A most interesting discussion. Certainly on interesting test of the laws of
superposition in passive circuit design.
I tried to explain the concept to my wife yesterday (she is electronics
challanged) and the response I got was,
"You sure as _hell_ not going to use _my_ cell phone for that. I don't want
it zapped in the microwave."
But, I can't figure out why anyone would care in the first place. What with
thousands of cell phones (both hand sets and the transmitting towers dumping
who knows how much RF into environment, I'm sure not concerned about a
little stray radiation while I nuking a bit of H2O for afternoon tea!
Best to all and nuke on everyone,
Bob Smith
--- Avoid computer viruses, Practice safe hex ---
-- Specializing in small, cost effective
embedded control systems --
http://www.smithmachineworks.com/embedprod.html
Robert L. (Bob) Smith
Smith Machine Works, Inc.
9900 Lumlay Road
Richmond, VA 23236 804/745-1065
[EMAIL PROTECTED]
----- Original Message -----
To: "Multiple recipients of list CHIPDIR-L" <[EMAIL PROTECTED]>
Sent: Friday, December 12, 2003 12:44 PM
> On Fri, Dec 12, 2003 at 08:54:29AM -0800, Alois Bauer enlightened us
> thusly
> > >
> > > > An interesting idea for testing your microwave cooker was passed
> > > > to my wife. If you want to test your Microwave oven for leakage,
> > > > put your mobile phone inside, and call it. If it rings, the
> > > > microwaves got in, so they could get out, therefore it's leaking.
> > >
> > maybe this test does not prove low or high leakage at the MW cooker's
> > working frequency of typically 2.45 GHz. As it is not neccessary and
> > more expensive to make broadband (in frequency) RF gaskets for a
> > single-frequency application, often resonant structures are used. For
> > example the width of the overlap of the oven's door is made lambda/4
> > wide and the contacting zone is only in the inner edges. The
> > surrounding gap acts like a waveguide (like a slotline) which an open
> > end around the outer edges of the door. This open is transformed into
> > a short, in reality in a very low impedance after one quarter of
> > wavelength. Low impedance means that the electric field there is quasi
> > shorted and so nearly no energy can escape althoug there may be a
> > mediocre ohmic contact between door and housing. As the mobile phone
> > works at a significantly longer wavelength (f = ca. 900 MHz) this
> > trick with resonant RF gaskets does not work any longer. So little
> > isolation at 900 MHz does not neccessarily mean little isolation at
> > 2450 MHz. It depends on the design principle of the RF gasket.
> >
> > A simple detector could be built, to check if and where microwave
> > energy escapes. You only need e.g. a Schottky diode with < 1pF
> > capacitance (hp 5082- 8035) and a blocking capacitor of 10 to 100 pF
> > in preferably chip outline (size 0805, 1206) and two resistors of some
> > kilo-ohms plus a voltmeter as indicator. The probe should be mounted
> > e.g. at the tip of a wooden rod. The both leads of the diode between
> > capacitor and diode body should be about 1 cm in length and act as
> > magnetic antenna (shown as "L" in the schematic below). The resistors
> > decouple the detector from the connecting wires to not perturb the
> > electromagnetic field to much.
>
>
> Does a voltage develop, or does the diode leak (more)? How sensitive
> would the thing be?
>
> --
>
> With best Regards,
>
>
> Declan Moriarty.
> --
> Author: Declan Moriarty
> INET: [EMAIL PROTECTED]
>
> Fat City Network Services -- 858-538-5051 http://www.fatcity.com
> San Diego, California -- Mailing list and web hosting services
> ---------------------------------------------------------------------
> To REMOVE yourself from this mailing list, send an E-Mail message
> to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in
> the message BODY, include a line containing: UNSUB CHIPDIR-L
> (or the name of mailing list you want to be removed from). You may
> also send the HELP command for other information (like subscribing).
>
--
Author: Robert Smith
INET: [EMAIL PROTECTED]
Fat City Network Services -- 858-538-5051 http://www.fatcity.com
San Diego, California -- Mailing list and web hosting services
---------------------------------------------------------------------
To REMOVE yourself from this mailing list, send an E-Mail message
to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in
the message BODY, include a line containing: UNSUB CHIPDIR-L
(or the name of mailing list you want to be removed from). You may
also send the HELP command for other information (like subscribing).
