Technical explanation on iPhone 4 Antenna issue

[crazyitalian198]

Jeez....why justify this talk anymore?



It happens with all 3G capable iPhone devices running iOS 4 depending on your location. Thus, it must be a firmware issue.



Do we really think Apple....a leader in innovative products....doesn't have 15 engineers figuring out the antenna system!


Give me a break.















of that kit kat bar...

 

[GamecockMac]

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.

Wow, I was unaware that Apple's iPhone was the first and only cellphone to use curves in its case design, and that all others have been composed of RF-friendly flat surfaces only. Gee, you learn something new everyday.

Tell us, how long is the degree program in electrical engineering at DeVry these days?

 

[EstrlM3]

Bumper installed and still seeing drops.

Phone without bumper lost zero bars in a different area. Seems signal-related to me.

my 2g iPhone (running ios3) drops 2-3 bars if i cup it in my left hand for 10-15 seconds.

there is no "new" issue with the ip4 design. it drops bars but not calls for me.

 

[EEiPhoneFail]

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.

Since you appear to be an authority on this topic, would you please elaborate on my digression from fact?

 

[GamecockMac]

Since you appear to be an authority on this topic, would you please elaborate on my digression from fact?

Since you appear to be an obvious troll (based on your chosen username) would you please just **** and GTFO?

 

[kolax]

I agree - they repositioned the antennas to save internal space to make the device slimmer.

The very least they could have done was had thin rubber go around the edge (glued on), so it doesn't disturb the design or thinness but prevents your hands touching the antenna.

 

[whsbuss]

All cell phones suffer dropped calls..... its the nature of cellular technology. I'm leaning towards a poor design concept on Apple's part. If were seeing signal degradation when were just sitting around touching the iPhone, what's going to happen when were in our cars switching between towers? That could be a real problem.

 

[King Luis]

correct me if i'm wrong here, but basically your saying that if you touch an antenna (skin to metal) it will disturb the signal and cause reception issues?

if that is true, why does my garage radio get better reception when i grab the antenna with my hand?
why does my car key work better when i'm touching the metal part to my skin?

touching an antenna does nothing with reception. if anything it will enhance it as it will use your body as an antenna also.

not saying your completely wrong, i'm saying theres more into this issue then it seems....like why only the left corner? why not the whole phone?

EEiPhoneFail name also seems like a troll. mods, get to work.

 

[Rodimus Prime]

Sure they would. You keep right on believing that fantasy, Sparky.

And yet history has shown that all have had signal problems when compared to other phones on the same network. 4 years in a row.

Apple Macbook Pro have much poor wifi than the Macbook and other laptops due to they choose the form over the function there.

Wow, I was unaware that Apple's iPhone was the first and only cellphone to use curves in its case design, and that all others have been composed of RF-friendly flat surfaces only. Gee, you learn something new everyday.

Tell us, how long is the degree program in electrical engineering at DeVry these days?

Yet if you look at other phones and find the antenas in them they will lot of the times be long and straight. The surface of the phone may be curved but the antenna would be flat. under it. They would use material that would allow RF to pass threw it very easily (plastic being a good one)

But as I said Apple has had a long history of choosing form over function and they would be very willing to sacrifice performance for looks. They have a history of it.

 

[admanimal]

This explanation does not address the primary source of the problem.

The majority of people aren't experiencing (noticeable) signal loss from touching just anywhere on the antennas. We can cover virtually the entire metal border of the phone with our hands and not see any difference. However, if there is even a light touch of a finger over the bottom left black rubber gap between the two antennas, signal loss is dramatic and almost instantaneous. This clearly tells us that it isn't a simple case of interference with the antennas due to touching it, but something specific about "connecting" the two distinct antennas in some way.

 

[whsbuss]

correct me if i'm wrong here, but basically your saying that if you touch an antenna (skin to metal) it will disturb the signal and cause reception issues?

if that is true, why does my garage radio get better reception when i grab the antenna with my hand?
why does my car key work better when i'm touching the metal part to my skin?

touching an antenna does nothing with reception. if anything it will enhance it as it will use your body as an antenna also.

