I've tried Mr Google, but I cant seem to find any tables about how bad plastics are at absorbing RF.
For fun, I'm just about to make Jason Heckers' helix antenna
Any links?
martin
I've tried Mr Google, but I cant seem to find any tables about how bad plastics are at absorbing RF.
For fun, I'm just about to make Jason Heckers' helix antenna
Any links?
martin
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?
-- Jim Yanik jyanik at kua.net
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 :-)
-- Thanks, Fred.
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.
-- Jim Yanik jyanik at kua.net
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
-- "it\'s the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com
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.
-- JosephKK Gegen dummheit kampfen die Gotter Selbst, vergebens. --Schiller
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