Why just blame the iPhone?
I'm no Apple fanboi but surely these findings affects all phones, if making a connection between your hand and the antennae, even through a plastic barrier, degrades the signal.
The so-called 'death grip' effect, in which a user's hand touching a smartphone antenna degrades its radio connections - a major issue for the iPhone 4 with its external antennae - is real and is a serious problem, according to British boffins researching the matter. Furthermore they found that plastic insulation between hand …
Why does the iPhone 4 get a signal in places where my old Motorola didn't (just a week or so before)?
The thing about the iPhone 4's antenna design is the "weak spot" is marked with other "traditional" designs there is a "weak spot" but it hasn't got a line showing you where it is!
Now the iPhone 4's design isn't perfect, the thing is a bit "slippery", especially with glass on both back and front, but I don't think raw "network coverage" is really an issue - mine seems to find a signal in places where both Nokia and Motorola handsets didn't. Yes, we're talking about the same network.
No I don't use a case with the iPhone 4, and it's just "stock" not modified or weird (or white!)
What is really impressive is the battery life (for a smartphone). Putting the antenna assembly in the phone's main structural element does make room for a bigger battery.
This is the first step of such a project.
It may be that the results don't come as a surprise, but in order to gauge the problem, you need to perform controlled, scientific tests.
The next stage, which he has said he will be doing, is to find a way round the problem. This is much easier when you have accurate measurements to start with.
You are assuming that Apple can not and has not already chosen the best compromise to deal with this? Apple just slapped an antenna on the outside then said "oh that's why nobody else does that". Apple thinks more than any other company about what makes a plesant experience for it's customers. This design isn't a "mistake". It's a carefully considered compromise between phone size and reception. Apple isn't perfect but they also aren't sloppy when it comes to product design.
Scientific research to establish that the presence of a large conducting body near an antenna will detune it or cause it to be mismatched to the characteristic impedance of the feeder ???
I think you might well find a large, if not massive, body of research showing this. Stretching back a good few decades, if not to the birth of RF Communications (well, post-spark transmitters anyways).
This is why MIMO doesn't work as well as it might - one antenna impacts on the performance of the other.
The general principle is not what was researched here. What was researched here was the specific effect under specific conditions.
We've known F=ma since before the invention of the automobile, but it wasn't until tests showed the results of application of that principle under highway collision conditions that auto manufacturers started thinking seriously about safety features.
As most of the actual Catholics are outside waiting to see the Pope. Those who have risen far enough up the power structure of the church to be in the Vatican in uniform on the other hand have got there not through being good Catholics but by being good politicians.
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There is no simple answer (as you might have guessed) as you have a number of conflicting aspects to antenna design.
In general, if you are talking about an electrically small antenna (i.e. physically much less than 1/4 wavelength, etc) then you might find that adding your fleshy touch improves reception by adding to the area able to intercept signals.
However, the converse aspect also applies (probably here), in order to make any antenna work efficiently they are normally in resonance (i.e. tuned to a specific narrow range of frequencies) and by touching them you de-tune them and so make the job of getting power in/out of them more difficult. In addition, the body is not a *good* conductor, so tends to make the thing lossy and not only to re-tune it to a different frequency.
Over all I expect flesh decreases reception.
The iPhone problem is certainly *not* unique, just that the close proximity of the antenna to the hand makes the effect significantly stronger, and on top you have Apple's attitude to the problem with their high-end device where style has prevailed over best-practice RF engineering.
The conductivity of skin to stainless steel is so low it can be discounted. What is more likely is you're creating a capacitance, but any antenna reasonably close to a plastic case would have the same effect (and in fact this appears to be true as the issue isn't unique to the iPhone 4).
Where the iPhone 4 is different is the spot where this is most likely to happen has a line across it. So if you want to demonstrate is then it's quite easy (cover the line with a finger). Conversely if you want to avoid the issue then don't put your fingers over the line (hence the much quoted; "you're holding it wrong"). However such spots exist on other phones too, they just aren't as clearly marked ;-)
"...Apple's attitude to the problem with their high-end device where style has prevailed over best-practice RF engineering."
If Apple had owned up to it whether saying it was a design flaw or a design decision, the flameage would not have been as intense. Granted saying design flaw would probably have been more expensive as people would then have expected them to FIX the design and retrofit it to all the devices already sold, but it would have reduced flameage.
Not spent any time in the field of RF design then?
At some wavelengths and in certain circumstances touching an antenna can result in an increased ground plane effect which might improve reception.
That's not true for UHF or microwave.
The issue here is that the finger bridges two different antennas creating a new hybrid metal/person/metal antenna that is severely compromised for any of its intended uses.