EEiPhoneFail name also seems like a troll. mods, get to work.

Don't shoot the messenger..... what band is your garage radio working on? Analog or Digital? You should google cellular technology and see how it really works before trashing a theory.

 

[Rodimus Prime]

correct me if i'm wrong here, but basically your saying that if you touch an antenna (skin to metal) it will disturb the signal and cause reception issues?

if that is true, why does my garage radio get better reception when i grab the antenna with my hand?
why does my car key work better when i'm touching the metal part to my skin?

touching an antenna does nothing with reception. if anything it will enhance it as it will use your body as an antenna also.

EEiPhoneFail name also seems like a troll. mods, get to work.

No he is still right. The human body really screws with RF signals due to the large amount of water we have in it and it puts huge uncontrolled variables in the equation.
Also a receiver can get away with things like that lot easier and some times having the human body on it improves a receiver but it screws with a transmitter.

The reciever explaining kills your radio in your garage.
As for killing off your car one again you are doing little things to help control it so you are adding a variable you can control to it.


I also can point out to explain that on some thing touching it will screw with the receiving and transiting. It depends on orientation and other things but it is a huge uncontrolled variable that should not be in the design.

 

[Macficionado]

LOL.

It is ludicrous to judge EEiPhoneFail because he chose iPhoneFail as his username. I think he's providing very valuable input from an engineering perspective as to what could be going wrong.

To those that say that Apple engineers would have necessarily been able to see this beforehand, the issue may have to do with an inherent tradeoff between functionality, aesthetics, and design cost. Did they measure the reliability of the iPhone under every conceivable signal strength? Probably not; the area close to Apple has one of the best cell phone receptions in the nation.

I'm not saying that I agree that it's 100% sure a design flaw. All I'm saying is that the antenna may or may not be better than the previous antenna. At this point, all we can do is wait until we have access to more controlled experiments. Meanwhile, I'll take EEiPhoneFail's fact-based discussion before "hehe EEiPhoneFail must be wrong because he has a mean username" any day.

By the way, I have the 'bug'.

 

[snverhallen]

Just out of respect for the OP, don't bash him down just because of his name. It genuinely seems that he's trying to provide insight on this situation so don't go telling people to **** and GTFO.

 

[mcorf]

I have not been able to reproduce any of this and I have tried with both mine and my nephews phone. 5 bars all the time in NE Ohio, and no bumpers. Guess we are lucky.

 

[EEiPhoneFail]

correct me if i'm wrong here, but basically your saying that if you touch an antenna (skin to metal) it will disturb the signal and cause reception issues?

if that is true, why does my garage radio get better reception when i grab the antenna with my hand?
why does my car key work better when i'm touching the metal part to my skin?

touching an antenna does nothing with reception. if anything it will enhance it as it will use your body as an antenna also.

not saying your completely wrong, i'm saying theres more into this issue then it seems....like why only the left corner? why not the whole phone?

EEiPhoneFail name also seems like a troll. mods, get to work.

Your garage radio gets better reception (keyword here reception) because it is a receiever (keyword here receiver) only. When you make contact with the antenna in this particular application your body becomes a bigger antenna for the radio.

As for your car transmitter it has the same effect. You are effectively increasing the size of the antenna with your body acting as a pseudo antenna.

Both applications above are PASSIVE half-duplex (one way single communication) examples. They do not apply to the sophisticated design of an ACTIVE full-duplex antenna, which is a very high speed switching (800MHz -1900MHz) transceiver that is acting as a transmitter and receiver at the same time. Which is very sensitive to impedance fluctuations.

 

[whsbuss]

Your garage radio gets better reception (keyword here reception) because it is a receiever (keyword here receiver) only. When you make contact with the antenna in this particular application your body becomes a bigger antenna for the radio.

As for your car transmitter it has the same effect. You are effectively increasing the size of the antenna with your body acting as a pseudo antenna.

Both applications above are PASSIVE half-duplex (one way single communication) examples. They do not apply to the sophisticated design of an ACTIVE full-duplex antenna, which is a very high speed switching (800MHz -1900MHz) transceiver that is acting as a transmitter and receiver at the same time. Which is very sensitive to impedance fluctuations.

