On 19/05/16 19:37, Tim Streater wrote:
In article , Chris Hogg
wrote:

On Thu, 19 May 2016 18:24:00 +0100, Graham.
wrote:

On Thu, 19 May 2016 10:04:14 -0700 (PDT), wrote:

On Thursday, 19 May 2016 17:44:04 UTC+1, John A Knight wrote:
replying to MM, John A Knight wrote:

http://www.scienceabc.com/pure-scien...our-microwave-

oven-develops-a-hole-in-it-will-the-waves-leak.html
snip

That site's info re hole size & leakage is complete ballcocks.


https://groups.google.com/d/msg/uk.d...I/WSBDBrNF0GkJ

Clearly the OP needed to buy a new microwave, but from an RF
perspective the information on that scienceabc.com page is actually
quite accurate.


I thought it was complete ******** too; it treats microwaves as if
they're tennis balls, but I'm no microwave expert. If it's not
********, and if microwaves can't leak out of a hole smaller than 12
cm. why all the fuss in the past about microwaves leaking around
ill-fitting doors, and why the need for a fine mesh across the window
in the door? If the article is OK, you barely need to shut the door,
let alone worry about leaks around the edge, and wide-mesh netting
would do in the window allowing a much better view of the contents.
What am I not understanding?

This issue is nothing specifically to do with microwaves. It relates to
*all* sorts of waves and their behaviour. Look up diffraction. I'd do
it meself, but SWMBO has just announced that the scoff is ready.

The issue us not diffraction, but reflection.

You don't need a perfect surface to reflect.

Its the same principle as using a yagi array or similar. The presence of
the metal bits affects propagation around a far greater volume than they
physically occupy, because a field is induced in the nearby areas.

--
"When one man dies it's a tragedy. When thousands die it's statistics."

Josef Stalin