviously we couldn't submit it to the App Store, but we've been running it on all of our phones here at Engadget and we can independently confirm Consumer Reports' finding that there's a serious signal attenuation issue with the iPhone 4's antenna -- every phone we've tested displays dropped signal when held with the bottom left corner covered. Now, what we don't know is whether that signal attenuation consistently affects call quality and data rates, which we suspect is more directly related to the network in the area; some of our iPhone 4s drop calls and experience low data rates with alarming frequency, while others -- like our review unit -- have almost never dropped a call and have had no data problems. However, now that we've confirmed and clarified that the antenna issue affects every iPhone 4, we can take on the next step, which is sorting out exactly when and where the issue is most severe. Either that, or Apple can do something to actually fix the issue -- we'll just have to wait and see. For now, check our app in action after the break.
Update: To clarify, "here at Engadget" is a virtual location -- our iPhone 4s are actually located across the country in San Francisco, Chicago, and New York, and we saw the app respond that way regardless of location. Dropped calls and other effects weren't as consistent, however, and we're still testing to sort out when the effects of the antenna issue are the most severe.