• Mirror as ground plane

    From legg@21:1/5 to All on Wed Nov 27 08:53:41 2024
    Anyone had experience using metalization on glass (mirror)
    as a ground plane or shield?

    Any data on conductivity etc?

    RL

    --- SoupGate-Win32 v1.05
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  • From Martin Brown@21:1/5 to legg on Wed Nov 27 14:18:04 2024
    On 27/11/2024 13:53, legg wrote:

    Anyone had experience using metalization on glass (mirror)
    as a ground plane or shield?

    Any data on conductivity etc?

    At what frequency? Your problem will be mainly making a good physical
    contact with the mirror. Aluminium has pretty good conductivity but an
    annoying oxide coat. Gold sputtered mirrors would be easier to solder.

    Indium is used for ground planes that you can see though. Radio
    astronomers tend to use glass with fine copper mesh embedded in it to
    keep the control room electronics from drowning out natural signals.

    --
    Martin Brown

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  • From Bill Sloman@21:1/5 to legg on Thu Nov 28 01:22:13 2024
    On 28/11/2024 12:53 am, legg wrote:

    Anyone had experience using metalization on glass (mirror)
    as a ground plane or shield?

    None.

    Any data on conductivity etc?

    It's difficult to get much below 100ohm per square with metal layers.
    You can't get thinner than one atom thick, and while in theory the microcrystals of metal can offer a circuitious path, you are laying them
    down at random.

    I made the mistake of asking for vacuum deposited layer of carbon with
    highish resistance, and got told off by the people who did it.

    We ended up using a thick film layer of some very resistive metal
    oxide-based thick-film ink - about a micron of it.

    --
    Bill Sloman, Sydney

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  • From Phil Hobbs@21:1/5 to legg on Wed Nov 27 14:24:20 2024
    legg <legg@nospam.magma.ca> wrote:

    Anyone had experience using metalization on glass (mirror)
    as a ground plane or shield?

    Any data on conductivity etc?

    RL


    The best quality second-surface mirrors are coated with silver, followed by copper plating and a coat of paint. Those should be pretty good if you can
    get wires on them.

    Poorer ones have aluminum coatings around 2-3 nm thick and no plating.

    Cheers

    Phil Hobbs



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

    --- SoupGate-Win32 v1.05
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  • From legg@21:1/5 to All on Wed Nov 27 11:13:21 2024
    On Thu, 28 Nov 2024 01:22:13 +1100, Bill Sloman <bill.sloman@ieee.org>
    wrote:

    On 28/11/2024 12:53 am, legg wrote:

    Anyone had experience using metalization on glass (mirror)
    as a ground plane or shield?

    None.

    Any data on conductivity etc?

    It's difficult to get much below 100ohm per square with metal layers.
    You can't get thinner than one atom thick, and while in theory the >microcrystals of metal can offer a circuitious path, you are laying them
    down at random.

    I made the mistake of asking for vacuum deposited layer of carbon with >highish resistance, and got told off by the people who did it.

    We ended up using a thick film layer of some very resistive metal
    oxide-based thick-film ink - about a micron of it.


    Ron Wagner used ~dish soap once, to get high resistivity films
    on some electrostatic panels.

    You can imagine trying to get predictable or durable perforance
    that way . . . .

    RL

    --- SoupGate-Win32 v1.05
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  • From legg@21:1/5 to pcdhSpamMeSenseless@electrooptical. on Wed Nov 27 11:31:59 2024
    On Wed, 27 Nov 2024 14:24:20 -0000 (UTC), Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    legg <legg@nospam.magma.ca> wrote:

    Anyone had experience using metalization on glass (mirror)
    as a ground plane or shield?

    Any data on conductivity etc?

    RL


    The best quality second-surface mirrors are coated with silver, followed by >copper plating and a coat of paint. Those should be pretty good if you can >get wires on them.

    Poorer ones have aluminum coatings around 2-3 nm thick and no plating.

    Cheers

    Phil Hobbs

    I think pressure contact will be good enough, so long as its renewed
    regularly, maybe with a conductive grit.

