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Hello.
First. Thanks to your post.
I have interest to NFC in the new iPhone. iPhone 6!
But I can't find any information fo that's antenna.
Where is the NFC antenna?
Please find it. :D
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Just worked this out, this is for iPhone 6, however iPhone 6 plus should be similar.
The NFC antenna is the top bezel itself, the top bezel has 2.4G(wifi and Bluetooth), cellular diversity, GPS and NFC. The main feed point for GPS, cellular and 2.4G is the screw boss under the plastic add-on antenna, with a "grounding bracket" attaching it to the bezel. The plastic antenna serves as the 5G wifi antenna.
The NFC antenna feed point is the screw boss next to the camera and sleep/wake button, with a flex cable under the camera bracket serving as signal conductor.
There is an additional feed point in the middle of the bracket, it does not connect to any wireless services, however it connects to a dynamic switch to tune the top bezel dynamically to serve different bands.
The F-shaped flex cable on the back of the board is JUST a bridging cable, not an antenna in any way.
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"The main feed point for GPS, cellular and 2.4G is the screw boss under the plastic add-on antenna, with a "grounding bracket" attaching it to the bezel. " Do you have any picture to describe this?
iPhone 6 logic board replacement guide, step 29.
Thanks mate. Do you think if this part is bad, could cause any problems with your cellular reception? I have an iPhone 6 with bad reception, replaced it and might noticed a little better reception. Other parts?
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The entire top metal band and associated flex cables are a complex antenna assembly, I'm still trying to figure out which part serves NFC.
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the copper bar in the flex. NFC needs a smaller antenna as you don't want a large dipole to send the signal out to many directions nor offer too great a distance.
Dan, you mean the small part in the top left corner in the phone?
Here's a good image of the iPhone 6 logic bd. between the fingers is the NFC antenna iPhone 6 here in the iPhone 6 Plus the antenna clip its self holds the NFC antenna iPhone 6 Plus
Well, to me the oddly shaped flex cable is just like the RF flex cable on iPhone 5 logic board. Maybe it's just a conductor, bridging the signals. The actual antenna is somewhere else.
On the logic board there are some contact pads and screw bosses that are obviously connected to the circuit, those are antenna outputs i think.
Also Apple has this patent: Communications device and method for having integrated NFC antenna and touch screen display. US 8718553 B2. Maybe it is implemented but I'm not sure. Now we can only wait for someone to leak the circuit diagram online and further analyse it then.
There is only appear to be three antennas in the iPhone 6 series: the top case and the case body for Cellar & WiFi services (I'm not sure which is for what here) and this small one internally for the NFC.
The usage of AS3923 chip is well-known by now. This chip does some adaptive-tuning, which can potentially allow the outer case to be used as a major part of the NFC antenna. I can't say if that is how it is done, but that is how I would do it.
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The case is too emissive and not directional. The specs of the chip states a 10mm antenna is needed.
I've been working on NFC/RFID since 2003 and higher frequency RF since 2007. I have learned some things about antennas. Here are a few of these things: (1) any piece of metal can be made into an antenna. (2) a small driven element can be coupled with an external piece of metal (i.e. a case) to create a larger antenna, if it is designed as such. (3) touching an antenna creates a capacitive load that changes tuning of the antenna. (4) electrically small antennas generally do not have directive gain.
Ideally, the AS3923 can modulate the source impedance to offset any variable capacitive load as a result of handling the case. Moreover, directivity isn't really a factor in the near-field.
If the iPhone only needed a single antenna then the case could have been used, but the iPhone needs a few different antenna's. We know what the case does from the iPhone 5 & 5s models which are the first models Apple used the case as the antenna for cellar services. So I doubt Apple would change directions here. Besides the teardown clearly shows the three antenna connections Cellar, WiFi & NFC). You may want to review antenna modeling as size can effect distance.
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