Hi

So I have invested in a TEM cell to be able to do relative EMC measurements

https://www.batronix.com/shop/measurement/tem-cells/TBTC2.html

I would like to have it shielded so I get rid of those signals from FM
and other radio emitters

I have looked at shield bag, intended for that:

https://www.tekbox.com/product/TBSB_Shielded-Bags_Manual.pdf

But it is about 500 USD, so I would like to do it cheaper

I have bought this metal reel, intending to build a cage and wrap it
with it along with aluminium tape for the edges

https://www.bauhaus.dk/icopal-dampspaerre-polykraft-24x1-25-m

Any better ideas?

Regards

Klaus

On Tue, 24 Aug 2021 16:58:27 +0200, Klaus Vestergaard Kragelund
<klauskvik@hotmail.com> wrote:

>Hi
>
>So I have invested in a TEM cell to be able to do relative EMC measurements
>
>https://www.batronix.com/shop/measurement/tem-cells/TBTC2.html

Do you plan to self-certify for CE? Testing radiated or suceptability
or both?

>
>I would like to have it shielded so I get rid of those signals from FM
>and other radio emitters
>
>I have looked at shield bag, intended for that:
>
>https://www.tekbox.com/product/TBSB_Shielded-Bags_Manual.pdf
>
>But it is about 500 USD, so I would like to do it cheaper
>
>I have bought this metal reel, intending to build a cage and wrap it
>with it along with aluminium tape for the edges
>
>https://www.bauhaus.dk/icopal-dampspaerre-polykraft-24x1-25-m
>
>Any better ideas?
>
>Regards
>
>Klaus
>
>

Personally, I'd take it to the mountains and work open-field.

You could get a big cardboard box and line it with aluminum foil,
inside and out.

But a small shielded bag or box will have giant cavity resonances...
lots of them.

--

Father Brown's figure remained quite dark and still;
but in that instant he had lost his head. His head was
always most valuable when he had lost it.

tirsdag den 24. august 2021 kl. 16.58.35 UTC+2 skrev Klaus Kragelund:
> Hi
>
> So I have invested in a TEM cell to be able to do relative EMC measurements
>
> https://www.batronix.com/shop/measurement/tem-cells/TBTC2.html
>
> I would like to have it shielded so I get rid of those signals from FM
> and other radio emitters
>
> I have looked at shield bag, intended for that:
>
> https://www.tekbox.com/product/TBSB_Shielded-Bags_Manual.pdf
>
> But it is about 500 USD, so I would like to do it cheaper
>
> I have bought this metal reel, intending to build a cage and wrap it
> with it along with aluminium tape for the edges
>
> https://www.bauhaus.dk/icopal-dampspaerre-polykraft-24x1-25-m

stick an Ohmmeter on it, can you actually connector to the metalization?
I think the tape would also need to have conductive glue

>
> Any better ideas?

I'd check ebay et.al. for condutive fabric

On Tue, 24 Aug 2021 08:33:35 -0700, jlarkin@highlandsniptechnology.com
wrote:

>On Tue, 24 Aug 2021 16:58:27 +0200, Klaus Vestergaard Kragelund
><klauskvik@hotmail.com> wrote:
>
>>Hi
>>
>>So I have invested in a TEM cell to be able to do relative EMC measurements
>>
>>https://www.batronix.com/shop/measurement/tem-cells/TBTC2.html
>
>
>Do you plan to self-certify for CE? Testing radiated or suceptability
>or both?
>
>>
>>I would like to have it shielded so I get rid of those signals from FM
>>and other radio emitters
>>
>>I have looked at shield bag, intended for that:
>>
>>https://www.tekbox.com/product/TBSB_Shielded-Bags_Manual.pdf
>>
>>But it is about 500 USD, so I would like to do it cheaper
>>
>>I have bought this metal reel, intending to build a cage and wrap it
>>with it along with aluminium tape for the edges
>>
>>https://www.bauhaus.dk/icopal-dampspaerre-polykraft-24x1-25-m
>>
>>Any better ideas?
>>
>>Regards
>>
>>Klaus
>>
>>
>
>Personally, I'd take it to the mountains and work open-field.
>
>You could get a big cardboard box and line it with aluminum foil,
>inside and out.
>
>But a small shielded bag or box will have giant cavity resonances...
>lots of them.

Or build a box out of copperclad FR4 with soldered joints.

You could build the TEM cell that way too.

--

Father Brown's figure remained quite dark and still;
but in that instant he had lost his head. His head was
always most valuable when he had lost it.

On a sunny day (Tue, 24 Aug 2021 16:58:27 +0200) it happened Klaus Vestergaard
Kragelund <klauskvik@hotmail.com> wrote in <sg31ej$lsc$1@gioia.aioe.org>:

>Hi
>
>So I have invested in a TEM cell to be able to do relative EMC measurements
>
>https://www.batronix.com/shop/measurement/tem-cells/TBTC2.html
>
>I would like to have it shielded so I get rid of those signals from FM
>and other radio emitters
>
>I have looked at shield bag, intended for that:
>
>https://www.tekbox.com/product/TBSB_Shielded-Bags_Manual.pdf
>
>But it is about 500 USD, so I would like to do it cheaper
>
>I have bought this metal reel, intending to build a cage and wrap it
>with it along with aluminium tape for the edges
>
>https://www.bauhaus.dk/icopal-dampspaerre-polykraft-24x1-25-m
>
>Any better ideas?
>
>Regards
>
>Klaus

How about a big cardboard box covered with alu foil?
10$ or so...
You can make the opening doors as simple or complicated as you want
and use what's left of the alu foil for hats.

