2.4GHz absorption by plastics

Duh, put it in the microwave and see if it melts. ;-)

Offhand, polypropylene Gladware containers are microwave rated.

Tim

-- Deep Fryer: A very philosophical monk. Website @

Yeah I know the microwave trick, but I never intend buying one.

thanks for the polypropylene pointer

martin

Check any reference book on electric materials. PVC is one of the most lossy. Polyethylene and teflon are the best. However it should not be very important for that antenna.

Vladimir Vassilevsky

DSP and Mixed Signal Design Consultant

Put your plastic in a microwave oven. Nuke it for about 20 seconds. Is it warm? Then it absorbs microwaves. If cool (it probably will be) then it doesn't.

none of my neighbours have microwave ovens, neither do I :( or maybe :(

martin

martin griffith wrote in news: snipped-for-privacy@4ax.com:

YOWZA..nothing like staying back in the Stone Age. ;-) I've had the same MW for almost 30 years.

WHERE do you live?

Well, now is the time to buy one and write it off as an R&D expense :)

On Tue, 17 Jul 2007 01:24:00 +0200, martin griffith wrote: ...

Good grief! What planet do you live on? ;-)

Cheers! Rich

These days you don't even have to buy one - you can find them in dumpsters, and they usually only need a fuse. (I've re-fused [no pun intended] ovens that then lasted another 5 years.)

But I'd say if the original uses PVC, then PVC must be good enough. :-)

Good Luck! Rich

In a little white village

The kitchen is so small, there isnt enough space to put a MW !

martin

martin griffith a écrit :

There're some nice pics... and you have a good eye :-)

martin griffith wrote in news: snipped-for-privacy@4ax.com:

they make some pretty small MW ovens these days. In my Indy apartment,I kept the MW on top of the refrigerator. And it's a full-size oven,not a sandwich-size model.

most plastics avsrob very little em energy, this is related to the dissaptaion factor for a given material.

for a raidted wave, the relfection loss, obtsined from going from air to plastic, then plastic to air, gives a reflection loss .. this is an order of magnitude or greater thsn dissaption factor for ost plasics. the refletion losses are relate to eR the dilectric constant for the material.. if you want more loss...l add little rsitors on a wave space level to the material to increase losses. to decrease losses add....air :-) good luck and Best Regards,

Marc popek

I see a 600W Sharp that can take a dinner plate and is only 13" wide (a 13" cube in fact):

Best regards, Spehro Pefhany

Ah, Spanish kitchens, the bastard architects only put two accesable power sockets in as well. Phone lines and TV distro in each room, but not in the kitchen!

I am a bit too old to change my cooking habits, ( a monster wok) and I'd rather put the money towards a new scope, and a new flint for the soldering iron

martin

Thanks, I think I spotted a VSWR meter circuit for 2.4G somewhere, might be worth investigating

martin

So take a piece of the plastic you want to test to the microwave oven store and ask for a demo. ;-)

(Or, just use the same PVC as the guy who wrote the page did.)

Good Luck! Rich

Ok. I'll quit moaning :)

martin

Maybe, maybe not. Microwave absortion is very frequency specific (molecular resonances). Microwave oven characteristics (typically 2160 Mhz) may not translate to WiFi bands, just a few hundred Megahertz away.