As noted by AppleInsider, the plastic iPhone 5c requires case makers to design radio-friendly transparent windows at the top of bottom of the device, indicating that the radio technology design inside of the iPhone 5c is similar in placement to that found the iPhone 5, which integrated cellular and other antennas in the upper and lower sections of the device.
Meanwhile, the metal and aluminum iPhone 5s now requires case makers to compensate for the new Touch ID fingerprint sensor, with the restricted area for cases surrounding the home button slightly larger than that of the iPhone 5c and the previous generation. iPhone 5. The document also notes that no metal should come in contact with the iPhone 5s chassis, citing unwanted interruption with the device’s antennas and signal degradation.
Apple will begin selling the iPhone 5s and lower-cost iPhone 5c this Friday, September 20. The company began taking pre-orders for the iPhone 5c in 10 countries on September 13, with online orders for the iPhone 5s set to begin early in the morning local time on Friday prior to the in-store availability later in the morning.