elektroda.net NewsGroups Forum Index - Electronics Design - what material reflects microwave?
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whit3rd
Guest
Guest
Fri Aug 27, 2010 2:28 am
On Aug 26, 11:49 am, jgy2001 <jgy2...@gmail.com> wrote:
Quote:
What kind of simple material reflects microwave energy, such as
cellular and wifi signals?
cellular and wifi signals?
A conductor, or a material with high magnetic susceptibility,
will block radiation.
Quote:
I am thinking simple laminated material, such as film, or tape or
plastic sheets?
plastic sheets?
There are aluminized films, of course (but beware, the long
wavelengths
you are referring to will tunnel through a very thin film).
Construction
materials like aluminized foam insulation have thick-enough metal,
and there are nickel-containing conductive paints that do a DANDY
job, they both have conductivity and susceptibility on their side.
Seams must be made conductive, too, of course (there's a line of
3M tapes for this purpose). Doors with conductive gaskets are
used in screen rooms, those gasket materials are NOT cheap.
Nor, for that matter, are the tapes.
Paul Hovnanian P.E.
Guest
Guest
Fri Aug 27, 2010 3:14 am
jgy2001 wrote:
Quote:
What kind of simple material reflects microwave energy, such as
cellular and wifi signals?
I am thinking simple laminated material, such as film, or tape or
plastic sheets?
Can I embed simple film with some kind of simple metal to reflect
microwave signals?
Thank you.
Aluminum foil. Preferably hat-shaped.
--
Paul Hovnanian mailto:Paul_at_Hovnanian.com
------------------------------------------------------------------
Ask not for whom the <CONTROL-G> tolls.
David Eather
Guest
Guest
Fri Aug 27, 2010 7:00 am
On 27/08/2010 7:57 AM, Tim Wescott wrote:
Quote:
On 08/26/2010 02:07 PM, David Eather wrote:
On 27/08/2010 5:08 AM, Tim Wescott wrote:
On 08/26/2010 11:49 AM, jgy2001 wrote:
What kind of simple material reflects microwave energy, such as
cellular and wifi signals?
I am thinking simple laminated material, such as film, or tape or
plastic sheets?
Can I embed simple film with some kind of simple metal to reflect
microwave signals?
Metal, or just about anything that's metalized. Aluminized mylar would
certainly count as a "simple film", and is somewhat conformal if you
don't mind cussing a bit.
If you can't find it anywhere else find a hobby shop that caters to
model airplane builders and ask for metallic Monocoat, or check out the
hobby websites (Tower Hobbies is good).
The "Emergency Space Blankets" beloved by rescue and emergency services
are aluminized mylar and cost something like one or two dollars per
square yard.
Of course! Why didn't I think of that?
(please don't answer).
On 27/08/2010 5:08 AM, Tim Wescott wrote:
On 08/26/2010 11:49 AM, jgy2001 wrote:
What kind of simple material reflects microwave energy, such as
cellular and wifi signals?
I am thinking simple laminated material, such as film, or tape or
plastic sheets?
Can I embed simple film with some kind of simple metal to reflect
microwave signals?
Metal, or just about anything that's metalized. Aluminized mylar would
certainly count as a "simple film", and is somewhat conformal if you
don't mind cussing a bit.
If you can't find it anywhere else find a hobby shop that caters to
model airplane builders and ask for metallic Monocoat, or check out the
hobby websites (Tower Hobbies is good).
The "Emergency Space Blankets" beloved by rescue and emergency services
are aluminized mylar and cost something like one or two dollars per
square yard.
Of course! Why didn't I think of that?
(please don't answer).
I have lots of time, but little money on hand.
Paul Keinanen
Guest
Guest
Fri Aug 27, 2010 7:06 am
On Thu, 26 Aug 2010 18:50:24 -0400, "tm"
<the_obamunist_at_whitehouse.gov> wrote:
Quote:
How about single side PC board material? The real thin
stuff, 0.008 inch FR4 with 1 Oz copper is cheap. Check ebay.
stuff, 0.008 inch FR4 with 1 Oz copper is cheap. Check ebay.