    Will have to treat the isolated glass surface with something to
    reduce static, or stuff will start flying away at inconvenient
    times.

    RL

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  • From Joe Gwinn@21:1/5 to pcdhSpamMeSenseless@electrooptical. on Wed Nov 27 11:41:54 2024
    On Wed, 27 Nov 2024 14:24:20 -0000 (UTC), Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    legg <legg@nospam.magma.ca> wrote:

    Anyone had experience using metalization on glass (mirror)
    as a ground plane or shield?

    Any data on conductivity etc?

    RL


    The best quality second-surface mirrors are coated with silver, followed by >copper plating and a coat of paint. Those should be pretty good if you can >get wires on them.

    A classic way to connect to such things is conductive silver epoxy,
    probably to silver-plated copper wire. Not tin-plated for long-term
    use.

    .<https://www.masterbond.com/properties/silver-filled-electrically-conductive-adhesives>

    As for shielding effectiveness, the key question is the resistance of
    a square of the coating, connected only on opposite parallel sides.


    Poorer ones have aluminum coatings around 2-3 nm thick and no plating.

    Probably won't work, between high square resistance and oxide layer
    preventing reliable connection.

    Though people do use metallized Mylar film, with a long bare tinned
    copper ground wire in direct contact with the aluminum side, and in a
    cable this does work.

    Joe Gwinn

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  • From Phil Hobbs@21:1/5 to legg on Wed Nov 27 17:07:35 2024
    legg <legg@nospam.magma.ca> wrote:
    On Wed, 27 Nov 2024 14:24:20 -0000 (UTC), Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    legg <legg@nospam.magma.ca> wrote:

    Anyone had experience using metalization on glass (mirror)
    as a ground plane or shield?

    Any data on conductivity etc?

    RL


    The best quality second-surface mirrors are coated with silver, followed by >> copper plating and a coat of paint. Those should be pretty good if you can >> get wires on them.

    Poorer ones have aluminum coatings around 2-3 nm thick and no plating.

    Cheers

    Phil Hobbs

    I think pressure contact will be good enough, so long as its renewed regularly, maybe with a conductive grit.

    Will have to treat the isolated glass surface with something to
    reduce static, or stuff will start flying away at inconvenient
    times.

    RL


    Won’t work on an unplated film, of course. Indium solder applied with an ultrasonic iron is one approach—you need to avoid cracking the film, which will cause extreme flakiness.

    Cheers

    Phil Hobbs

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

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  • From Glen Walpert@21:1/5 to legg on Wed Nov 27 17:52:19 2024
    On Wed, 27 Nov 2024 11:31:59 -0500, legg wrote:

    On Wed, 27 Nov 2024 14:24:20 -0000 (UTC), Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    legg <legg@nospam.magma.ca> wrote:

    Anyone had experience using metalization on glass (mirror)
    as a ground plane or shield?

    Any data on conductivity etc?

    RL


    The best quality second-surface mirrors are coated with silver, followed
    by copper plating and a coat of paint. Those should be pretty good if
    you can get wires on them.

    Poorer ones have aluminum coatings around 2-3 nm thick and no plating.

    Cheers

    Phil Hobbs

    I think pressure contact will be good enough, so long as its renewed regularly, maybe with a conductive grit.

    If you use a conductive colloidal copper electrical joint compound such as Thomas & Betts Kopr-Shield or Burndy Penetrox E between your copper plated surface and a copper alloy spring contact the need to renew should be eliminated.

    This stuff is essential for reliable mechanical Cu-Cu connections in a corrosive environment.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Joe Gwinn@21:1/5 to jrwalliker@gmail.com on Wed Nov 27 13:37:01 2024
    On Wed, 27 Nov 2024 17:08:04 +0000, John R Walliker
    <jrwalliker@gmail.com> wrote:

    On 27/11/2024 16:41, Joe Gwinn wrote:
    On Wed, 27 Nov 2024 14:24:20 -0000 (UTC), Phil Hobbs
    <pcdhSpamMeSenseless@electrooptical.net> wrote:

    legg <legg@nospam.magma.ca> wrote:

    Anyone had experience using metalization on glass (mirror)
    as a ground plane or shield?