On Tuesday, August 24, 2021 at 3:41:02 PM UTC, jla...@highlandsniptechnology.com wrote:
> On Tue, 24 Aug 2021 08:33:35 -0700, jla...@highlandsniptechnology.com
> wrote:
> >On Tue, 24 Aug 2021 16:58:27 +0200, Klaus Vestergaard Kragelund
> ><klau...@hotmail.com> wrote:
> >
> >>Hi
> >>
> >>So I have invested in a TEM cell to be able to do relative EMC measurements
> >>
> >>https://www.batronix.com/shop/measurement/tem-cells/TBTC2.html
> >
> >
> >Do you plan to self-certify for CE? Testing radiated or suceptability
> >or both?
> >
> >>
> >>I would like to have it shielded so I get rid of those signals from FM
> >>and other radio emitters
> >>
> >>I have looked at shield bag, intended for that:
> >>
> >>https://www.tekbox.com/product/TBSB_Shielded-Bags_Manual.pdf
> >>
> >>But it is about 500 USD, so I would like to do it cheaper
> >>
> >>I have bought this metal reel, intending to build a cage and wrap it
> >>with it along with aluminium tape for the edges
> >>
> >>https://www.bauhaus.dk/icopal-dampspaerre-polykraft-24x1-25-m
> >>
> >>Any better ideas?
> >>
> >>Regards
> >>
> >>Klaus
> >>
> >>
> >
> >Personally, I'd take it to the mountains and work open-field.
> >
> >You could get a big cardboard box and line it with aluminum foil,
> >inside and out.
> >
> >But a small shielded bag or box will have giant cavity resonances...
> >lots of them.
> Or build a box out of copperclad FR4 with soldered joints.
>
> You could build the TEM cell that way too.
> --
>
> Father Brown's figure remained quite dark and still;
> but in that instant he had lost his head. His head was
> always most valuable when he had lost it.

Hello Klaus,
A walk-in RF chamber would be the most convenient, I think, though its a
serious investment usually found at commercial test labs or universities
I don't suppose you have any friends or fellow IEEE members who would
lend you access for the time you need?
We have a chamber at our facility, in New York, that's often idle.
Before we built that my RF testing colleagues used a large trunk-sized
metal boxes. The connection inlet/outlet was itself a smaller box attached
and joined to the outside of the big box.

At your local home center store take a look around, e.g. some HVAC
ducting (galvanized tin), metal shears, sheet metal screws, ...?
The box will need 100% seal i..e. high conductivity all around, and at
the edges. The trick at the joined edges is to overlap the folds.
To allow you to repeatedly open & close the box, a "piano hinge"
could be employed with one sheet to form the door. You can use quick-
release snap fasteners to hold the door tight during measurements.

Cheers, RS

On Tuesday, August 24, 2021 at 4:35:39 PM UTC, Rich S wrote:
> On Tuesday, August 24, 2021 at 3:41:02 PM UTC, jla...@highlandsniptechnology.com wrote:
> > On Tue, 24 Aug 2021 08:33:35 -0700, jla...@highlandsniptechnology.com
> > wrote:
> > >On Tue, 24 Aug 2021 16:58:27 +0200, Klaus Vestergaard Kragelund
> > ><klau...@hotmail.com> wrote:
> > >
> > >>Hi
> > >>
> > >>So I have invested in a TEM cell to be able to do relative EMC measurements
> > >>
> > >>https://www.batronix.com/shop/measurement/tem-cells/TBTC2.html
> > >
> > >
> > >Do you plan to self-certify for CE? Testing radiated or suceptability
> > >or both?
> > >
> > >>
> > >>I would like to have it shielded so I get rid of those signals from FM
> > >>and other radio emitters
> > >>
> > >>I have looked at shield bag, intended for that:
> > >>
> > >>https://www.tekbox.com/product/TBSB_Shielded-Bags_Manual.pdf
> > >>
> > >>But it is about 500 USD, so I would like to do it cheaper
> > >>
> > >>I have bought this metal reel, intending to build a cage and wrap it
> > >>with it along with aluminium tape for the edges
> > >>
> > >>https://www.bauhaus.dk/icopal-dampspaerre-polykraft-24x1-25-m
> > >>
> > >>Any better ideas?
> > >>
> > >>Regards
> > >>
> > >>Klaus
> > >>
> > >>
> > >
> > >Personally, I'd take it to the mountains and work open-field.
> > >
> > >You could get a big cardboard box and line it with aluminum foil,
> > >inside and out.
> > >
> > >But a small shielded bag or box will have giant cavity resonances...
> > >lots of them.
> > Or build a box out of copperclad FR4 with soldered joints.
> >
> > You could build the TEM cell that way too.
> > --
> >
> > Father Brown's figure remained quite dark and still;
> > but in that instant he had lost his head. His head was
> > always most valuable when he had lost it.
> Hello Klaus,
> A walk-in RF chamber would be the most convenient, I think, though its a
> serious investment usually found at commercial test labs or universities
> I don't suppose you have any friends or fellow IEEE members who would
> lend you access for the time you need?
> We have a chamber at our facility, in New York, that's often idle.
> Before we built that my RF testing colleagues used a large trunk-sized
> metal boxes. The connection inlet/outlet was itself a smaller box attached
> and joined to the outside of the big box.
>
> At your local home center store take a look around, e.g. some HVAC
> ducting (galvanized tin), metal shears, sheet metal screws, ...?
> The box will need 100% seal i..e. high conductivity all around, and at
> the edges. The trick at the joined edges is to overlap the folds.
> To allow you to repeatedly open & close the box, a "piano hinge"
> could be employed with one sheet to form the door. You can use quick-
> release snap fasteners to hold the door tight during measurements.
>
> Cheers, RS

Untreated, the boxwill be RF "echo chamber" with all sorts of resonances
at different frequencies at different locations. Either, you (a) treat the inside,
or (b) 'characterize' the behavior and subtract it out post-analysis.
Treating the inside is easier in concept, e.g., energy-absorptive wedges.
My collegues (also on a budget) used blocks of various sizes of conductive
black foam (that ICs used to be stored/shipped in).
Characterize+Post-analyis correction is tricky; it might only work up to 10GHz
or so; your DUT setup has to consistent; and your analysis system has to provide
a "curve correction" feature, etc.