Radio amateur often make boxes for subassemblies by cutting double
sided PCB boards into suitable plates and soldering these plates into
a box, with slightly overlapping sides. These boxes are mechanically
stable and good EMC isolation, so that small signal subassembly units
can be close to high RF power (10-1000 W) subassemblies.
John Fields
Guest
Guest
Fri Aug 27, 2010 12:00 pm
On Thu, 26 Aug 2010 13:46:20 -0700 (PDT), Rich Grise on Google groups
<richardgrise_at_yahoo.com> wrote:
Quote:
On Aug 26, 12:11 pm, mpm <mpmill...@aol.com> wrote:
On Aug 26, 1:49 pm, jgy2001 <jgy2...@gmail.com> wrote:
What kind of simple material reflects microwave energy, such as
cellular and wifi signals?
...
The material that is embedded in some microwave popcorn bags (which is
why they always say "This Side Down".
Ditto for some microwave frozen dinner entres.
Actually, that stuff (called "reluctor") doesn't _reflect_ the
microwaves - aluminum
foil does that admirably (I saw a photo shoot in an early microwave
oven cookbook -
they wrapped an ice cube in foil, set it in the oven next to a cup of
water, boiled the
water and the ice cube was virtually untouched.) But that stuff on the
bottom of the
popcorn pack is designed to _absorb_ the microwaves and turn them into
just plain
ol' heat. Sometimes you get those "hot pocket" thingies with reluctor
wrapped around
them to brown the crust.
I have a suspicion that the reluctor stuff is somehow related to
"radar-absorbent
materal" paint for stealth aircraft.
On Aug 26, 1:49 pm, jgy2001 <jgy2...@gmail.com> wrote:
What kind of simple material reflects microwave energy, such as
cellular and wifi signals?
...
The material that is embedded in some microwave popcorn bags (which is
why they always say "This Side Down".
Ditto for some microwave frozen dinner entres.
Actually, that stuff (called "reluctor") doesn't _reflect_ the
microwaves - aluminum
foil does that admirably (I saw a photo shoot in an early microwave
oven cookbook -
they wrapped an ice cube in foil, set it in the oven next to a cup of
water, boiled the
water and the ice cube was virtually untouched.) But that stuff on the
bottom of the
popcorn pack is designed to _absorb_ the microwaves and turn them into
just plain
ol' heat. Sometimes you get those "hot pocket" thingies with reluctor
wrapped around
them to brown the crust.
I have a suspicion that the reluctor stuff is somehow related to
"radar-absorbent
materal" paint for stealth aircraft.
---
Interesting.
http://en.wikipedia.org/wiki/Susceptor
---
JF
John Fields
Guest
Guest
Fri Aug 27, 2010 12:02 pm
On Thu, 26 Aug 2010 13:54:23 -0700 (PDT), Rich Grise on Google groups
<richardgrise_at_yahoo.com> wrote:
Quote:
On Aug 26, 12:30 pm, John Fields <jfie...@austininstruments.com
wrote:
On Thu, 26 Aug 2010 12:14:57 -0700, John Larkin
On Thu, 26 Aug 2010 12:11:53 -0700 (PDT), mpm <mpmill...@aol.com
On Aug 26, 1:49 pm, jgy2001 <jgy2...@gmail.com> wrote:
What kind of simple material reflects microwave energy, such as
cellular and wifi signals?
Anything metallic.
The material that is embedded in some microwave popcorn bags (which is
why they always say "This Side Down".
Ditto for some microwave frozen dinner entres.
Those things are designed to absorb, not reflect.
I disagree.
AFAIK, "Those things" are designed to reflect the RF into the food, in
order to heat the food, instead of heating the packaging and causing
the heat generated there to heat the food by conduction.
