Remembering Antennagate

Posted on Jul 31, 2017
Remember Antennagate? In 2010, with the release of the revolutionary new iPhone 4 came problems with the new external antenna that wrapped around the sides. There was a gap between the metal pieces of the antenna that when bridged by the user’s hand would detune the antennas and degrade performance. Sometimes the degradation was so bad, calls would be dropped.

 

 

iPhone 4

iPhone 4 had antenna gaps on the side that could be bridged by the user’s hand.

iPhone 5

iPhone 5 used the only the top and bottom of the external metal for the cellular antennas.

This problem exists to some degree in all phones with or without internal or external antennas. Just putting the phone up near your head will de-tune all antennas somewhat. If you are actually putting your hand on the antenna as in the case of the iPhone 4, it will likely de-tune it even more. Stuart Sanders, Principal RF Engineer at Sanders RF Consulting LLC, was quoted in an article in WirelessWeek.com where he discussed public perception versus reality regarding this topic. He argued that were it not for the high profile of the device and the promotions about the external antenna, the issue might have gone unnoticed. He said, “If I had to put my hand in a big mitten and then hold the phone six inches from my head in order to make a call, then it would be a problem.”

The actual cause of the “problem” was the the iPhone 4 used the external metal band that wrapped around the edges of the phone as the antennas, and it was broken by a gap into two different sections. One section was used for the GSM cellular receive/transmit, the other for WiFi, Bluetooth, and GPS. Connecting the two antennas by gripping them both at the same time with your hand caused capacitive coupling which de-tuned both antennas. A class-action lawsuit was brought against Apple over “Antennagate,” and buyers of the iPhone 4 were given the option of a free rubber bumper that would protect the antenna from a user’s hand or a check for $15.

The iPhone 5 antenna was significantly modified– the cellular antennas were split for GSM and the new CDMA cellular radio, and only the strips of the metal running across the top and bottom of the phone were used for the cell antennas, making them less susceptible to detuning. The Bluetooth, Wifi, and GPS antennas were located inside the phone, radiating out through the glass at the top and bottom of the phone. This eliminated the need for a bumper.
iPhone 6

iPhone 6 extended gaps across the back of the phone through which the internal antennas’ signals radiate.

iPhone 7

iPhone 7 moved the antenna gap up above the camera and almost down to the connector.

On the iPhone 6 model, there appear to be two antenna gaps/loops that run across the back, top, and bottom of the phone. So it seems Apple moved the antennas inside the phone, and now these new gaps are used to let the RF signals radiate out of the phone. Testing indicates that if you are left-handed, your cell performance will be worse than if you are right-handed. This implies that cellular antennas in the iPhone 6 radiate more from one side of the phone or are detuned more when one side of the phone is touched. These tests also indicate that Apple’s antenna performance is not as good as some of its competitors.

For iPhone 7, the gaps across the back of the phone remain, but the loops were removed, so that now there is only one gap up above the camera and down by the connector, with a mostly smooth metal back. This is apparently Apple’s way of trying to appease those that were unhappy with the aesthetics the iPhone 6 being marred by the plastic gaps. And since iPhone 4, there have been no Antennagate-type issues, and no associated bumpers released. So it appears Apple stayed with the current idea of gaps across the back in the iPhone 7 but moved the internal antennas even further away from spots where the user’s hand will bridge or block the gaps.

It will be interesting to see how iPhone 8, or whatever the next generation of iPhones is called, addresses this antenna issue. This new model is rumored to have a screen that goes flush to the edges, which may impact an antenna that runs along the edges of the phone. Apple also has applied for a patent for a new composite metal material that looks and feels like anodized metal, yet allows RF signals to pass through. If this material actually works, the Apple iPhone 8 may be the first phone since the plastic-backed iPhone 3 with no gaps.

If your company is having antenna design problems, please contact us at Sanders RF Consulting.