@Doctor Who: If you are not using the phone on the WLAN connection then it doesn't matter because the cell signals are on a different frequency from the router's possible frequencies.

I am using the WLAN of my router with my phone.  Saves having to use my 3G connection when I'm home.

12 minutes ago, Doctor Who wrote

Does it matter if I have my phone close to a PC monitor?

No, but watch out for your mouse and keyboard. Whenever I have my iPhone close to my keyboard I sometimes get a stream of 'ssssss' characters sent down the line. I have no idea why this is, but presumably interference as my keyboard isn't shielded from radiation - neither are speakers and mobile phone interference with speakers is most irritating.

But it depends on various things like signal strength ratio of the two signals, the type of receiver circuit, the ability of the receiver to reject frequencies outside the band (it is not infinite), etc, and it may or may not be a problem in this case.

The frequencies thrown out over the analog air are not nice clean entities.  Signals change over distance and with other environmental effects.  Receivers are tasked with filtering out the noise and letting in the signals that most accurately fit the channel.

@Bas: antennea explode ... that's funny.  It isn't like the router is microwaving the phone or vice-versa.  The power involved in the signals is not that high.  It is just less optimal (i.e. prone to more wireless errors) when they are very close.  If I had a megaphone (me router) and you did not (you phone) and we stand face to face and try to carry on a conversation we will be successful.  However, you will need to work harder to discern what I'm blasting at you.  I will probably have to repeat myself at various times throughout the converstation but eventually we will be successful.  It is not "optimal" but it will work.  When I back off a reasonable distance our conversation is more likely to be successful without as many repeats.  Not to mention your receivers (ears) won't ring anymore.

Some more info.  The lower the frequency the better the choice for an environment in which the singal needs to bounce.  The higher the frequency the better the choice for an environment in which the signal needs to penetrate obstructions.  Lower frequencies are better for shorter distances but a wider cone of coverage.  Higher frequencies are better for longer distances and a shorter cone of coverage.  Higher channels equate to higher frequencies (I believe that is the case for all signal ratings but correct me if I'm wrong someone).

NOTE: post a correction to anything I have stated wrong.  My knowledge is learned from doing wireless surveys in the past and nothing from a formal school.

@Doctor WhoW3bbo: I think every electronic device emits some level of EMI (electro-magnetic interference).  The degree of shielding and power involved will vary by device, manufacturer, etc.  I had an old CRT monitor (way back) that would create a 3 foot wireless black hole across all 3 dimensions.

It is just less optimal (i.e. prone to more wireless errors) when they are very close.

I had no idea that this would be the case. Weird. Thanks!

1 day ago, davewill wrote

@Doctor WhoW3bbo: I think every electronic device emits some level of EMI (electro-magnetic interference).  The degree of shielding and power involved will vary by device, manufacturer, etc.

Indeed, and that's the basis for banning the use of electronic devices during take-off and landing of an aircraft. In practice, almost nothing you carry actually has much chance of interfering (even a cell-phone not set to airplane mode), but from the FAA's point of view it's easier to ban everything than to try and determine exactly which devices are safe and which aren't, and from the flight attendant's point of view it's a lot easier to check if someone's using a device rather than what device they're using and whether it's on the safe list.

@elmer: An acquaintance of mine had their computer in the kitchen, near the microwave. This created some weird interference effects on the (CRT) monitor whenever the microwave was being used. This did not speak well of the shielding of either the monitor or the microwave.

When I took it apart I realised that I might not have replaced every screw last time I opened it up.  This may have been the cause of my native camera app not working anymore (although a third party app worked) Also my headphones remote stopped working.

Anyway after putting it all back together again I realised I have failed to replace a small piece of metal which I seem to remember came from where the battery connects to the motherboard.

It seemed so small and insignificant and I had already spent a couple of hours on it, I threw it in the bin.

Well the consequence is that now unless I am about 12  inches away from the wireless router I am unable to get a signal.  

I'm guessing this may be to do with battery interference of some sort. I am also now worried about brain tumours, and I can't keep the phone in my jeans pocket anymore.

Oh well, roll on the iPhone 5

It seemed so small and insignificant and I had already spent a couple of hours on it, I threw it in the bin.

@leeappdalecom: that made me laugh out loud.    I wonder if that small piece of metal was the connector for the antennea.