Wow, wouldn't have guessed. Holding ANY phone degrades the signal - I see it on my iphone 3gs + 4, also on my ancient nokia dumbphone and my wife's new nokia dumbphone.
And the bumper: it's there to prevent the antenna bridging, and works brilliantly. With my iphone 4, I can kill the connection most of the time by holding it tightly. With a case, the effect is minimal (no worse than the other phones anyway).
Can I get a large research grant for typing that please?
"no worse than the other phones anyway"
You people keep saying that even though it is totally and utterly wrong.
While all phones may have a reduced signal in certain circumstances, the iPhone 4 has a special, additional problem all of it's own. That is what this research is saying.
No one is going to give a grant to person who has difficulty comprehending basic information.
"And the bumper: it's there to prevent the antenna bridging"
No. It's sold as insurance against the 4's well documented reception problems not specifically to prevent "antenna bridging". Look like it doesn't work.
"then with the antenna actually in contact with a "thumb phantom" with the same dielectric properties as human skin."
So they didn't actually test it with an actual human thumb attached to an actual human person? How then can any reliable conclusions be reached? All they've demonstrated is antenna performance in an unnatural laboratory situation that assumes their replacement mimics all the variables of the real-life scenario.
They can say that the "phantom thumb" mimics the human thumb, but without a comparison performed in the same experiment how do they know? It's an assumption that may not be true.
It's quite a common ailment amongst fanboys.
No doubt someone will also attempt to explain how holding the precious while using it with no measurement equipment other than the reception bars is far superior to controlled conditions in a lab performed by an expert in the field.
Never mind guys.. Tell us again about the market cap..
Selective indeed. If you read what it says, the whole point of the experiment was to see what the difference a "bumper" made. Which they did not test with a real thumb or real hand or real person.
The test you are referring to was when the phone was held to demonstrated that it "reduced sensitivity" of the antenna. Which is not news to anyone, and wasn't the point of the experiment.
"if my iPhone 4 was 100 times less sensitive"
You forget that 100 times is 20dB, a big but not catastrophic difference to something like a mobile phone.
True that in free space it would represent a 10 time difference in distance, but in most mobile situations (e.g. in a city) you are pretty close to the base station and the phone can adjust its power to compensate, probably by over 20dB, so you see little effect on operation just a shorter battery life.
So you tend to get dropped calls when the network is busy and/or where you are further from the base station (but still in the nominal coverage zone).
One of the chacteristics of 3G/GSM phones is that they (and the base station) adjust the power required to the minimum necessary, to limit interference and save battery life. Faced with a poor antenna, the phone will just blast out more signal. It would only be in situations where the signal is already poor that you'd actually see problems, dropped calls, etc.
I think the conclusion was that even with the antenna detuning the iPhone 4 had better reception than the iPhone 3.
And if a bumper does not help then why not expose the antenna rather than sticking it just inside the plastic case like most smartphone do? Then iPhone 4 with a bumper is exactly like the iPhone 1-3 antenna placement wise.
My own experience with the iPhone 2 and iPhone 4 is that I get a little better reception with the iPhone 4. I use a bumper for glass protection but will probably remove it after a year or so when the phone isn't so shiny.
No real surprise, really.
Anyone who has messed around with radio antennas knows that you can receive some rather strange results. Even today's digital TV signals present some very interesting situations. Such as the orientation of a LCD monitor some feet away from either the TV or the antenna. It changes the reflected signal. And at marginal receptive times, the effectiveness of the antenna can be observed. Some have even claimed that getting up to take a break affects the signal. No doubt it can happen.
Touching the antenna does detune it. And being nearby can do so as well.
Surely this can affect any handheld device. You have a big bag of mostly water so near the antenna. And that can affect the signal.
Only an idiot would design an antenna that in normal use is being touched by the user. Holding it just so probably helps. But, it is a bad design decision. Would you buy a car that heads into the ditch if you do not hold the steering wheel just right?
er no, cars go straight ahead if you take your hands off the wheel (assuming the wheel was straight to begin with)
If your car is heading ditchwards, I'd take it to a garage ASAP and get it's alignment done quick-smart, because you're wearing your tyres unevenly, and could have them fail on you.
If your front-end alignment is ok, then it might be that you're experiencing the 'crown of the road'. Put simply, roads are not 'flat' but curved slightly, with the center slightly higher than the outside edges, so that water goes to the side, for drainage, reducing ponding.
Cars aren't designed to drift into the outside. Roads are designed to drift all uncontrolled objcts to the outside. Look up "camber" and you'll understand.