On Tue, 24 Aug 2021 08:40:52 -0700, jlarkin@highlandsniptechnology.com
wrote:

>On Tue, 24 Aug 2021 08:33:35 -0700, jlarkin@highlandsniptechnology.com
>wrote:
>
>>On Tue, 24 Aug 2021 16:58:27 +0200, Klaus Vestergaard Kragelund
>><klauskvik@hotmail.com> wrote:
>>
>>>Hi
>>>
>>>So I have invested in a TEM cell to be able to do relative EMC measurements
>>>
>>>https://www.batronix.com/shop/measurement/tem-cells/TBTC2.html
>>
>>
>>Do you plan to self-certify for CE? Testing radiated or suceptability
>>or both?
>>
>>>
>>>I would like to have it shielded so I get rid of those signals from FM
>>>and other radio emitters
>>>
>>>I have looked at shield bag, intended for that:
>>>
>>>https://www.tekbox.com/product/TBSB_Shielded-Bags_Manual.pdf
>>>
>>>But it is about 500 USD, so I would like to do it cheaper
>>>
>>>I have bought this metal reel, intending to build a cage and wrap it
>>>with it along with aluminium tape for the edges
>>>
>>>https://www.bauhaus.dk/icopal-dampspaerre-polykraft-24x1-25-m
>>>
>>>Any better ideas?
>>>
>>>Regards
>>>
>>>Klaus
>>>
>>>
>>
>>Personally, I'd take it to the mountains and work open-field.
>>
>>You could get a big cardboard box and line it with aluminum foil,
>>inside and out.
>>
>>But a small shielded bag or box will have giant cavity resonances...
>>lots of them.
>
>
>Or build a box out of copperclad FR4 with soldered joints.
>
>You could build the TEM cell that way too.

Goofy idea: make a box out of multilayer PC boards, tiled maybe. Outer
layers are ground planes. Inners are a maze of fractal antennas and
termination resistors. If not totally absorbing inside, that would at
least kill the cavity Q.

Next, build in the transmit/receive connectors.

Would that work? There are planar antennas on PC boards.

--

Father Brown's figure remained quite dark and still;
but in that instant he had lost his head. His head was
always most valuable when he had lost it.

On Tue, 24 Aug 2021 16:21:55 GMT, Jan Panteltje
<pNaonStpealmtje@yahoo.com> wrote:

>On a sunny day (Tue, 24 Aug 2021 16:58:27 +0200) it happened Klaus Vestergaard
>Kragelund <klauskvik@hotmail.com> wrote in <sg31ej$lsc$1@gioia.aioe.org>:
>
>>Hi
>>
>>So I have invested in a TEM cell to be able to do relative EMC measurements
>>
>>https://www.batronix.com/shop/measurement/tem-cells/TBTC2.html
>>
>>I would like to have it shielded so I get rid of those signals from FM
>>and other radio emitters
>>
>>I have looked at shield bag, intended for that:
>>
>>https://www.tekbox.com/product/TBSB_Shielded-Bags_Manual.pdf
>>
>>But it is about 500 USD, so I would like to do it cheaper
>>
>>I have bought this metal reel, intending to build a cage and wrap it
>>with it along with aluminium tape for the edges
>>
>>https://www.bauhaus.dk/icopal-dampspaerre-polykraft-24x1-25-m
>>
>>Any better ideas?
>>
>>Regards
>>
>>Klaus
>
>How about a big cardboard box covered with alu foil?
>10$ or so...
>You can make the opening doors as simple or complicated as you want
>and use what's left of the alu foil for hats.
>

No, No! Use the leftovers for baking chicken in foil, a tasty asian
dish.

--

Father Brown's figure remained quite dark and still;
but in that instant he had lost his head. His head was
always most valuable when he had lost it.

On Tue, 24 Aug 2021 16:58:27 +0200, Klaus Vestergaard Kragelund
<klauskvik@hotmail.com> wrote:

>Hi
>
>So I have invested in a TEM cell to be able to do relative EMC measurements
>
>https://www.batronix.com/shop/measurement/tem-cells/TBTC2.html
>
>I would like to have it shielded so I get rid of those signals from FM
>and other radio emitters
>
>I have looked at shield bag, intended for that:
>
>https://www.tekbox.com/product/TBSB_Shielded-Bags_Manual.pdf
>
>But it is about 500 USD, so I would like to do it cheaper
>
>I have bought this metal reel, intending to build a cage and wrap it
>with it along with aluminium tape for the edges
>
>https://www.bauhaus.dk/icopal-dampspaerre-polykraft-24x1-25-m
>
>Any better ideas?

You are basically trying to fabricate a faraday cage. For table-top
use, one can fabricate a cage using copper window screen mesh bent
over a thicker solid copper wire frame, with mesh soldered to the
frame using soft (tin-lead) solder - just as for making copper
gutters. Build a flange along the long side with a matching
framed-mesh closing plate, with some means to clamp plate to flange.

There will also be an I/O plate studded with feed-through connectors.

And, to break up cavity resonances, make it strange-looking - nothing
parallel to anything - a crooked little house

One can also lay sheets of RF absorbing foam or sheet on the floor to
further suppress cavity resonances.

Joe Gwinn

On 24/08/2021 17.33, jlarkin@highlandsniptechnology.com wrote:
> On Tue, 24 Aug 2021 16:58:27 +0200, Klaus Vestergaard Kragelund
> <klauskvik@hotmail.com> wrote:
>
>> Hi
>>
>> So I have invested in a TEM cell to be able to do relative EMC measurements
>>
>> https://www.batronix.com/shop/measurement/tem-cells/TBTC2.html
>
>
> Do you plan to self-certify for CE? Testing radiated or suceptability
> or both?
>

I have access to a calibrated 3m semi anechoic chamber, and will be
testing both emission and immunity. The reason I write relative
measurements is that the TEM results cannot be used directly for
evaluating 3m room measurements

>>
>> I would like to have it shielded so I get rid of those signals from FM
>> and other radio emitters
>>
>> I have looked at shield bag, intended for that:
>>
>> https://www.tekbox.com/product/TBSB_Shielded-Bags_Manual.pdf
>>
>> But it is about 500 USD, so I would like to do it cheaper
>>
>> I have bought this metal reel, intending to build a cage and wrap it
>> with it along with aluminium tape for the edges
>>
>> https://www.bauhaus.dk/icopal-dampspaerre-polykraft-24x1-25-m
>>
>> Any better ideas?
>>
>> Regards
>>
>> Klaus
>>
>>
>
> Personally, I'd take it to the mountains and work open-field.
>

Yeah would be best, but no way to do that. I cannot spend the time and
move equipment back and forth is a no go

> You could get a big cardboard box and line it with aluminum foil,
> inside and out.

