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Technical explanation on iPhone 4 Antenna issue

E

EEiPhoneFail

macrumors newbie
Original poster
Jun 24, 2010
11
0
The reason you are dropping calls is due to the fact when you physically make contact with the antenna (any antenna) you disturb or change it's impedance properties. Fluctuating the impedance on an antenna causes signal propagation issues.

An antenna is essentially analogous to a tuning fork, and when it is vibrating/reverberating any changes to the vibrations (i.e. an impedance fluctuation) will compromise/distort the propagated signal. If this continues long enough the tower you are communicating with will no longer know where you are and say goodbye.

There is a reason this has never been done before (exposed antenna) it's a very bad design from an RF perspective. It's RF 101, and if you do a little research and take a look at other phones, you will notice that ALL cell phone antennas are galvanically isolated to some extent.

It is not a firmware issue, it is an inherent design issue, line up and get your rubber bumper.
 
Obviously apple has never had to design anything with an antenna before... Nope, can't think of a single thing...
 
EEiPhoneFail said:
The reason you are dropping calls is due to the fact when you physically make contact with the antenna (any antenna) you disturb or change it's impedance properties. Fluctuating the impedance on an antenna causes signal propagation issues.

An antenna is essentially analogous to a tuning fork, and when it is vibrating/reverberating any changes to the vibrations (i.e. an impedance fluctuation) will compromise/distort the propagated signal. If this continues long enough the tower you are communicating with will no longer know where you are and say goodbye.

There is a reason this has never been done before (exposed antenna) it's a very bad design from an RF perspective. It's RF 101, and if you do a little research and take a look at other phones, you will notice that ALL cell phone antennas are galvanically isolated to some extent.

It is not a firmware issue, it is an inherent design issue, line up and get your rubber bumper.
Click to expand...

Ignore.
Basher.
 
Bumper installed and still seeing drops.

Phone without bumper lost zero bars in a different area. Seems signal-related to me.
 
Ya, I'm pretty sure a company like Apple would've had some of their designer and engineers take RF 101. I'm sure they probably even graduate RF University.

My husband has his iPhone 4 already, and I tried to duplicate the issue, and it his phone worked flawlessly. So I'm gonna wait and see what Apple says, but I have a feeling it's probably software related.

If it's hardware related, then no big deal. I'm sure Apple would replace the phone, so who cares?
 
SiskoKid said:
Ya, I'm pretty sure a company like Apple would've had some of their designer and engineers take RF 101. I'm sure they probably even graduate RF University.

My husband has his iPhone 4 already, and I tried to duplicate the issue, and it his phone worked flawlessly. So I'm gonna wait and see what Apple says, but I have a feeling it's probably software related.

If it's hardware related, then no big deal. I'm sure Apple would replace the phone, so who cares?
Click to expand...

If you are closer to a tower than say someone else, then the antenna may be superceded by internal coupling, that is the signal does not need the antenna to communicate, and it may bypass it entirely.

Also, location information is sent out arbitrarily in packets at random intervals, so it is possible to attempt to replicate this anomaly, and not have the same outcome due to the absence of communication in general.

A new phone will not rectify the issue, it's an inherent design issue. So a new design would be required to resolve this entirely. Although they can modify/tweak the transceiver firmware to better cope with the impedance fluctuations.
 
EEiPhoneFail said:
A new phone will not rectify the issue, it's an inherent design issue. So a new design would be required to resolve this entirely. Although they can modify/tweak the transceiver firmware to better cope with the impedance fluctuations.
Click to expand...


So you're saying there is no way to fix it with software? So this is a fail design, crud, how're they going to fix this?
 
The defining factor with this issue will heavily rely on demographics. If you live in a major city, with a relatively new tower infrastructure, the effects of the antenna may be negligible enough as to not compromise communication. But if you are living in a smaller demograph, with older infrastructure, this issue may be significant enough to cause periodic (if not complete) disruption in communication.

For the record I am not trying to bash the iPhone, I own one. I am just dumbfounded as to how they could allow an antenna design such as this to pass a design review. I was anxiously anticipating an iPhone 4 upgrade myself, but this recent influx of issues has put me on the sideline.

I hope they are able to effectively resolve this issue in a timely fashion.
 
i.phone4 said:
So you're saying there is no way to fix it with software? So this is a fail design, crud, how're they going to fix this?
Click to expand...

Yes, someone named EEiPhoneFAIL (note the Fail), is an expert on the iPhone design and RF signals.

Give me a break.
 
I live in a relatively rural area and my iPhone 4 is behaving just like my 3GS. Not making any inferences, but just wanted to add another data point for folks to chew on.
 
SiskoKid said:
Yes, someone named EEiPhoneFAIL (note the Fail), is an expert on the iPhone design and RF signals.

Give me a break.
Click to expand...

I am by no means an expert on the iPhone design, or RF for that matter. But I am an electrical engineer, who has direct experience in antenna design and testing.
 
GNice said:
I live in a relatively rural area and my iPhone 4 is behaving just like my 3GS. Not making any inferences, but just wanted to add another data point for folks to chew on.
Click to expand...

Ya, my husband's iPhone 4 and 2 coworkers (one an IT guy who we tried to replicate the issue here at work today and didn't come up) all have perfect iPhones.

We do live in SF, but my reception on 3GS on AT&T is horrible in this city. And all their iPhone 4s work much better. Even having a finger over the groove.

So I don't think someone named iPhoneFail is that much of an authority on this issue.