The better analogy is not buying a car that drifts to the outside of the road if the wheel isn't properly held, it's buying a car that drifts out because the wheel CANNOT be properly held.
Way back when Montgomery was chasing Rommel around the deserts of North Africa, the tanks had No. 19 sets which had an HF (High Frequency) main transmitter/receiver and a UHF transmitter/receiver compromising, I think, only one or two valves (tubes in North America) - the oscillator was also the 'power' amplifier, the other tube being the FM modulator. (See: < https://secure.wikimedia.org/wikipedia/en/wiki/Wireless_Set_No._19 >. The UHF unit is next to the power supply connector).
Apart from the tanks in the desert disrupting UHF transmissions in the UK (really), these UHF units could also be detuned off the operating frequency by grabbing the short antenna.
But I guess the Apple antenna specialists are more interested in re-inventing the wheel. Even square ones.
these UHF sets were just for squadron inter-tank chat and had a power level of under one-quarter watt.
I never heard of anyone dying, or even getting burned, by grabbing a quarter-wave dipole.
The desert UHF sets jamming the assembly areas for D Day in the UK were due purely to 'skip'. These days 'skip' signals can't be heard because of the traffic carried on UHF.
The funny thing is, when I was camping in some remote spots this (southern) summer, very often the people with iPhone 4's were happily using SMS or on the internet while other types of smartphones had nothing at all.
When you're not bridging it, the external antenna works brilliantly.
How is it when you touch an old fashioned VHF antenna the signal improves but this effect is reversed on a phone? In fact everyone knows by now that remote car unlockwidgets have a longer range when held to the head. And in another story... my old Audi manual stated not to use a mobile phone inside the car without an external antenna as the signal was increased to dangerous levels within the car.
Paris, because I've seen her MIMO
*Some people don't get innuendo, so... Claiming WMD is just a convenience to excuse military action and excuse not getting involved in countries without oil.
I think you will find that in the US any grenade or dynamite stick is now classed as WMD as the recent arrest of a Texan wannabe-terrorist shows. I'm sure it is just a matter of time for this to cross the Atlantic and we will soon see yoof found in possession of fireworks charged as if they were planning to set off a nukular explosion.
VHF radio uses radio frequencies which are much much longer wavelength than those used by mobile phones - and therefore behave differently when a big bag of water gets in the way.
However, you can still upset the antenna matching even at VHF wavelengths if you grab it in the wrong place.
The other thing to bear in mind is that a radio receiver is not as sensitive to a miss-matched antenna as a radio transmitter is, a receiver will continue to function quite well or even improve slightly, whereas a transmitter will lose lots of effective power - or in extreme cases fry itself - when attached to a badly miss-matched antenna.
As a mobile phone needs both a transmitter and receiver to function, it is the transmitter bit that suffers.
So the "Antennagate" episode still has not been laid to rest!
I need to ask who who paid for this research? I do understand Universities are meant to research issues, but does the iPhone need or deserve this type of attention?
No wonder the government of the day are reducing funding and increasing tuition fees, universtities are squandering time and money flogging dead horses and/or researching the obvious
Now Mr. Uni Boffin, go research something meaningful like the fact that Global Warming is a natural process and not a man made issue. Hopefully the new government will read your useful research and not impose any more "green taxes" on us
Remember the stories of vibrating cellphones placed in odd areas of the body? By accident of course but what_kind_of_antennae_did_they_use? Enclosed by a body, yet still able to receive calls for that vibrating effect?
Yeah, conduct THAT test! (I pick Chris 19 - since he didn't submit the proper paperwork for the research grant to get paid for his typing and subsequently gave his work away)
[email protected]:19 - depends. FM you become part of the circuit, AM you're a big resistor. Wavelengths and stuff I don't want to look up right now - it's complicated lol
Paris, cuz she knows where to hide stuff.
Add a large crank on the side and a purple lamp glowing brighter the better your antenna is tuned - it worked in Soviet tank radios since the 60's, so why not on the Jobsphone?
Yes, it is that wheel in the middle with a chrome-plated folding crank and the bright red nut on it and the light above....
So the conclusion of this research seems to be that all smartphones suffer from signal loss problems when held in the wrong way.
I seem to remember Apple posting this exact same conclusion last year, with demonstrations on a number of phones...
Not sure how you've managed to spin this story into a criticism of Apple antenna design, given that it reaches exactly the same conclusion that they did.
"So the conclusion of this research seems to be that all smartphones suffer from signal loss problems when held in the wrong way."
That's not the conclusion of this research. You are either a bit dim or doing some spinning of your own.