Yes, that is actually what I am doing. Next step is to create some walls
in full room height with aluminium foil (for VHF) and metal cage on top
(for LF). Also add EMC springs to openings and wire feedthrough
filtering. But again, next step, when I get time ;-)
>
> But a small shielded bag or box will have giant cavity resonances...
> lots of them.
>
>

Yes. Some test standards actually use this intentional, with reflectors
instead of absorbers

On 24/08/2021 17.40, jlarkin@highlandsniptechnology.com wrote:
> On Tue, 24 Aug 2021 08:33:35 -0700, jlarkin@highlandsniptechnology.com
> wrote:
>
>> On Tue, 24 Aug 2021 16:58:27 +0200, Klaus Vestergaard Kragelund
>> <klauskvik@hotmail.com> wrote:
>>
>>> Hi
>>>
>>> So I have invested in a TEM cell to be able to do relative EMC measurements
>>>
>>> https://www.batronix.com/shop/measurement/tem-cells/TBTC2.html
>>
>>
>> Do you plan to self-certify for CE? Testing radiated or suceptability
>> or both?
>>
>>>
>>> I would like to have it shielded so I get rid of those signals from FM
>>> and other radio emitters
>>>
>>> I have looked at shield bag, intended for that:
>>>
>>> https://www.tekbox.com/product/TBSB_Shielded-Bags_Manual.pdf
>>>
>>> But it is about 500 USD, so I would like to do it cheaper
>>>
>>> I have bought this metal reel, intending to build a cage and wrap it
>>> with it along with aluminium tape for the edges
>>>
>>> https://www.bauhaus.dk/icopal-dampspaerre-polykraft-24x1-25-m
>>>
>>> Any better ideas?
>>>
>>> Regards
>>>
>>> Klaus
>>>
>>>
>>
>> Personally, I'd take it to the mountains and work open-field.
>>
>> You could get a big cardboard box and line it with aluminum foil,
>> inside and out.
>>
>> But a small shielded bag or box will have giant cavity resonances...
>> lots of them.
>
>
> Or build a box out of copperclad FR4 with soldered joints.
>
> You could build the TEM cell that way too.
>
Yes, was my first thought. But spending the time on the box, I can just
buy it since that will mean I can bill hours on other stuff

On 24/08/2021 18.35, Rich S wrote:
> On Tuesday, August 24, 2021 at 3:41:02 PM UTC, jla...@highlandsniptechnology.com wrote:
>> On Tue, 24 Aug 2021 08:33:35 -0700, jla...@highlandsniptechnology.com
>> wrote:
>>> On Tue, 24 Aug 2021 16:58:27 +0200, Klaus Vestergaard Kragelund
>>> <klau...@hotmail.com> wrote:
>>>
>>>> Hi
>>>>
>>>> So I have invested in a TEM cell to be able to do relative EMC measurements
>>>>
>>>> https://www.batronix.com/shop/measurement/tem-cells/TBTC2.html
>>>
>>>
>>> Do you plan to self-certify for CE? Testing radiated or suceptability
>>> or both?
>>>
>>>>
>>>> I would like to have it shielded so I get rid of those signals from FM
>>>> and other radio emitters
>>>>
>>>> I have looked at shield bag, intended for that:
>>>>
>>>> https://www.tekbox.com/product/TBSB_Shielded-Bags_Manual.pdf
>>>>
>>>> But it is about 500 USD, so I would like to do it cheaper
>>>>
>>>> I have bought this metal reel, intending to build a cage and wrap it
>>>> with it along with aluminium tape for the edges
>>>>
>>>> https://www.bauhaus.dk/icopal-dampspaerre-polykraft-24x1-25-m
>>>>
>>>> Any better ideas?
>>>>
>>>> Regards
>>>>
>>>> Klaus
>>>>
>>>>
>>>
>>> Personally, I'd take it to the mountains and work open-field.
>>>
>>> You could get a big cardboard box and line it with aluminum foil,
>>> inside and out.
>>>
>>> But a small shielded bag or box will have giant cavity resonances...
>>> lots of them.
>> Or build a box out of copperclad FR4 with soldered joints.
>>
>> You could build the TEM cell that way too.
>> --
>>
>> Father Brown's figure remained quite dark and still;
>> but in that instant he had lost his head. His head was
>> always most valuable when he had lost it.
>
>
> Hello Klaus,
> A walk-in RF chamber would be the most convenient, I think, though its a
> serious investment usually found at commercial test labs or universities
> I don't suppose you have any friends or fellow IEEE members who would
> lend you access for the time you need?
> We have a chamber at our facility, in New York, that's often idle.
> Before we built that my RF testing colleagues used a large trunk-sized
> metal boxes. The connection inlet/outlet was itself a smaller box attached
> and joined to the outside of the big box.

I have access to a chamber, but want my own setup so I can use it when I
want and don't need to drive to do testing

>
> At your local home center store take a look around, e.g. some HVAC
> ducting (galvanized tin), metal shears, sheet metal screws, ...?
> The box will need 100% seal i..e. high conductivity all around, and at
> the edges. The trick at the joined edges is to overlap the folds.

