All true, and probably "cone" wasn't the correct term, but I wasn't
thinking so much of a wave guide (for amplification) as a shield (to
block signals from all but one direction)

For instance, shaping the foil into a high-walled bed, and placing the
iphone on a non-conducting "mattress" to insulate it from the foil
would tend to have much less signal from the directions blocked by the
walls of the bed.

Yes, it would be crude, and approximate, but the laptops used in wifi
site surveys aren't *that* much better, I would think.

But, I bow to your superior knowledge on this, and won't feel too
embarrassed if you shoot me down.

Kurt

On Sun, Oct 11, 2009 at 01:40, audionyx <audionyx (at) gmail (dot) com [email concealed]> wrote:
> To make a waveguide, some math will be involved (and an understanding of how best to couple it with the antenna input). But the more important element will be consistency. I mentioned that holding the device impacts reception pattern because -- it does. But so would holding the aluminum foil cone near the device, at least by simple loading. If the position can be maintained (and at this wavelength, it shouldn't budge and the phone should maintain consistent polarization), it would distort the reception pattern just by being there (whether or not it was used as a waveguide).
> [Sorry... I'm an EMC guy- RF interference and measurements. And I can ramble.]
> The point was that the phone cannot truly be omnidirectional because the person who holds it influences the reception pattern. Even in product development, a human body model won't represent the diversity of bodies perfectly. An average of them, yes. But everyone is unique enough to cause sometimes not-so-subtle perturbations in the pattern.
> So, going back to the premise that it couldn't work as advertised due the reception pattern symmetry, that's possible but I wish they had something like for a BlackBerry!  :-)
> It ultimately comes down to maintaining position of the receiver and its elements, including a cone or waveguide's position relative to the device, and how the software is processing information.
>
>
>
> ----- Original Message -----
> From: "Kurt Buff" <kurt.buff (at) gmail (dot) com [email concealed]>
> To: "Sec" <wifisec (at) securityfocus (dot) com [email concealed]>
> Sent: Saturday, October 10, 2009 1:24:26 PM GMT -06:00 US/Canada Central
> Subject: Re: WiFiFoFum radar
>
> Has anyone considered the power of .25 sq ft of aluminum foil, folded
> into a small cone, or something similar? It would hold your iPhone,
> and provide good directionality.
>
> Kurt
>
> On Sat, Oct 10, 2009 at 08:25, audionyx <audionyx (at) gmail (dot) com [email concealed]> wrote:
>> Has anyone considered that, when a phone is in the hand of its user, it's unlikely to be uniformly omnidirectional and, instead, may have a pattern with lobes? If this were the case, one direction will probably be most sensitive. Once that pattern is established, then I would suspect it wouldn't be too difficult to plot signal strength against it. Of course, influences of the building's structure (pillars, walls, cube frames, coke machines) would impact the placement of perceived radio sources.
>>
>>
>> ----- Original Message -----
>> From: "Geoff Armstrong" <geoffarm (at) exchange.ubc (dot) ca [email concealed]>
>> To: "Robin Wood" <dninja (at) gmail (dot) com [email concealed]>, "Mike Kershaw" <dragorn (at) kismetwireless (dot) net [email concealed]>
>> Cc: wifisec (at) securityfocus (dot) com [email concealed]
>> Sent: Friday, October 9, 2009 8:55:29 PM GMT -06:00 US/Canada Central
>> Subject: RE: WiFiFoFum radar
>>
>> I tested wififofum radar in a building with 40 AP's.. It was totally
>> off. It's a guess at best.
>>
>> The scanning feature is nice though.
>>
>> -----Original Message-----
>> From: listbounce (at) securityfocus (dot) com [email concealed] [mailto:listbounce (at) securityfocus (dot) com [email concealed]]
>> On Behalf Of Robin Wood
>> Sent: Friday, October 09, 2009 1:59 PM
>> To: Mike Kershaw
>> Cc: wifisec (at) securityfocus (dot) com [email concealed]
>> Subject: Re: WiFiFoFum radar
>>
>>
>> My theory was along the lines of your second but I was stuck on how if
>> you turned it on in a location it knew where to place them for the
>> first position. We didn't test that so it may just randomly distribute
>> them round the map and work it out once you start moving. As it has a
>> compass built in it knows which way you are walking and if it is
>> getting weaker the signal will probably be behind you.
>>
>> Robin
>>
>

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