Just in case it is because you are dim here is the real conclusion again:
"iPhone 'Death Grip' effect is real, plastic cases don't help"
I won't buy a car that won't work as a car, but many people will. You can however argue that not holding steering wheel correctly, can cause problem on rough road. A better expression would be: Apple sells new iCar, you have to dress in certain way, or else the car will not start/ will likely to crash. Drive in your shorts and T, you are dressing wrong.
However, fanboy/girl lives in Jobs' fantasy walled garden, not real world. They will buy any crap Apple sells at any asked price.
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I held out on an iPhone 4 because of the original version of this story - but then I got an AR Drone for christmas and my ancient 3G just couldn't hack it
and you know what, I just don't get signal degradation *that-I-notice*
perhaps its coz here in the Netherlands we have good signal coverage? I have no idea. Perhaps it's coz the actual effect in real life is nominal?
It seems like anyone can take the facts and spin them however they want to support or criticise the iPhone. but at the end of the day the facts (in my humble opinion are):
Put a human water bag next to an antenna and you get detuning (This is not a smartphone phenomenon)
Make a human water bag touch the antenna, and the detuning is worse.
Bridge the void between 2 separate antennas and you get further detuning
This detuning in itself is not enough to cause serious signal loss. However, couple that signal loss with an already low signal and you get sufficient signal loss to cause problems.
So all smart phones have this issue with detuning. Apple said this. It just so happens that Apple put their antenna(s) on the outside.
So in the situation where you have:
Human meat sack + bridged antenna + low signal area = Dropped calls
However, from what I have heard (as I do not have an iPhone 4) the iPhone 4 for the most part has far superior reception in most cases, death grip or not. Combine that however with bridging, and low signal, and maybe a fair distance from the cell tower and you get dropped calls.
So my summary of all this is iPhone 4 has a nice design and the antenna on the outside in the most part produces good results. However, throw a low signal in there along with the detuning and you have dropped signal.
At the end of the day I have a Dell Steak, so I better move on now and charge it for the second time today.
By the way, I cannot use my smartphone in my living room. The kitchen is fine, but the living room is a no. It doesn't matter how I hold it, or which chair I stand on, or whether I am swinging from the lamp shade or not, it won't get a signal. What's that about?
Calling someone a moron is very rude. Calling someone a moron because you didn't understand the reference makes you look very rude and silly.
Completely reliable and reproducible. If I hold the phone in the usual non-Jobsian way, the bars drop and the call dies.
If I delicately grasp it by the top edges only - as if it were a thing of almost infinite value, trembling poetically with lambent aesthetic wonder - I can make calls that last a few minutes. Until I forget what I'm doing in the heat of the convo and accidentally touch its forbidden areas again.
Pile of pants if you ask me.
So what do they suggest we use, then?
Correct me if I'm wrong but don't pretty much all wireless consumer electronics employ plastic insulation between the user and the antenna?
So from this can we conclude that wireless devices historically have always worked in a much-degraded capacity, and if we solve this problem then they will perform much better?
Am I reading this right?
From what I gather they're saying most cases don't help the situation but that the iPhone 4 has a problem that "hasn't been investigated before" - this suggests they realised they needed to do further tests with the iPhone but didn't?
Add me to the list of people who will have tested this then. Successfully death-gripped with no bumper - no change in signal with the bumper on
(oh, and fwiw I can only recreate the signal dropping when intentionally wrapping my hand around the phone. Using it normally in my left hand does nothing)
There is no great surprise here. People effect aerials, every antenna designer knows this and so does joe public; if he thinks about it. It's generally understood that you do not stand next to portable tv aerials.
Apple have tried to do the right thing, maximize the volume of your antenna to maximize it's efficiency. The difficulty they have come against is that also makes them easier to detune. If you were going to be clever you would measure reflected power and have electronic tuning, but that is added cost and space.
Also this has nothing to do with MIMO, that's a whole different field, if you pardon the pun.
If the antenna detunes due to extra capacitance when it's held in the hand, it's simple enough to tune it the other way to start with.
I learned this a long time ago making helical 2GHz antennas - when we slipped a plastic shroud over them the resonant frequency changed. The solution was simply to set the free-air resonance a little higher.
Similar tweaks were done with pagers many years ago. They _required_ being held or worn in order to achieve maximum sensitivity.
On the other hand: Bridging the gap in a skeleton slot antenna will lead to all sorts of wierd effects and a guaranteed loss of sensitivity.
Mine's the one with a Smith chart in it.
.... after strenuous, two-handed, multi-fingered efforts, I'm unable to budge the signal strength indictor off 3 bars as I sit here. Perhaps the GSM unit is different: the antennas have been redesigned for CDMA. Scant comfort for UK/Euro iPhonebois, if true.
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