    Any data on conductivity etc?

    RL


    The best quality second-surface mirrors are coated with silver, followed by >>> copper plating and a coat of paint. Those should be pretty good if you can >>> get wires on them.

    A classic way to connect to such things is conductive silver epoxy,
    probably to silver-plated copper wire. Not tin-plated for long-term
    use.

    .<https://www.masterbond.com/properties/silver-filled-electrically-conductive-adhesives>

    As for shielding effectiveness, the key question is the resistance of
    a square of the coating, connected only on opposite parallel sides.


    Poorer ones have aluminum coatings around 2-3 nm thick and no plating.

    Probably won't work, between high square resistance and oxide layer
    preventing reliable connection.

    Though people do use metallized Mylar film, with a long bare tinned
    copper ground wire in direct contact with the aluminum side, and in a
    cable this does work.

    Joe Gwinn
    At high enough frequencies there is no need for direct connection.
    Adhesive copper tape stuck to the varnish film on the back of an
    ordinary mirror may provide enough capacitive coupling to make a
    good connection. It all depends on the proposed application, which
    we don't know.
    John

    Agreed,

    Joe

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  • From john larkin@21:1/5 to legg on Wed Nov 27 12:53:01 2024
    On Wed, 27 Nov 2024 08:53:41 -0500, legg <legg@nospam.magma.ca> wrote:


    Anyone had experience using metalization on glass (mirror)
    as a ground plane or shield?

    Any data on conductivity etc?

    RL

    Why use glass? Why not copperclad FR4?

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From legg@21:1/5 to All on Wed Nov 27 22:08:13 2024
    On Wed, 27 Nov 2024 12:53:01 -0800, john larkin <jl@glen--canyon.com>
    wrote:

    On Wed, 27 Nov 2024 08:53:41 -0500, legg <legg@nospam.magma.ca> wrote:


    Anyone had experience using metalization on glass (mirror)
    as a ground plane or shield?

    Any data on conductivity etc?

    RL

    Why use glass? Why not copperclad FR4?

    Rugged repeated use - subjected to fire and impact.

    Will be possibly burning FR4 in contact with it.

    A work surface.

    RL

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Liz Tuddenham@21:1/5 to John R Walliker on Thu Nov 28 11:15:01 2024
    John R Walliker <jrwalliker@gmail.com> wrote:

    On 27/11/2024 16:41, Joe Gwinn wrote:
    On Wed, 27 Nov 2024 14:24:20 -0000 (UTC), Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    legg <legg@nospam.magma.ca> wrote:

    Anyone had experience using metalization on glass (mirror)
    as a ground plane or shield?

    Any data on conductivity etc?

    RL


    The best quality second-surface mirrors are coated with silver, followed by
    copper plating and a coat of paint. Those should be pretty good if you can
    get wires on them.

    A classic way to connect to such things is conductive silver epoxy, probably to silver-plated copper wire. Not tin-plated for long-term
    use.

    .<https://www.masterbond.com/properties/silver-filled-electrically-condu ctive-adhesives>

    As for shielding effectiveness, the key question is the resistance of
    a square of the coating, connected only on opposite parallel sides.


    Poorer ones have aluminum coatings around 2-3 nm thick and no plating.

    Probably won't work, between high square resistance and oxide layer preventing reliable connection.

    Though people do use metallized Mylar film, with a long bare tinned
    copper ground wire in direct contact with the aluminum side, and in a
    cable this does work.

    Joe Gwinn
    At high enough frequencies there is no need for direct connection.
    Adhesive copper tape stuck to the varnish film on the back of an
    ordinary mirror may provide enough capacitive coupling to make a
    good connection.