Yes, I need overlap, no apertures allowed. I will measure the
attenuation of the foil, since I may need double layer to get sufficient
attenuation. Measurement is simple done with a antenna and emitter
reference, then placing the wall in between

> To allow you to repeatedly open & close the box, a "piano hinge"
> could be employed with one sheet to form the door. You can use quick-
> release snap fasteners to hold the door tight during measurements.
>

On 24/08/2021 18.51, Rich S wrote:
> On Tuesday, August 24, 2021 at 4:35:39 PM UTC, Rich S wrote:
>> On Tuesday, August 24, 2021 at 3:41:02 PM UTC, jla...@highlandsniptechnology.com wrote:
>>> On Tue, 24 Aug 2021 08:33:35 -0700, jla...@highlandsniptechnology.com
>>> wrote:
>>>> On Tue, 24 Aug 2021 16:58:27 +0200, Klaus Vestergaard Kragelund
>>>> <klau...@hotmail.com> wrote:
>>>>
>>>>> Hi
>>>>>
>>>>> So I have invested in a TEM cell to be able to do relative EMC measurements
>>>>>
>>>>> https://www.batronix.com/shop/measurement/tem-cells/TBTC2.html
>>>>
>>>>
>>>> Do you plan to self-certify for CE? Testing radiated or suceptability
>>>> or both?
>>>>
>>>>>
>>>>> I would like to have it shielded so I get rid of those signals from FM
>>>>> and other radio emitters
>>>>>
>>>>> I have looked at shield bag, intended for that:
>>>>>
>>>>> https://www.tekbox.com/product/TBSB_Shielded-Bags_Manual.pdf
>>>>>
>>>>> But it is about 500 USD, so I would like to do it cheaper
>>>>>
>>>>> I have bought this metal reel, intending to build a cage and wrap it
>>>>> with it along with aluminium tape for the edges
>>>>>
>>>>> https://www.bauhaus.dk/icopal-dampspaerre-polykraft-24x1-25-m
>>>>>
>>>>> Any better ideas?
>>>>>
>>>>> Regards
>>>>>
>>>>> Klaus
>>>>>
>>>>>
>>>>
>>>> Personally, I'd take it to the mountains and work open-field.
>>>>
>>>> You could get a big cardboard box and line it with aluminum foil,
>>>> inside and out.
>>>>
>>>> But a small shielded bag or box will have giant cavity resonances...
>>>> lots of them.
>>> Or build a box out of copperclad FR4 with soldered joints.
>>>
>>> You could build the TEM cell that way too.
>>> --
>>>
>>> Father Brown's figure remained quite dark and still;
>>> but in that instant he had lost his head. His head was
>>> always most valuable when he had lost it.
>> Hello Klaus,
>> A walk-in RF chamber would be the most convenient, I think, though its a
>> serious investment usually found at commercial test labs or universities
>> I don't suppose you have any friends or fellow IEEE members who would
>> lend you access for the time you need?
>> We have a chamber at our facility, in New York, that's often idle.
>> Before we built that my RF testing colleagues used a large trunk-sized
>> metal boxes. The connection inlet/outlet was itself a smaller box attached
>> and joined to the outside of the big box.
>>
>> At your local home center store take a look around, e.g. some HVAC
>> ducting (galvanized tin), metal shears, sheet metal screws, ...?
>> The box will need 100% seal i..e. high conductivity all around, and at
>> the edges. The trick at the joined edges is to overlap the folds.
>> To allow you to repeatedly open & close the box, a "piano hinge"
>> could be employed with one sheet to form the door. You can use quick-
>> release snap fasteners to hold the door tight during measurements.
>>
>> Cheers, RS
>
> Untreated, the boxwill be RF "echo chamber" with all sorts of resonances
> at different frequencies at different locations. Either, you (a) treat the inside,
> or (b) 'characterize' the behavior and subtract it out post-analysis.
> Treating the inside is easier in concept, e.g., energy-absorptive wedges.
> My collegues (also on a budget) used blocks of various sizes of conductive
> black foam (that ICs used to be stored/shipped in).
> Characterize+Post-analyis correction is tricky; it might only work up to 10GHz
> or so; your DUT setup has to consistent; and your analysis system has to provide
> a "curve correction" feature, etc.
>

For the large chamber I will get reflections. For the small chamber,
that is really just put on top of the TEM. The TEM is in it self a
transmission line, an open one, so the small chamber is just to remove
ambient noise, so reflections inside wont matter much

I am on a budget, so will be on a lookout for the absorbtion black foam.

>

On 24/08/2021 17.35, Lasse Langwadt Christensen wrote:
> tirsdag den 24. august 2021 kl. 16.58.35 UTC+2 skrev Klaus Kragelund:
>> Hi
>>
>> So I have invested in a TEM cell to be able to do relative EMC measurements
>>
>> https://www.batronix.com/shop/measurement/tem-cells/TBTC2.html
>>
>> I would like to have it shielded so I get rid of those signals from FM
>> and other radio emitters
>>
>> I have looked at shield bag, intended for that:
>>
>> https://www.tekbox.com/product/TBSB_Shielded-Bags_Manual.pdf
>>
>> But it is about 500 USD, so I would like to do it cheaper
>>
>> I have bought this metal reel, intending to build a cage and wrap it
>> with it along with aluminium tape for the edges
>>
>> https://www.bauhaus.dk/icopal-dampspaerre-polykraft-24x1-25-m
>
> stick an Ohmmeter on it, can you actually connector to the metalization?
> I think the tape would also need to have conductive glue
>

Yes, the one I ordered may not be good. Working from home so I took a
chance. Next step is a you say to go to the hardware store and probe the
different types they have to be sure I can access the metal foil

>>
>> Any better ideas?
>
> I'd check ebay et.al. for condutive fabric
>
>
Will do :-)