No, John, they're designed _exactly_ to heat the packaging (hence the
"this side down" admonition) and cause the heat generated there to
heat
the food by conduction, thus popping the corn on the bottom or
browning
the crust of a hot pocket thingie.
wrote:
On Thu, 26 Aug 2010 12:14:57 -0700, John Larkin
On Thu, 26 Aug 2010 12:11:53 -0700 (PDT), mpm <mpmill...@aol.com
On Aug 26, 1:49 pm, jgy2001 <jgy2...@gmail.com> wrote:
What kind of simple material reflects microwave energy, such as
cellular and wifi signals?
Anything metallic.
The material that is embedded in some microwave popcorn bags (which is
why they always say "This Side Down".
Ditto for some microwave frozen dinner entres.
Those things are designed to absorb, not reflect.
I disagree.
AFAIK, "Those things" are designed to reflect the RF into the food, in
order to heat the food, instead of heating the packaging and causing
the heat generated there to heat the food by conduction.
No, John, they're designed _exactly_ to heat the packaging (hence the
"this side down" admonition) and cause the heat generated there to
heat
the food by conduction, thus popping the corn on the bottom or
browning
the crust of a hot pocket thingie.
---
Interesting.
http://en.wikipedia.org/wiki/Susceptor
---
JF
Tim Williams
Guest
Guest
Fri Aug 27, 2010 1:56 pm
"John Fields" <jfields_at_austininstruments.com> wrote in message
news:cp6f76hn57hhan51h0kk0ge9mt54cb26m8_at_4ax.com...
Quote:
Graphite crucibles are absolutely beautiful for induction melting,
especially of materials that don't normally work well, like copper and
silver (which are too conductive and reflect most of the energy) or
insulators (like if you wanted to do glass, or synthesize diamonds, etc.).
It also has a nearly flat tempco, whereas metals change by more than an
order of magnitude before they melt. (Not to mention steel's additional
hysteresis losses at low temperature.)
Tim
--
Deep Friar: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms
Tim Wescott
Guest
Guest
Fri Aug 27, 2010 3:45 pm
On 08/26/2010 11:00 PM, David Eather wrote:
Quote:
On 27/08/2010 7:57 AM, Tim Wescott wrote:
On 08/26/2010 02:07 PM, David Eather wrote:
On 27/08/2010 5:08 AM, Tim Wescott wrote:
On 08/26/2010 11:49 AM, jgy2001 wrote:
What kind of simple material reflects microwave energy, such as
cellular and wifi signals?
I am thinking simple laminated material, such as film, or tape or
plastic sheets?
Can I embed simple film with some kind of simple metal to reflect
microwave signals?
Metal, or just about anything that's metalized. Aluminized mylar would
certainly count as a "simple film", and is somewhat conformal if you
don't mind cussing a bit.
If you can't find it anywhere else find a hobby shop that caters to
model airplane builders and ask for metallic Monocoat, or check out the
hobby websites (Tower Hobbies is good).
The "Emergency Space Blankets" beloved by rescue and emergency services
are aluminized mylar and cost something like one or two dollars per
square yard.
Of course! Why didn't I think of that?
(please don't answer).
I have lots of time, but little money on hand.
On 08/26/2010 02:07 PM, David Eather wrote:
On 27/08/2010 5:08 AM, Tim Wescott wrote:
On 08/26/2010 11:49 AM, jgy2001 wrote:
What kind of simple material reflects microwave energy, such as
cellular and wifi signals?
I am thinking simple laminated material, such as film, or tape or
plastic sheets?
Can I embed simple film with some kind of simple metal to reflect
microwave signals?
Metal, or just about anything that's metalized. Aluminized mylar would
certainly count as a "simple film", and is somewhat conformal if you
don't mind cussing a bit.
If you can't find it anywhere else find a hobby shop that caters to
model airplane builders and ask for metallic Monocoat, or check out the
hobby websites (Tower Hobbies is good).
The "Emergency Space Blankets" beloved by rescue and emergency services
are aluminized mylar and cost something like one or two dollars per
square yard.