    This can even work at highish audio frequencies:

    I was trying to trace some disconnected house wiring by feeding about
    50v of 1 Kc/s audio into the accessible end and following the signal capacitively with a high impedance probe connected to a tuned amplifier
    and headphones. The wires were in the space between the ceiling of the downstairs rooms and the floorboards of the upstairs rooms; it was
    easiest to trace them from below because there was a lot of furniture
    and other clutter in the upstairs rooms.

    The signal led towards an outer wall of the house which had had a garage
    built onto it. From inside the house, the wires appeared to be running
    along the wall in the garage , but there were no wires visible in the
    garage ... and from the garage, the signal appeared to be coming from
    inside the house.

    Then I realised that there was a large mirror inside the house on that
    wall and the signal was being capacitively coupled to the top edge of
    the mirror by wires that must have been at least a foot above it and
    separated by a plasterboard [drywall] ceiling. The whole mirror was re-radiating the signal.


    --
    ~ Liz Tuddenham ~
    (Remove the ".invalid"s and add ".co.uk" to reply)
    www.poppyrecords.co.uk

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From john larkin@21:1/5 to legg on Thu Nov 28 07:16:55 2024
    On Wed, 27 Nov 2024 22:08:13 -0500, legg <legg@nospam.magma.ca> wrote:

    On Wed, 27 Nov 2024 12:53:01 -0800, john larkin <jl@glen--canyon.com>
    wrote:

    On Wed, 27 Nov 2024 08:53:41 -0500, legg <legg@nospam.magma.ca> wrote:


    Anyone had experience using metalization on glass (mirror)
    as a ground plane or shield?

    Any data on conductivity etc?

    RL

    Why use glass? Why not copperclad FR4?

    Rugged repeated use - subjected to fire and impact.

    Will be possibly burning FR4 in contact with it.

    A work surface.

    RL

    Stainless steel is pretty conductive.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From john larkin@21:1/5 to Liz Tuddenham on Thu Nov 28 07:26:11 2024
    On Thu, 28 Nov 2024 11:15:01 +0000, liz@poppyrecords.invalid.invalid
    (Liz Tuddenham) wrote:

    John R Walliker <jrwalliker@gmail.com> wrote:

    On 27/11/2024 16:41, Joe Gwinn wrote:
    On Wed, 27 Nov 2024 14:24:20 -0000 (UTC), Phil Hobbs
    <pcdhSpamMeSenseless@electrooptical.net> wrote:

    legg <legg@nospam.magma.ca> wrote:

    Anyone had experience using metalization on glass (mirror)
    as a ground plane or shield?

    Any data on conductivity etc?

    RL


    The best quality second-surface mirrors are coated with silver, followed by
    copper plating and a coat of paint. Those should be pretty good if you can
    get wires on them.

    A classic way to connect to such things is conductive silver epoxy,
    probably to silver-plated copper wire. Not tin-plated for long-term
    use.

    .<https://www.masterbond.com/properties/silver-filled-electrically-condu >> > ctive-adhesives>

    As for shielding effectiveness, the key question is the resistance of
    a square of the coating, connected only on opposite parallel sides.


    Poorer ones have aluminum coatings around 2-3 nm thick and no plating.

    Probably won't work, between high square resistance and oxide layer
    preventing reliable connection.

    Though people do use metallized Mylar film, with a long bare tinned
    copper ground wire in direct contact with the aluminum side, and in a
    cable this does work.

    Joe Gwinn
    At high enough frequencies there is no need for direct connection.
    Adhesive copper tape stuck to the varnish film on the back of an
    ordinary mirror may provide enough capacitive coupling to make a
    good connection.

    This can even work at highish audio frequencies:

    I was trying to trace some disconnected house wiring by feeding about
    50v of 1 Kc/s audio into the accessible end and following the signal >capacitively with a high impedance probe connected to a tuned amplifier
    and headphones. The wires were in the space between the ceiling of the >downstairs rooms and the floorboards of the upstairs rooms; it was
    easiest to trace them from below because there was a lot of furniture
    and other clutter in the upstairs rooms.

