Starting with iPhone 12, Apple added this rounded cutout on the side of every model. But they didn’t explain what it was or why it existed. Many assumed it would be for the Apple Pencil. Since it looked similar to a cutout included on the iPad that allows the second generation Apple Pencil to magnetically attach and charge. But the iPhone doesn’t support Apple Pencil. So why did Apple add this cutout to iPhone?
Well, it turned out to be one of several changes Apple had to make to accommodate 5G cellular connectivity on their phones. Since the antenna system used on iPhones since the 5 was designed for 4G or LTE cellular networks. The transition to 5G would require an additional antenna system. So the problem Apple faced was deciding where that antenna would go. Since placing it in the wrong location could cause reception issues or dropped calls.
Problems with iPhone 4
That’s what happened with the iPhone 4 in 2010. When Apple created a new antenna system that was integrated into the device’s flat edges. Allowing for a full glass back instead of plastic like previous models. But the antenna had some shortcomings, and customers experienced more dropped calls and
fewer network bars than ever before. That’s because plastic allows radio signals to pass through much easier than glass or metal.
Apple’s solution to 5G is Plastic
Apple eventually improved their antenna system with subsequent models, but adding 5G to the iPhone 12 was particularly challenging. Since Apple would have to reintroduce a design element not seen on a flagship iPhone since the 3GS; plastic. The original iPhone had a black plastic section on the back to allow for cellular signals to easily pass through. While the 3G and 3GS had a completely plastic back. The new antenna system on iPhone 4 allowed Apple to ditch the plastic and make the back panel 100% glass. And we’ve seen variations of this form factor until today. But 5G forced Apple to added a plastic section, like on the original iPhone.
Luckily, it didn’t have to be as large. So they were able to create a cutout on the side of iPhone 12 to fit a plastic window that would allow 5G signals to pass through. If Apple eventually reengineers their antenna system, we may see this cutout disappear. But for now it’s become an integral part of the iPhone’s design.