Of course! Why didn't I think of that?
(please don't answer).
I have lots of time, but little money on hand.
You could make a great close-to-parabolic reflector with one of those
things just by sticking it to a round air tight frame and pulling a
vacuum. In fact, even if the frame weren't perfectly round it'd
probably still be an OK reflector.
The downside would be that you'd need to maintain the vacuum, but hey --
nothing in life is perfect.
--
Tim Wescott
Wescott Design Services
http://www.wescottdesign.com
Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" was written for you.
See details at http://www.wescottdesign.com/actfes/actfes.html
GregS
Guest
Guest
Fri Aug 27, 2010 4:36 pm
In article <9L6dncdJ1pQVSuvRnZ2dnUVZ_j-dnZ2d_at_giganews.com>, David Eather <eather_at_tpg.com.au> wrote:
Quote:
On 27/08/2010 5:08 AM, Tim Wescott wrote:
On 08/26/2010 11:49 AM, jgy2001 wrote:
What kind of simple material reflects microwave energy, such as
cellular and wifi signals?
I am thinking simple laminated material, such as film, or tape or
plastic sheets?
Can I embed simple film with some kind of simple metal to reflect
microwave signals?
Metal, or just about anything that's metalized. Aluminized mylar would
certainly count as a "simple film", and is somewhat conformal if you
don't mind cussing a bit.
If you can't find it anywhere else find a hobby shop that caters to
model airplane builders and ask for metallic Monocoat, or check out the
hobby websites (Tower Hobbies is good).
The "Emergency Space Blankets" beloved by rescue and emergency services
are aluminized mylar and cost something like one or two dollars per
square yard.
On 08/26/2010 11:49 AM, jgy2001 wrote:
What kind of simple material reflects microwave energy, such as
cellular and wifi signals?
I am thinking simple laminated material, such as film, or tape or
plastic sheets?
Can I embed simple film with some kind of simple metal to reflect
microwave signals?
Metal, or just about anything that's metalized. Aluminized mylar would
certainly count as a "simple film", and is somewhat conformal if you
don't mind cussing a bit.
If you can't find it anywhere else find a hobby shop that caters to
model airplane builders and ask for metallic Monocoat, or check out the
hobby websites (Tower Hobbies is good).
The "Emergency Space Blankets" beloved by rescue and emergency services
are aluminized mylar and cost something like one or two dollars per
square yard.
When Hostess used to put HoHo's in foil, it made a electrical storm inside
the microwave. I guess the foil could not take the current.
greg
Quote:
You can also get aluminum backed duct tape (you _don't_ want 'regular'
silver-colored duct tape -- you want the stuff that looks like aluminum
foil).
Or you could make a form, spray 3M 77 contact cement on it, and apply
aluminum foil.
Come to think of it, even something like silver paint might -- although
if it did it'd probably scatter quite a bit.
silver-colored duct tape -- you want the stuff that looks like aluminum
foil).
Or you could make a form, spray 3M 77 contact cement on it, and apply
aluminum foil.
Come to think of it, even something like silver paint might -- although
if it did it'd probably scatter quite a bit.
Jim Yanik
Guest
Guest
Fri Aug 27, 2010 4:41 pm
zekfrivo_at_zekfrivolous.com (GregS) wrote in
news:i58ltj$q9h$1_at_usenet01.srv.cis.pitt.edu:
Quote:
When Hostess used to put HoHo's in foil, it made a electrical storm
inside the microwave. I guess the foil could not take the current.
greg
no,you get standing waves and the voltage causes arcing,at sharp points.
the metalization acts as an antenna.
--
Jim Yanik
jyanik
at
localnet
dot com
Jan Panteltje
Guest
Guest
Fri Aug 27, 2010 6:26 pm
On Aug 27, 4:45 pm, Tim Wescott <t...@seemywebsite.com> wrote:
Quote:
On 08/26/2010 11:00 PM, David Eather wrote:
You could make a great close-to-parabolic reflector with one of those
things just by sticking it to a round air tight frame and pulling a
vacuum. In fact, even if the frame weren't perfectly round it'd
probably still be an OK reflector.