On 24/08/2021 18.21, Jan Panteltje wrote:
> On a sunny day (Tue, 24 Aug 2021 16:58:27 +0200) it happened Klaus Vestergaard
> Kragelund <klauskvik@hotmail.com> wrote in <sg31ej$lsc$1@gioia.aioe.org>:
>
>> Hi
>>
>> So I have invested in a TEM cell to be able to do relative EMC measurements
>>
>> https://www.batronix.com/shop/measurement/tem-cells/TBTC2.html
>>
>> I would like to have it shielded so I get rid of those signals from FM
>> and other radio emitters
>>
>> I have looked at shield bag, intended for that:
>>
>> https://www.tekbox.com/product/TBSB_Shielded-Bags_Manual.pdf
>>
>> But it is about 500 USD, so I would like to do it cheaper
>>
>> I have bought this metal reel, intending to build a cage and wrap it
>> with it along with aluminium tape for the edges
>>
>> https://www.bauhaus.dk/icopal-dampspaerre-polykraft-24x1-25-m
>>
>> Any better ideas?
>>
>> Regards
>>
>> Klaus
>
> How about a big cardboard box covered with alu foil?
> 10$ or so...
> You can make the opening doors as simple or complicated as you want
> and use what's left of the alu foil for hats.
>
>
Yes, that was my first idea also. Kitchen alu foil may just do the trick ;-)

On 24/08/2021 19.20, Joe Gwinn wrote:
> On Tue, 24 Aug 2021 16:58:27 +0200, Klaus Vestergaard Kragelund
> <klauskvik@hotmail.com> wrote:
>
>> Hi
>>
>> So I have invested in a TEM cell to be able to do relative EMC measurements
>>
>> https://www.batronix.com/shop/measurement/tem-cells/TBTC2.html
>>
>> I would like to have it shielded so I get rid of those signals from FM
>> and other radio emitters
>>
>> I have looked at shield bag, intended for that:
>>
>> https://www.tekbox.com/product/TBSB_Shielded-Bags_Manual.pdf
>>
>> But it is about 500 USD, so I would like to do it cheaper
>>
>> I have bought this metal reel, intending to build a cage and wrap it
>> with it along with aluminium tape for the edges
>>
>> https://www.bauhaus.dk/icopal-dampspaerre-polykraft-24x1-25-m
>>
>> Any better ideas?
>
> You are basically trying to fabricate a faraday cage. For table-top
> use, one can fabricate a cage using copper window screen mesh bent
> over a thicker solid copper wire frame, with mesh soldered to the
> frame using soft (tin-lead) solder - just as for making copper
> gutters. Build a flange along the long side with a matching
> framed-mesh closing plate, with some means to clamp plate to flange.
>
> There will also be an I/O plate studded with feed-through connectors.
>
> And, to break up cavity resonances, make it strange-looking - nothing
> parallel to anything - a crooked little house
>
Very nice, that is a good idea, I was thinking a square box, but you are
thinking "outside the box" ;-)

> One can also lay sheets of RF absorbing foam or sheet on the floor to
> further suppress cavity resonances.
>
> Joe Gwinn
>

On Tuesday, 24 August 2021 at 23:08:36 UTC+1, Klaus Kragelund wrote:
> On 24/08/2021 19.20, Joe Gwinn wrote:
> > On Tue, 24 Aug 2021 16:58:27 +0200, Klaus Vestergaard Kragelund
> > <klau...@hotmail.com> wrote:
> >
> >> Hi
> >>
> >> So I have invested in a TEM cell to be able to do relative EMC measurements
> >>
> >> https://www.batronix.com/shop/measurement/tem-cells/TBTC2.html
> >>
> >> I would like to have it shielded so I get rid of those signals from FM
> >> and other radio emitters
> >>
> >> I have looked at shield bag, intended for that:
> >>
> >> https://www.tekbox.com/product/TBSB_Shielded-Bags_Manual.pdf
> >>
> >> But it is about 500 USD, so I would like to do it cheaper
> >>
> >> I have bought this metal reel, intending to build a cage and wrap it
> >> with it along with aluminium tape for the edges
> >>
> >> https://www.bauhaus.dk/icopal-dampspaerre-polykraft-24x1-25-m
> >>
> >> Any better ideas?
> >
> > You are basically trying to fabricate a faraday cage. For table-top
> > use, one can fabricate a cage using copper window screen mesh bent
> > over a thicker solid copper wire frame, with mesh soldered to the
> > frame using soft (tin-lead) solder - just as for making copper
> > gutters. Build a flange along the long side with a matching
> > framed-mesh closing plate, with some means to clamp plate to flange.
> >
> > There will also be an I/O plate studded with feed-through connectors.
> >
> > And, to break up cavity resonances, make it strange-looking - nothing
> > parallel to anything - a crooked little house
> >
> Very nice, that is a good idea, I was thinking a square box, but you are
> thinking "outside the box" ;-)
> > One can also lay sheets of RF absorbing foam or sheet on the floor to
> > further suppress cavity resonances.
> >
> > Joe Gwinn
> >
You can improve the flatness of the frequency response in a reflective
box by having a large metal-bladed fan inside it. As it spins the resonances
change in frequency. A bit of averaging then gets you a much flatter
response than before.

John

onsdag den 25. august 2021 kl. 00.35.54 UTC+2 skrev John Walliker:
> On Tuesday, 24 August 2021 at 23:08:36 UTC+1, Klaus Kragelund wrote:
> > On 24/08/2021 19.20, Joe Gwinn wrote:
> > > On Tue, 24 Aug 2021 16:58:27 +0200, Klaus Vestergaard Kragelund
> > > <klau...@hotmail.com> wrote:
> > >
> > >> Hi
> > >>
> > >> So I have invested in a TEM cell to be able to do relative EMC measurements
> > >>
> > >> https://www.batronix.com/shop/measurement/tem-cells/TBTC2.html
> > >>
> > >> I would like to have it shielded so I get rid of those signals from FM
> > >> and other radio emitters
> > >>
> > >> I have looked at shield bag, intended for that:
> > >>
> > >> https://www.tekbox.com/product/TBSB_Shielded-Bags_Manual.pdf
> > >>
> > >> But it is about 500 USD, so I would like to do it cheaper
> > >>
> > >> I have bought this metal reel, intending to build a cage and wrap it
> > >> with it along with aluminium tape for the edges
> > >>
> > >> https://www.bauhaus.dk/icopal-dampspaerre-polykraft-24x1-25-m
> > >>
> > >> Any better ideas?
> > >
> > > You are basically trying to fabricate a faraday cage. For table-top
> > > use, one can fabricate a cage using copper window screen mesh bent
> > > over a thicker solid copper wire frame, with mesh soldered to the
> > > frame using soft (tin-lead) solder - just as for making copper
> > > gutters. Build a flange along the long side with a matching
> > > framed-mesh closing plate, with some means to clamp plate to flange.
> > >
> > > There will also be an I/O plate studded with feed-through connectors.
> > >
> > > And, to break up cavity resonances, make it strange-looking - nothing
> > > parallel to anything - a crooked little house
> > >
> > Very nice, that is a good idea, I was thinking a square box, but you are
> > thinking "outside the box" ;-)
> > > One can also lay sheets of RF absorbing foam or sheet on the floor to
> > > further suppress cavity resonances.
> > >
> > > Joe Gwinn
> > >
> You can improve the flatness of the frequency response in a reflective
> box by having a large metal-bladed fan inside it. As it spins the resonances
> change in frequency. A bit of averaging then gets you a much flatter
> response than before.