    The signal led towards an outer wall of the house which had had a garage >built onto it. From inside the house, the wires appeared to be running
    along the wall in the garage , but there were no wires visible in the
    garage ... and from the garage, the signal appeared to be coming from
    inside the house.

    Then I realised that there was a large mirror inside the house on that
    wall and the signal was being capacitively coupled to the top edge of
    the mirror by wires that must have been at least a foot above it and >separated by a plasterboard [drywall] ceiling. The whole mirror was >re-radiating the signal.

    It's interesting to walk around and listen to ambient e and h fields,
    and light too.

    You can trace wires by listening to the 50/60 Hz fields, usually with
    lots of harmonics.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Liz Tuddenham@21:1/5 to john larkin on Thu Nov 28 15:47:11 2024
    john larkin <JL@gct.com> wrote:

    On Thu, 28 Nov 2024 11:15:01 +0000, liz@poppyrecords.invalid.invalid
    (Liz Tuddenham) wrote:

    John R Walliker <jrwalliker@gmail.com> wrote:

    On 27/11/2024 16:41, Joe Gwinn wrote:
    On Wed, 27 Nov 2024 14:24:20 -0000 (UTC), Phil Hobbs
    <pcdhSpamMeSenseless@electrooptical.net> wrote:

    legg <legg@nospam.magma.ca> wrote:

    Anyone had experience using metalization on glass (mirror)
    as a ground plane or shield?

    Any data on conductivity etc?

    RL

    The best quality second-surface mirrors are coated with silver,
    followed by >> copper plating and a coat of paint. Those should be
    pretty good if you can >> get wires on them. > > A classic way to
    connect to such things is conductive silver epoxy, > probably to
    silver-plated copper wire. Not tin-plated for long-term > use. > >
    .<https://www.masterbond.com/properties/silver-filled-electrically-cond
    u > ctive-adhesives> > > As for shielding effectiveness, the key
    question is the resistance of > a square of the coating, connected only
    on opposite parallel sides. > > >> Poorer ones have aluminum coatings
    around 2-3 nm thick and no plating. > > Probably won't work, between
    high square resistance and oxide layer > preventing reliable
    connection. > > Though people do use metallized Mylar film, with a long
    bare tinned > copper ground wire in direct contact with the aluminum
    side, and in a > cable this does work. > > Joe Gwinn At high enough
    frequencies there is no need for direct connection. Adhesive copper
    tape stuck to the varnish film on the back of an ordinary mirror may
    provide enough capacitive coupling to make a good connection.

    This can even work at highish audio frequencies:

    I was trying to trace some disconnected house wiring by feeding about
    50v of 1 Kc/s audio into the accessible end and following the signal >capacitively with a high impedance probe connected to a tuned amplifier
    and headphones. The wires were in the space between the ceiling of the >downstairs rooms and the floorboards of the upstairs rooms; it was
    easiest to trace them from below because there was a lot of furniture
    and other clutter in the upstairs rooms.

    The signal led towards an outer wall of the house which had had a garage >built onto it. From inside the house, the wires appeared to be running >along the wall in the garage , but there were no wires visible in the >garage ... and from the garage, the signal appeared to be coming from >inside the house.

    Then I realised that there was a large mirror inside the house on that
    wall and the signal was being capacitively coupled to the top edge of
    the mirror by wires that must have been at least a foot above it and >separated by a plasterboard [drywall] ceiling. The whole mirror was >re-radiating the signal.

    It's interesting to walk around and listen to ambient e and h fields,
    and light too.

    I once built an IR detector into the body of a little hand torch so that
    I could carry it unobtrusively around the site where I worked. The
    management hadn't told us they were installing surveillance equipment,
    but the IR illuminators for the hidden cameras showed up quite clearly.


    You can trace wires by listening to the 50/60 Hz fields, usually with
    lots of harmonics.

    Yes, if they are the only wires you are interested in; across open
    ground, for instance. In a house, when trying to trace a specific wire,
    you need some sort of identifying signal such as a bleeper. I also have
    an exceptionally noisy electric drill that can be used to mark a circuit
    (it was used in the construction of the Brabazon airliner and pre-dates effective suppression methods).