The downside would be that you'd need to maintain the vacuum, but hey --
nothing in life is perfect.
You could make a great close-to-parabolic reflector with one of those
things just by sticking it to a round air tight frame and pulling a
vacuum. In fact, even if the frame weren't perfectly round it'd
probably still be an OK reflector.
The downside would be that you'd need to maintain the vacuum, but hey --
nothing in life is perfect.
Or you could take a big tank full of mercury,
and slowly rotate it so the centrifugal force makes a parabolic shape,
allowing you to dynamically adjust the focus.
It has some drawbacks, but maybe you could sell it as 'green',
and they would not notice
L. Larry
Guest
Guest
Fri Aug 27, 2010 8:25 pm
Thank you for all your responses.
I am interested to learn the material that reflects microwave energy,
cellular and wifi signals, and these specific wavelengths?
I also interested to learn what is best and low cost to collect
cellular and wifi specific wavelength signals?
mpm
Guest
Guest
Fri Aug 27, 2010 9:02 pm
On Aug 27, 10:36 am, zekfr...@zekfrivolous.com (GregS) wrote:
Quote:
In article <9L6dncdJ1pQVSuvRnZ2dnUVZ_j-dn...@giganews.com>, David Eather <eat...@tpg.com.au> wrote:
On 27/08/2010 5:08 AM, Tim Wescott wrote:
On 08/26/2010 11:49 AM, jgy2001 wrote:
What kind of simple material reflects microwave energy, such as
cellular and wifi signals?
I am thinking simple laminated material, such as film, or tape or
plastic sheets?
Can I embed simple film with some kind of simple metal to reflect
microwave signals?
Metal, or just about anything that's metalized. Aluminized mylar would
certainly count as a "simple film", and is somewhat conformal if you
don't mind cussing a bit.
If you can't find it anywhere else find a hobby shop that caters to
model airplane builders and ask for metallic Monocoat, or check out the
hobby websites (Tower Hobbies is good).
The "Emergency Space Blankets" beloved by rescue and emergency services
are aluminized mylar and cost something like one or two dollars per
square yard.
When Hostess used to put HoHo's in foil, it made a electrical storm inside
the microwave. I guess the foil could not take the current.
greg
You can also get aluminum backed duct tape (you _don't_ want 'regular'
silver-colored duct tape -- you want the stuff that looks like aluminum
foil).
Or you could make a form, spray 3M 77 contact cement on it, and apply
aluminum foil.
Come to think of it, even something like silver paint might -- although
if it did it'd probably scatter quite a bit.- Hide quoted text -
- Show quoted text -- Hide quoted text -
- Show quoted text -
On 27/08/2010 5:08 AM, Tim Wescott wrote:
On 08/26/2010 11:49 AM, jgy2001 wrote:
What kind of simple material reflects microwave energy, such as
cellular and wifi signals?
I am thinking simple laminated material, such as film, or tape or
plastic sheets?
Can I embed simple film with some kind of simple metal to reflect
microwave signals?
Metal, or just about anything that's metalized. Aluminized mylar would
certainly count as a "simple film", and is somewhat conformal if you
don't mind cussing a bit.
If you can't find it anywhere else find a hobby shop that caters to
model airplane builders and ask for metallic Monocoat, or check out the
hobby websites (Tower Hobbies is good).
The "Emergency Space Blankets" beloved by rescue and emergency services
are aluminized mylar and cost something like one or two dollars per
square yard.
When Hostess used to put HoHo's in foil, it made a electrical storm inside
the microwave. I guess the foil could not take the current.
greg
You can also get aluminum backed duct tape (you _don't_ want 'regular'
silver-colored duct tape -- you want the stuff that looks like aluminum
foil).
Or you could make a form, spray 3M 77 contact cement on it, and apply
aluminum foil.
