Anand doesn't mention it explicitly, and neither do you, but I'm assuming that signal to noise ratio drops when you short the iPhone 4 antennae too otherwise his conclusion doesn't make sense:

"At the end of the day, Apple should add an insulative coating to the stainless steel band, or subsidize bumper cases. It's that simple."

The problem is that Anandtech's conclusion is out of place with the rest of their article, even if you take into consideration the shorting of the antennae.

The iPhone 4 loses 24.6dB of signal strength when cupped at the bottom vs 17.7dB for the Nexus one. If Apple should be required to add an insulative coating to the stainless steel, then shouldn't Google also be required to make their phone thicker (or make other adjustments) until it reaches the 14.3dB reduction of the 3GS?

If Apple is required to subsidize a bumper case, to bring the signal reduction down to 7.2dB, then shouldn't Google also be required to subsidize a case (even with a case, Google's signal reduction would still be 7.7dB).

Also, the iPhone 4 can hold a call quite well at the absolute minimum signal level of -113dBm. If the Nexus One can't do this, then should we demand that Google recall the Nexus one until it can do so?

This whole issue and the hundreds of news stories around it are ridiculous. This is not a black-and-white issue of the antenna working or not. The phone has a weaker signal for some people, and a stronger signal for others, depending on how you hold it and where you are. Take that into consideration when choosing a phone. If it's not working out for you, then just return the phone and buy one you like.

What does the Nexus One have to do with the iPhone's antenna issue? There is no oversite body that is 'requiring' anyone to do anything. It's not Nexus One owners that are complaining about the antenna issue, it's iPhone users.

Actually, the people I've heard about this non-issue the most from are Android evangelists and Apple haters that are looking for any reason possible to trash Apple. So it might make sense to compare it to their beloved Nexus One in a head to head comparison.

I believe losing 24dB of signal strength is roughly ten times worse than losing 17dB. As I understand it, there is no other phone out there with this level of signal attenuation problem. NB: I am not a signalology expert and only vaguely understand decibels.

As other's have noted, the number of dBm being received by an antenna is not really a very interesting figure. What is much more interesting is to know what is happening to the signal to noise ratio.

Imagine someone talking to you in a load bar. That person can, by shouting at you, make themself understood - but just barely. Although the signal is high, the noise (bar music, other conversations etc) is also high, and the quality of the communication is much reduced. That same person talking in a library could use a tone just barely above a whisper, and still be more clearly understood because the noise floor is so much lower in a library.

Many people don't realise that noise is actually the limiting factor in communications - if a signal has been attenuated, we can always just amplify it back up, but amplification amplifies the noise as well as the signal. Eventually, once the signal and the noise reach roughly equal amplitudes, amplification just gives you the noisy bar situation, you can't ever get back to the quiet library...

Bringing this back to the iPhone's antenna, we same to be in the library case, rather than the bar case. The signal that is being received when the antenna is being held is much quieter than what we see in other phones, but when we look at the only metric that really counts - bandwidth - we see that the iPhone is achieving consistently high transfer speeds, even when the antenna spacing has been bridged by someone's hand.

If I had to guess, based on the anandtech data, what we are seeing is an antenna that performs extremely well at reducing noise from the environment. Alternatively, the calibration of the sensor giving the signal strength readings in the 4G might not be terribly good. Either way, the independent tests done so far have all indicated that the iPhone 4G is outperforming every other phone out there at the moment, when looking at signal throughput.

An insulative coating? We're talking about signals in the 850 to 2300 MHz range - http://en.wikipedia.org/wiki/Capacitive_coupling anyone?

I don't know what that means.

Apple has claimed not touching the black gap or using a case helps. Random people online seem to think that sticky tape or nail polish can fix the problem. Anand seems to think some thin layer of diamond would do the job too.

Are you saying it wouldn't work? And if not could you explain why not, and what would be needed?

I'm also a suspicious of the insulative coating fix. I think the proposed solution hinges on the idea that electrically isolating the hand from the conductive surface of the antenna would prevent it from loading/bridging the antenna. While a thin insulating layer would accomplish this at DC, it may not at higher frequencies, especially when you get up close to the GHz range.

Your finger and the metal of the antenna are essentially two conductors separated by a thin insulator, which forms a capacitor. A capacitor blocks DC current, but its impedance (resistance) goes down as the frequency of the signal increases. What tesseract is suggesting is that the frequencies in the antenna are so high that our capacitor's resistance is practically nil; the thin insulator essentially does nothing to fix the problem.

A possible way to fix this is by lowering the capacitance of our capacitor. The simplest way to do this is to simply increase the distance between the two conductors, i.e. move the finger farther from the antenna. If you look at Apple's bumper case, you'll notice that it is far thicker than any of the proposed insulating layers.

I think that what he's trying to say is that at high frequencies thin coating is not enough. You've got a similar situation in capacitors where with no physical and conductive connection between the sheets, you get the effect of a good conductor of alternating current. You'd create a similar effect by coating the antenna and pressing your conductive (to some extent) finger on the coating - you'd be a part of a large capacitor.

How exactly would that affect the signal is up for discussion. It depends on how conductive is your body, what's the thickness of the coating, what area would be needed to create a visible effect, etc. etc.