some microwave ovens do that instead of having a rotating platter to get even heating

On 25/08/2021 00.35, John Walliker wrote:
> On Tuesday, 24 August 2021 at 23:08:36 UTC+1, Klaus Kragelund wrote:
>> On 24/08/2021 19.20, Joe Gwinn wrote:
>>> On Tue, 24 Aug 2021 16:58:27 +0200, Klaus Vestergaard Kragelund
>>> <klau...@hotmail.com> wrote:
>>>
>>>> Hi
>>>>
>>>> So I have invested in a TEM cell to be able to do relative EMC measurements
>>>>
>>>> https://www.batronix.com/shop/measurement/tem-cells/TBTC2.html
>>>>
>>>> I would like to have it shielded so I get rid of those signals from FM
>>>> and other radio emitters
>>>>
>>>> I have looked at shield bag, intended for that:
>>>>
>>>> https://www.tekbox.com/product/TBSB_Shielded-Bags_Manual.pdf
>>>>
>>>> But it is about 500 USD, so I would like to do it cheaper
>>>>
>>>> I have bought this metal reel, intending to build a cage and wrap it
>>>> with it along with aluminium tape for the edges
>>>>
>>>> https://www.bauhaus.dk/icopal-dampspaerre-polykraft-24x1-25-m
>>>>
>>>> Any better ideas?
>>>
>>> You are basically trying to fabricate a faraday cage. For table-top
>>> use, one can fabricate a cage using copper window screen mesh bent
>>> over a thicker solid copper wire frame, with mesh soldered to the
>>> frame using soft (tin-lead) solder - just as for making copper
>>> gutters. Build a flange along the long side with a matching
>>> framed-mesh closing plate, with some means to clamp plate to flange.
>>>
>>> There will also be an I/O plate studded with feed-through connectors.
>>>
>>> And, to break up cavity resonances, make it strange-looking - nothing
>>> parallel to anything - a crooked little house
>>>
>> Very nice, that is a good idea, I was thinking a square box, but you are
>> thinking "outside the box" ;-)
>>> One can also lay sheets of RF absorbing foam or sheet on the floor to
>>> further suppress cavity resonances.
>>>
>>> Joe Gwinn
>>>
> You can improve the flatness of the frequency response in a reflective
> box by having a large metal-bladed fan inside it. As it spins the resonances
> change in frequency. A bit of averaging then gets you a much flatter
> response than before.
>

Very nice idea. I guess it needs to be very large though

tirsdag den 24. august 2021 kl. 16.58.35 UTC+2 skrev Klaus Kragelund:
> Hi
>
> So I have invested in a TEM cell to be able to do relative EMC measurements
>
> https://www.batronix.com/shop/measurement/tem-cells/TBTC2.html
>
> I would like to have it shielded so I get rid of those signals from FM
> and other radio emitters
>
> I have looked at shield bag, intended for that:
>
> https://www.tekbox.com/product/TBSB_Shielded-Bags_Manual.pdf
>
> But it is about 500 USD, so I would like to do it cheaper
>
> I have bought this metal reel, intending to build a cage and wrap it
> with it along with aluminium tape for the edges
>
> https://www.bauhaus.dk/icopal-dampspaerre-polykraft-24x1-25-m
>
> Any better ideas?
>

mesh size small enough?

https://insektorama.dk/koeb/insektnet-i-rustfrit-staal-maskestoerrelse-3-mm/

Am 24.08.21 um 16:58 schrieb Klaus Vestergaard Kragelund:
> Hi
>
> So I have invested in a TEM cell to be able to do relative EMC measurements
>
> https://www.batronix.com/shop/measurement/tem-cells/TBTC2.html
>
> I would like to have it shielded so I get rid of those signals from FM
> and other radio emitters
>
> I have looked at shield bag, intended for that:
>
> https://www.tekbox.com/product/TBSB_Shielded-Bags_Manual.pdf
>
> But it is about 500 USD, so I would like to do it cheaper
>
> I have bought this metal reel, intending to build a cage and wrap it
> with it along with aluminium tape for the edges
>
> https://www.bauhaus.dk/icopal-dampspaerre-polykraft-24x1-25-m

Someone I knew from univ in a previous life but lost out of sight
over the decades had also built such a cell and IIRC he ended up
with lots of ferrite tiles (AVX ??).

Lessons learned resulted in

<
http://www.euro-emc-service.com/view/data/5388/PDF%20Website/Publikationen%20BSP/PUBL_eurotem.pdf
>

(more on the site)

Running such a lab is a cut-throat business. Customers tend not
to come back when they do not get the results they want, no matter
what the DUT looks like. And the "good" customers have a lab of
their own and need only someone accredited to sign and carry the
risks. No one can make a living out of this and even trying to
provide a solution is perceived as messing around with a
perfectly finished product.