Yep you are correct. Its sad that so many experiencing this problem are unwilling to admit it. Its always easy to ignore viable theories. As I said before google cellular technology so you can understand how it works.

 

[CubeHacker]

You guys do realize that you CANNOT go by the number of bars to see if this problem exists or not. The only sure way to see if this problem happens with your phone is to look at the signal strength in dB - which AFAIK cannot be currently accessed on the iPhone4.

Reason I bring this up is because in my house on my iPhone 3G I get a signal strength of -51dB, which equates to full bars. If I had an iPhone 4 starting out at -51dB and covered the antenna, my signal might drop to -70dB, which would still equate to full bars. Thus, I would assume that my phone is problem free.
But if I start out at -70dB or less (like some people do in areas of weaker reception), and I cover the antenna, it might bring me to -90db or less, enough to watch the bars drop, and possibly even drop the call.

This is why you CANNOT use bars to determine if this issue exists in your phone.


And the OP is correct about why this issue exists. A simply way Apple could have addressed it is by applying a thin coating of some kind of clear acrylic to the metal band so that direct contact with the body would never occur. You would still "cover" parts of the antenna this way, but your skin would never actually touch the metal, thus attenuating the signal.

 

[ballen420]

Thanks for the info OP. This gives me some insight as to why I had the issue on the road earlier but can't replicate it here at my desk where a cell phone tower is across the street.

Amazing how many DB's are on this site.

 

[richard371]

I really don't understand how it can be a batch of iphones with the problem. It is clearly a design issue and makes sense based on how antennas work. Unless some of them have a clear coating on the metal band etc, I do not see how there can be a diff. Sometimes I cannot get mine to drop a bar at all doing the tests and other times it will drop several bars etc depending on where I am. I think there are way to many variables here and it is to widespread to be a bad batch.

I think swapping the phone out right now would be a waste of time. I am using a bumper anyway even if there is no issue. I will wait until Apple confirms the issue and has a resoltion.

Have there been side by side tests where some do and some don't? I read one guy said all 10 in the Apple store display did this. This still may be flawed depending on how it is connected to the tower.

 

[EEiPhoneFail]

Thanks for the info OP. This gives me some insight as to why I had the issue on the road earlier but can't replicate it here at my desk where a cell phone tower is across the street.

Amazing how many DB's are on this site.

No problem.

I want to reiterate, that I am by no means an epxert on this topic. But the very nature of this issue is not significantly complicated, relevant to RF theory.

Like others speculated in previous posts, it is most likely a case of form over function. I am sure there was backlash from the engineering department, but as most people in industry know, engineering is usually of the minority opinion when it comes to revenue.

 

[ScubaCinci]

According to this, it's a software issue although the OP's explanation sounds plausible. I have tried to replicate this degradation in signal and have not been able to. No matter where I am, it doesn't seem to occur. I'm not too upset by that

 

[roland.g]

This is why just like a minimum number of posts for an avatar, there should at least be a minimum of posts required for thread creation.

Maybe that way RF'dNdaHead wouldn't have 8 posts total, all in his own thread.

"Join Date: Jun 24, 2010" - Oh yeah, that's todayfail.

 

[admanimal]

No problem.

I want to reiterate, that I am by no means an epxert on this topic. But the very nature of this issue is not significantly complicated, relevant to RF theory.

Like others speculated in previous posts, it is most likely a case of form over function. I am sure there was backlash from the engineering department, but as most people in industry know, engineering is usually of the minority opinion when it comes to revenue.

As I said before, your explanation still doesn't address why it only happens when people touch the gap between the two antennas. You can wrap your hands all over the rest of the border with no effect but the signal loss is dramatic, reliable, and almost immediate if you touch the right spot, which again strongly suggests that it has more to do with some interaction that your hand is causing between the two antennas than anything with normal interference from touching a single antenna.

 

[CubeHacker]

It sounds pretty simple - you are bridging the gap between the two bands, causing your body to act as an "antenna" - something its not very good at. If you touch the band with only one finger but don't touch the other end, the signal should remain mostly unchanged.