Apple’s response to those experiencing iPhone 4 reception problems is to tell them to not hold the device so that your fingers cover that thin black band on the lower left of the device’s outside edge.
The reason this causes a reception problem is that this thin black band (and a similar one on the other side of the device) is actually the insulator that separates two antennas, one for the UHF part of AT&T’s voice band and the other the microwave 3G, WiFi and GPS signals.
When you touch this thin black band, you provide an electrical pathway between these two antennas. How much of a pathway you create depends on your personal physiology and the conductivity of your hands. Your hands can change these characteristics when they’re wet, and especially if they’re sweaty, since perspiration contains salt, which aids in conduction.
Yes, it’s part of the basic design of the iPhone 4’s antenna that you can effect its reception in this way. That doesn’t necessarily mean that it’s a bad design.
In most wireless devices these days, the antenna is printed on the main circuit board, or one that’s situated next to it. It looks like a copper zig-zag design, and it’s usually under the keyboard or the battery. Apple’s engineers took an innovative approach to creating antennas with good access to free space, appropriate physical and electrical length for the frequencies required, and a robust physical design.
From an engineering viewpoint, the iPhone 4 has a seriously good antenna design. From a usability viewpoint, not so much.
To read the original eWeek article, click here: Apple iPhone 4 Reception Problems a Lesson in Antenna Design