iOS 4.0.1
in [UK Mac]
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From: Matthew Sylvester on 17 Jul 2010 08:42 ray <datasmog(a)hotmail.com> wrote: > If there are any antenna boffins in the group, please chime in, but my > understanding of antennas is, they are tuned lengths according > frequency. If you touch one you upset the tuned length. If you short two > antennas out by making them touch or by holding both of them you get the > same effect. > So why don't you see this when holding the IP4 in the normal way with > fingers touching both antennas? You're right, but where you touch the aerial has a great effect on the detuning - you can see that with the aerial on a normal radio, touch it in one spot and you'll wipe out reception but move an inch or two and there's no effect at all.
From: zoara on 17 Jul 2010 15:38 ray <datasmog(a)hotmail.com> wrote: > Martin S Taylor <mst(a)hRyEpMnOoVtEiTsHm.cIo.uSk> wrote: > >> Sak Wathanasin wrote >>>> As to whether there's any difference in performance, I can't say > > > > I've >>>> noticed >>>> anything yet. >>> >>> Presumably the iPh4 is fast enough that you wouldn't have noticed > > > any >>> performance problems anyway, but has it helped with the holding-the- >>> phone-kills-the-signal problem? >> >> It's made it a lot more obvious, I can say that! Before, the bars had > > a >> certain random fluctuation so it wasn't *totally* obvious that > > putting your >> finger on the black strip reduced the signal. Now it's very clear. >> >> Not only that, but putting your finger on the *other* black strip > > (the one at >> the top of the phone) noticeably reduces the wifi signal, too. > > This is what I have never understood about this problem. > What is it with the black strips and what does the steel bar at the > bottom do? The steel bar at the bottom is the same as the steel bar at the right; it's part of the UMTS/GSM antenna. The bar on the left is for Bluetooth, Wi-Fi and GPS. The black strips on the top and the bottom-left corner isolate the two antennae from each other. The black bar on the bottom-right is purely cosmetic. The first image on this page (from Apple's announcement) might clarify: http://www.anandtech.com/show/3794/the-iphone-4-review/2 > If there are any antenna boffins in the group, please chime in, but my > understanding of antennas is, they are tuned lengths according > frequency. If you touch one you upset the tuned length. If you short > two > antennas out by making them touch or by holding both of them you get > the > same effect. > So why don't you see this when holding the IP4 in the normal way with > fingers touching both antennas? I don't know. Bridging the top bar doesn't cause the same effect as bridging the bottom-left bar; don't know why as both these bars isolate the two antennae from each other. It seems related to capacitance or something. Using Sellotape over the bottom-left bar doesn't protect from the problem but using thicker tape apparently does. Inverse square law? I don't know. I can only trigger the death grip by directly bridging the bottom-left bar with one finger. Two fingers 5mm apart either side of the bar doesn't do it. A paperclip across the bar doesn't. -z- -- email: nettid1 at fastmail dot fm
From: Bruce Horrocks on 17 Jul 2010 16:46 On 17/07/2010 20:38, zoara wrote: >> This is what I have never understood about this problem. >> > What is it with the black strips and what does the steel bar at the >> > bottom do? > The steel bar at the bottom is the same as the steel bar at the right; > it's part of the UMTS/GSM antenna. The bar on the left is for Bluetooth, > Wi-Fi and GPS. > > The black strips on the top and the bottom-left corner isolate the two > antennae from each other. The black bar on the bottom-right is purely > cosmetic. > > The first image on this page (from Apple's announcement) might clarify: > > http://www.anandtech.com/show/3794/the-iphone-4-review/2 I'm not sure that that picture is correct. If you look at the iPhone video on the Apple site, at 5'15" you can clearly see that each of the black bars insulates the band. <http://www.apple.com/iphone/home/includes/video-iphone.html#video-iphone> -- Bruce Horrocks Surrey England (bruce at scorecrow dot com)
From: Pd on 18 Jul 2010 09:52 Bruce Horrocks <07.013(a)scorecrow.com> wrote: > If you look at the iPhone > video on the Apple site, at 5'15" you can clearly see that each of the > black bars insulates the band. > <http://www.apple.com/iphone/home/includes/video-iphone.html#video-iphone> If you look at 5'18" you can see that the steel is bridged across the right-hand black band, so although the bottom of the case is a separate piece of metal, it is structurally part of the right side case. Here's the relevant frame: <http://img.skitch.com/20100718-xgt3rgyygrs6ixr3euf4kceyr3.jpg> -- Pd
From: Martin S Taylor on 18 Jul 2010 18:16
zoara wrote > I don't know. Bridging the top bar doesn't cause the same effect as > bridging the bottom-left bar; don't know why as both these bars isolate > the two antennae from each other. I don't know why, either, but it seems from a quick inspection that bridging the top bar cuts down WiFi reception. Or am I imagining it? MST |