There once was an experiment by the authorities in .de where
they sent around a carefully designed piece of sh*t and even some
accredited labs were off by 20 dB. That created quite an uproar.

cheers, Gerhard

On 25/08/2021 05.56, Gerhard Hoffmann wrote:
> Am 24.08.21 um 16:58 schrieb Klaus Vestergaard Kragelund:
>> Hi
>>
>> So I have invested in a TEM cell to be able to do relative EMC
>> measurements
>>
>> https://www.batronix.com/shop/measurement/tem-cells/TBTC2.html
>>
>> I would like to have it shielded so I get rid of those signals from FM
>> and other radio emitters
>>
>> I have looked at shield bag, intended for that:
>>
>> https://www.tekbox.com/product/TBSB_Shielded-Bags_Manual.pdf
>>
>> But it is about 500 USD, so I would like to do it cheaper
>>
>> I have bought this metal reel, intending to build a cage and wrap it
>> with it along with aluminium tape for the edges
>>
>> https://www.bauhaus.dk/icopal-dampspaerre-polykraft-24x1-25-m
>
> Someone I knew from univ in a previous life but lost out of sight
> over the decades had also built such a cell and IIRC he ended up
> with lots of ferrite tiles (AVX ??).
>
> Lessons learned resulted in
>
> <
> http://www.euro-emc-service.com/view/data/5388/PDF%20Website/Publikationen%20BSP/PUBL_eurotem.pdf
>      >
>
> (more on the site)
>
> Running such a lab is a cut-throat business. Customers tend not
> to come back when they do not get the results they want, no matter
> what the DUT looks like. And the "good" customers have a lab of
> their own and need only someone accredited to sign and carry the
> risks. No one can make a living out of this and even trying to
> provide a solution is perceived as messing around with a
> perfectly finished product.
>

Yes, running a lab is not my thing. I just need it for my own measurements

> There once was an experiment by the authorities in .de where
> they sent around a carefully designed piece of sh*t and even some
> accredited labs were off by 20 dB. That created quite an uproar.
>
So the labs was not calibrated regulary? I thought that is a requirement

On Wednesday, 25 August 2021 at 10:07:57 UTC+1, Klaus Kragelund wrote:
> On 25/08/2021 05.56, Gerhard Hoffmann wrote:
> > Am 24.08.21 um 16:58 schrieb Klaus Vestergaard Kragelund:
> >> Hi
> >>
> >> So I have invested in a TEM cell to be able to do relative EMC
> >> measurements
> >>
> >> https://www.batronix.com/shop/measurement/tem-cells/TBTC2.html
> >>
> >> I would like to have it shielded so I get rid of those signals from FM
> >> and other radio emitters
> >>
> >> I have looked at shield bag, intended for that:
> >>
> >> https://www.tekbox.com/product/TBSB_Shielded-Bags_Manual.pdf
> >>
> >> But it is about 500 USD, so I would like to do it cheaper
> >>
> >> I have bought this metal reel, intending to build a cage and wrap it
> >> with it along with aluminium tape for the edges
> >>
> >> https://www.bauhaus.dk/icopal-dampspaerre-polykraft-24x1-25-m
> >
> > Someone I knew from univ in a previous life but lost out of sight
> > over the decades had also built such a cell and IIRC he ended up
> > with lots of ferrite tiles (AVX ??).
> >
> > Lessons learned resulted in
> >
> > <
> > http://www.euro-emc-service.com/view/data/5388/PDF%20Website/Publikationen%20BSP/PUBL_eurotem.pdf
> > >
> >
> > (more on the site)
> >
> > Running such a lab is a cut-throat business. Customers tend not
> > to come back when they do not get the results they want, no matter
> > what the DUT looks like. And the "good" customers have a lab of
> > their own and need only someone accredited to sign and carry the
> > risks. No one can make a living out of this and even trying to
> > provide a solution is perceived as messing around with a
> > perfectly finished product.
> >
> Yes, running a lab is not my thing. I just need it for my own measurements
> > There once was an experiment by the authorities in .de where
> > they sent around a carefully designed piece of sh*t and even some
> > accredited labs were off by 20 dB. That created quite an uproar.
> >
> So the labs was not calibrated regulary? I thought that is a requirement

I have done many emissions measurements free field in the garden at
frequencies up to 1GHz and then later had them verified by a test lab
(usually Intertek).
It is unusual to get a difference of more than 2 or 3 dB.

John

Klaus Vestergaard Kragelund wrote:
> On 24/08/2021 19.20, Joe Gwinn wrote:
>> On Tue, 24 Aug 2021 16:58:27 +0200, Klaus Vestergaard Kragelund
>> <klauskvik@hotmail.com> wrote:
>>
>>> Hi
>>>
>>> So I have invested in a TEM cell to be able to do relative EMC
>>> measurements
>>>
>>> https://www.batronix.com/shop/measurement/tem-cells/TBTC2.html
>>>
>>> I would like to have it shielded so I get rid of those signals from FM
>>> and other radio emitters
>>>
>>> I have looked at shield bag, intended for that:
>>>
>>> https://www.tekbox.com/product/TBSB_Shielded-Bags_Manual.pdf
>>>
>>> But it is about 500 USD, so I would like to do it cheaper
>>>
>>> I have bought this metal reel, intending to build a cage and wrap it
>>> with it along with aluminium tape for the edges
>>>
>>> https://www.bauhaus.dk/icopal-dampspaerre-polykraft-24x1-25-m
>>>
>>> Any better ideas?
>>
>> You are basically trying to fabricate a faraday cage.  For table-top
>> use, one can fabricate a cage using copper window screen mesh bent
>> over a thicker solid copper wire frame, with mesh soldered to the
>> frame using soft (tin-lead) solder - just as for making copper
>> gutters.  Build a flange along the long side with a matching
>> framed-mesh closing plate, with some means to clamp plate to flange.
>>
>> There will also be an I/O plate studded with feed-through connectors.
>>
>> And, to break up cavity resonances, make it strange-looking - nothing
>> parallel to anything - a crooked little house
>>
> Very nice, that is a good idea, I was thinking a square box, but you are
> thinking "outside the box" ;-)

It'll still resonate, you just won't know where in advance.
At least it's easy to calculate the eigenmodes of a rectangular box.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com