The weirdest (but working) iPhone 4 reception trick I have ever heard | Hacker News Reader

The weirdest (but working) iPhone 4 reception trick I have ever heard

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151 pointsBorisBomega37 comments

Not really weird. There's a boundary there between the air in the glass and the glass itself. So you've got a dielectric boundary and you'll get some reflection going on inside the glass. Lots and lots of things reflect radio waves to a certain extent. I'd guess that's what's happening here.

http://en.wikipedia.org/wiki/Non-line-of-sight_propagation#R...

I don't think by weird the op meant "Wow, this is a miracle that can't be explained by science." It was more along the lines of "Wow, this interesting and I would never have expected that to work. And boy would it look strange if everyone walked around with their phone in a cup."

And I agree with that statement. So yes it is weird, despite the fact that it has an explanation.

Is this a good illustration of the phenomenon?

http://i.imgur.com/cDgjD.jpg

The glass is the antenna and the shape (here a circle) radius at a given point is the signal strength at that point.

The glass is exploiting some anisotropies(?) in the cell phone signals. i.e. the red arc is somehow bigger than the black arc. I am using the circle as a way to depict an isotropic signal. If the signal is not isotropic, the shape would be somewhat more bulged in the left region (pear-shaped).

Sorry, IANAP, if someone can explain it better...

I think what OP is referring to is when light hits glass, some times it is reflected and sometimes it will move through the glass, depending on the angle it makes with the surface of the glass. So the signal is probably bouncing around inside the glass so the phone is able to pick it up.

If you stick it in a pint glass it makes the speakerphone a lot louder as well.

I can foresee some funny looks from strangers however, if you were to sit there in a bar on your own shouting at your phone in the bottom of a glass. Maybe that kind of thing is normal in california, I have no idea.

This was Amsterdam, people in Amsterdam are weird to Americans, so who knows :)

I suspect this is more about isolating the phone from the radio energy sinks of the human body (surface moisture on the skin & saline blood plasma) than anything to do with the glass itself.

Any suitably insulating (capacitive) enclosure (such as a "napkin swan", teacup, etc.) which preserves a largely vertical orientation (perpendicular to the local ground plane) should work just as well. We're still comfortably within the far-field http://en.wikipedia.org/wiki/Far-field performance envelope for transmission, but well within transmission-line power transfer regimes at these frequencies with a cell-phone-sized antenna.

If the glass were lead crystal (extremely unlikely in the bog-standard bar tumbler pictured), there's more potential for interference and a spatial locus of signal above the noise floor is possible. Typical window and utensil glassware is essentially transparent to these frequencies.

This seems like the most plausible explanation to me.

This is questionable. A couple stray observations for the boffins at HN:

1. Confirmation bias. Sure it works, because when it doesn't we don't think about it or publicize it on the net.

2. Glass holder removes your big meaty hand from the equation. Your hand absorbs radiation and is the equivalant of wrapping a phone in a steak.

3. Only works because the iphone radio is such a mess. You may be looking at bar strength changes that are happening anyway.

4. Works but because of orientation. Holding up compared to laying it down may give you better reception.

5. No controls. He should try this with a plastic holder or hanging it in the same orientation with a string. I wish the "aha I discovered something amazing" crowd would learn what controls are.

I love that people are thinking about confirmation bias, but you can't really "confirmation bias" your way from "I can't receive calls at all" to "Now I'm getting three bars and reliable signals of some types". There's an empirical state transition there, not just an opinion the way "I went from 2.1 bars to 2.8 bars" is unreliable.

So, he's in this uber cool restaurant, spending a nice evening with his daughter. And the first things he thinks of? Yeah, "checking in" and "tweeting". Am I the only one who finds this sad?

Those two things probably take 30 seconds total.

While typing from inside a glass?

Tested with an Apple Bumper case and a 500ml Arcoroc glass in my apartment: no effect.

Tested without the Bumper: still no effect.

Perhaps only certain kinds of glasses will work? Certain shapes or sizes?

yes only certain types of special glasses. you can buy them from my online store for $29.95

Sorry, I only want it if a) Jonny Ive designed it and b) it has a nice etched Apple logo on the side and c) it's an ideal size for quaffing fine bourbon.

There should also be a stainless steel band around the base which interferes with reception if you hold the glass the wrong way, ideally.

just tested it in our office in germany with o2 as carrier, went vom 1 bar to three bars in about 20 seconds inside the glass... amazing.

Why would it take 20 seconds for this to work? Radio is not slow.

Surely it's just a result of the bars being smoothed/some sort of running average of strength.

But if I move my iPhone around in the room, it seems to change pretty quickly.

To save power, the phone shouldn't be constantly trying to acquire a signal when it can't find one. It should try for 10-20 seconds, give up, then go to sleep, only waking every 30 seconds or so to try again, briefly.

Don't you guys remember Antennagate, where the following iOS update smoothed how fast the bars change? I bet if you did the same thing with a phone running iOS 2.0 it'd move instantly.

Most likely these are natural bar changes that are happening anyway. The glass or the "magic sticker that goes on your battery" just fools you into believing confirmation bias.

nope, its not, complete reproducable with 3 different phones.

Another datapoint:

There's no cell coverage in my basement. Sometimes you'd get 1 bar, but it will drop soon afterwards.

After putting the phone inside a glass, I have 3 bars. I took it out, held it by the charm (is that how it is called? The little string with a little figure that you can put on most phones today) and coverage dropped to 0.

Works for me.

The radiation pattern of the antenna is probably different enough with the phone in the glass to cause the network to switch it to a different cell tower altogether.

Also, "radio is fast" but signal-strength indicators are not updated at millisecond frame rates. :-P

I'm going to risk sounding like a dunce here, but IIRC some frequencies are more prone to bouncing off glass - for example in metropolitan cities with lots of high-rise buildings. While this is a detriment in the city, it could also be acting as a "satellite dish" making it easier to collect stay signals while also directing most of the transmission upward. Considering the antenna is supposed to be at the bottom of the phone the effect should be more pronounced as more of the glass can be used to direct the signal.

Am I crazy?

Mobile devices tend to operate in the 700 to 900 MHz range which translates to a wavelengths of several inches, so it's quite possible the geometry of the drinking glass is providing a bit of focus to the signal.

If you don't have a glass nearby, this also works when putting your 3GS (and probably other phones as well) at the same angle inside an upside-down clear plastic CD spindle cover. Went from 2 to 4 bars. Took the phone out, dropped down to 2.

It probably has more to do with antenna response characteristics due to polarization (antenna is similar to a j dipole http://en.wikipedia.org/wiki/Slim_Jim_(antenna) or a modified inverted V (since it's a U) maybe http://en.wikipedia.org/wiki/Inverted_vee_antenna ) + isolation from your hand. Without your hand (which is similar to a non-efficient ground plane) screwing up the antenna response, a vertical iphone would likely have better reception, especially if it's a dipole-like.

Also of note, most antennas at towers tend to be an array of dipoles with reflectors.

Your glass will always be half empty with an iphone in it.

I wonder, is the glass just holding the phone at the right angle for the polarity of the phone's antenna and the available signal to match up? If so, this trick wouldn't likely work places other than that restaurant.

Works on my cheap Galaxy Apollo in a pint glass - nice.

Could there be a metal component to the glass?

It could be lead glass.. http://en.wikipedia.org/wiki/Lead_glass

So....let's try it...here's the glass..in goes the phone..[20 seconds later]...dang...doesn't work...oh wait, wasn't there waterrrr.....sh##, double sh##... :P

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