Come to think of it, even something like silver paint might -- although
if it did it'd probably scatter quite a bit.- Hide quoted text -
- Show quoted text -- Hide quoted text -
- Show quoted text -
Mental note to self: Greg puts Ho-Ho's in microwaves.
mpm
Guest
Guest
Fri Aug 27, 2010 9:08 pm
On Aug 27, 12:25 pm, "L. Larry" <larry.py...@gmail.com> wrote:
Quote:
Thank you for all your responses.
I am interested to learn the material that reflects microwave energy,
cellular and wifi signals, and these specific wavelengths?
I also interested to learn what is best and low cost to collect
cellular and wifi specific wavelength signals?
I am interested to learn the material that reflects microwave energy,
cellular and wifi signals, and these specific wavelengths?
I also interested to learn what is best and low cost to collect
cellular and wifi specific wavelength signals?
Low cost (for collecting) would be an antenna.
High cost (for reflecting) might be something like this:
Link: http://en.wikipedia.org/wiki/File:Signalreflectors.JPG
Near Salt Lake City, UT.
Up close, you can see they have little patterns cut into them to
better reflect certain wavelengths.
They use these as passive repeaters (no electronics whatsoever) to get
around mountainous terrain and other obstructions.
Sometimes you'll see them on old microwave relay towers (antennas on
the ground, passive reflector panels at altitude on a tower)
You wouldn't think they'd work, but they actually work quite well.
I recall in the early days of the space race, they launched a metal
spehere and bounced radio waves off it while it was in orbit.
Pretty much the same concept here.
-mpm
David Eather
Guest
Guest
Fri Aug 27, 2010 10:34 pm
On 27/08/2010 4:00 PM, David Eather wrote:
Quote:
On 27/08/2010 7:57 AM, Tim Wescott wrote:
On 08/26/2010 02:07 PM, David Eather wrote:
On 27/08/2010 5:08 AM, Tim Wescott wrote:
On 08/26/2010 11:49 AM, jgy2001 wrote:
What kind of simple material reflects microwave energy, such as
cellular and wifi signals?
I am thinking simple laminated material, such as film, or tape or
plastic sheets?
Can I embed simple film with some kind of simple metal to reflect
microwave signals?
Metal, or just about anything that's metalized. Aluminized mylar would
certainly count as a "simple film", and is somewhat conformal if you
don't mind cussing a bit.
If you can't find it anywhere else find a hobby shop that caters to
model airplane builders and ask for metallic Monocoat, or check out the
hobby websites (Tower Hobbies is good).
The "Emergency Space Blankets" beloved by rescue and emergency services
are aluminized mylar and cost something like one or two dollars per
square yard.
Of course! Why didn't I think of that?
(please don't answer).
I have lots of time, but little money on hand.
Oh, and I have 2 of them on my desk because I am assembling a
On 08/26/2010 02:07 PM, David Eather wrote:
On 27/08/2010 5:08 AM, Tim Wescott wrote:
On 08/26/2010 11:49 AM, jgy2001 wrote:
What kind of simple material reflects microwave energy, such as
cellular and wifi signals?
I am thinking simple laminated material, such as film, or tape or
plastic sheets?
Can I embed simple film with some kind of simple metal to reflect
microwave signals?
Metal, or just about anything that's metalized. Aluminized mylar would
certainly count as a "simple film", and is somewhat conformal if you
don't mind cussing a bit.
If you can't find it anywhere else find a hobby shop that caters to
model airplane builders and ask for metallic Monocoat, or check out the
hobby websites (Tower Hobbies is good).
The "Emergency Space Blankets" beloved by rescue and emergency services
are aluminized mylar and cost something like one or two dollars per
square yard.
Of course! Why didn't I think of that?
(please don't answer).
I have lots of time, but little money on hand.
Oh, and I have 2 of them on my desk because I am assembling a
"bug-out" bag
elektroda.net NewsGroups Forum Index - Electronics Design - what material reflects microwave?