I understand SOME people are having this problem, but I have no doubt it'll be fixed. It's too much of an oversight of Apple to have such a different design and not test it. No one's that stupid.
 
no reception issues here either... maybe if you people would calm down and your hands weren't so sweaty you wouldn't disturb the antenna :p
 
EEiPhoneFail said:
I am by no means an expert on the iPhone design, or RF for that matter. But I am an electrical engineer, who has direct experience in antenna design and testing.
Click to expand...

And I'm sure Apple didn't bother to hire a single person with your background to assist in the design and testing of the iPhone 4.

Jealous much? :rolleyes:
 
EEiPhoneFail said:
The reason you are dropping calls is due to the fact when you physically make contact with the antenna (any antenna) you disturb or change it's impedance properties. Fluctuating the impedance on an antenna causes signal propagation issues.

An antenna is essentially analogous to a tuning fork, and when it is vibrating/reverberating any changes to the vibrations (i.e. an impedance fluctuation) will compromise/distort the propagated signal. If this continues long enough the tower you are communicating with will no longer know where you are and say goodbye.

There is a reason this has never been done before (exposed antenna) it's a very bad design from an RF perspective. It's RF 101, and if you do a little research and take a look at other phones, you will notice that ALL cell phone antennas are galvanically isolated to some extent.

It is not a firmware issue, it is an inherent design issue, line up and get your rubber bumper.
Click to expand...

That was the LEAST TECHNICAL explanation, ever.
 
This is actually what I (and many others) have been thinking. The people bashing should remove their heads from Steve's a$$ long enough to listen to logic.

In fact, I did my own test today and found the following:
1st floor Den: I can touch & bridge the sections with little or no noticeable drop in signal (sometimes drops from 5 to 4 bars but mostly stays at 5). This makes it seem like I'm not having this issue, right? Wrong.

Basement office: This is a more problematic spot in terms of coverage. With my 3GS I would get 4 bars regularly but sometimes it would reach up into that 5th bar. I tried the "touch test" down there and I can reproduce the video results exactly. I go from 5 bars to none, simply by bridging the metal sections.

To me this provides some evidence to support (but I'll agree doesn't inconclusively prove) that it's related to normal signal strength from a given location vs degraded signal due to interference caused by bridging the sections.
 
I am having the issue on my iPhone 4 here in Denver. When holding the iPhone in my left hand my signal strength goes from 4 bars to dropped call in about 15 seconds. After testing further I find that the join point in the bottom left hand side of the iPhone is the point of failure when skin closes the gap. Holding the phone in my right hand I get a loss of 1-2 bars but the call doesn't drop. I can re-create this every time with identical results.

At lunch I was out around town and found that if you are close to a cell tower the signal strength is so good that the calls don't get dropped, and if your really close no bars are lost. So the issue gets much worse the further you are away from a tower.
 
GamecockMac said:
And I'm sure Apple didn't bother to hire a single person with your background to assist in the design and testing of the iPhone 4.

Jealous much? :rolleyes:
Click to expand...

But apple also has a history of choosing form over funition in its designs. I would not put it past them to do something like this.

They would rather it look pretty than function well. The iPhone 2g. 3G and 3GS all have been shown to have a crappy antenna design compared to other phones. They choose to make the phone look pretty.
 
SiskoKid said:
Ya, my husband's iPhone 4 and 2 coworkers (one an IT guy who we tried to replicate the issue here at work today and didn't come up) all have perfect iPhones.

We do live in SF, but my reception on 3GS on AT&T is horrible in this city. And all their iPhone 4s work much better. Even having a finger over the groove.

So I don't think someone named iPhoneFail is that much of an authority on this issue.

I understand SOME people are having this problem, but I have no doubt it'll be fixed. It's too much of an oversight of Apple to have such a different design and not test it. No one's that stupid.
Click to expand...

GamecockMac said:
And I'm sure Apple didn't bother to hire a single person with your background to assist in the design and testing of the iPhone 4.

Jealous much? :rolleyes:
Click to expand...

The antenna design is not a matter of opinion, it's a poor RF design. Numerous seasoned RF engineers have commented on this in various articles. I am by no means the lone stance on this topic.

Like I said before, numerous factors will influence the performance of communication with any phone. And it may become crtitical or non critical. The bottom line is that this IS a poor antenna design, and was implemented to save internal space.

If you believe Apple RF engineers are so competent. Do some research on the previous iteration's of the iPhone, and you will see why they re-designed the iPhone 4 to have flat surfaces. It is not cosmetically driven, it is due to the fact the curved surfaces (think stealth and reflection of RF energy) are very poor surfaces for coherent signal propagation, curved surfaces induce incoherence/wave collision and poor reception/transmission. Apple screwed up in the RF arena initially, and they are screwing up again.

They didn't put a gas tank bladder in the Ford Pinto because they saved $1.29 a car, but that didn't stop the numerous rear end collisions and subsequent fires and deaths.
 
Rodimus Prime said:
But apple also has a history of choosing form over funition in its designs. I would not put it past them to do something like this.

They would rather it look pretty than function well. The iPhone 2g. 3G and 3GS all have been shown to have a crappy antenna design compared to other phones. They choose to make the phone look pretty.
Click to expand...

Sure they would. You keep right on believing that fantasy, Sparky. :rolleyes:
 
OP is off slightly, but underlying principle is the same. The antenna will have massive interference from another sourc3e touching it (ie: your sweaty, greasy hands).

Whether apple took this into account of not is another issue, but I imagine the engineer that brought that up had to go to the end of the lunch line for lowering morale.
 
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