    It is easiest to track the magnetic field if you can get to both ends of
    the wire and make a complete circuit, but if the wire has been cut and
    you don't know where it goes, the electrostatic field is more traceable
    as long as there isn't a lot of earthed metal or damp material in the
    way. Sometimes there is enough capacitance to earth at the cut end of
    the cable that some highish frequency current can be driven down it and
    make electromagnetic detection possible.


    --
    ~ Liz Tuddenham ~
    (Remove the ".invalid"s and add ".co.uk" to reply)
    www.poppyrecords.co.uk

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From john larkin@21:1/5 to Liz Tuddenham on Thu Nov 28 11:29:04 2024
    On Thu, 28 Nov 2024 15:47:11 +0000, liz@poppyrecords.invalid.invalid
    (Liz Tuddenham) wrote:

    john larkin <JL@gct.com> wrote:

    On Thu, 28 Nov 2024 11:15:01 +0000, liz@poppyrecords.invalid.invalid
    (Liz Tuddenham) wrote:

    John R Walliker <jrwalliker@gmail.com> wrote:

    On 27/11/2024 16:41, Joe Gwinn wrote:
    On Wed, 27 Nov 2024 14:24:20 -0000 (UTC), Phil Hobbs
    <pcdhSpamMeSenseless@electrooptical.net> wrote:

    legg <legg@nospam.magma.ca> wrote:

    Anyone had experience using metalization on glass (mirror)
    as a ground plane or shield?

    Any data on conductivity etc?

    RL

    The best quality second-surface mirrors are coated with silver,
    followed by >> copper plating and a coat of paint. Those should be
    pretty good if you can >> get wires on them. > > A classic way to
    connect to such things is conductive silver epoxy, > probably to
    silver-plated copper wire. Not tin-plated for long-term > use. > >
    .<https://www.masterbond.com/properties/silver-filled-electrically-cond >> >> u > ctive-adhesives> > > As for shielding effectiveness, the key
    question is the resistance of > a square of the coating, connected only >> >> on opposite parallel sides. > > >> Poorer ones have aluminum coatings
    around 2-3 nm thick and no plating. > > Probably won't work, between
    high square resistance and oxide layer > preventing reliable
    connection. > > Though people do use metallized Mylar film, with a long >> >> bare tinned > copper ground wire in direct contact with the aluminum
    side, and in a > cable this does work. > > Joe Gwinn At high enough
    frequencies there is no need for direct connection. Adhesive copper
    tape stuck to the varnish film on the back of an ordinary mirror may
    provide enough capacitive coupling to make a good connection.

    This can even work at highish audio frequencies:

    I was trying to trace some disconnected house wiring by feeding about
    50v of 1 Kc/s audio into the accessible end and following the signal
    capacitively with a high impedance probe connected to a tuned amplifier
    and headphones. The wires were in the space between the ceiling of the
    downstairs rooms and the floorboards of the upstairs rooms; it was
    easiest to trace them from below because there was a lot of furniture
    and other clutter in the upstairs rooms.

    The signal led towards an outer wall of the house which had had a garage
    built onto it. From inside the house, the wires appeared to be running
    along the wall in the garage , but there were no wires visible in the
    garage ... and from the garage, the signal appeared to be coming from
    inside the house.

    Then I realised that there was a large mirror inside the house on that
    wall and the signal was being capacitively coupled to the top edge of
    the mirror by wires that must have been at least a foot above it and
    separated by a plasterboard [drywall] ceiling. The whole mirror was
    re-radiating the signal.

    It's interesting to walk around and listen to ambient e and h fields,
    and light too.

    I once built an IR detector into the body of a little hand torch so that
    I could carry it unobtrusively around the site where I worked. The >management hadn't told us they were installing surveillance equipment,
    but the IR illuminators for the hidden cameras showed up quite clearly.

    It wouldn't be hard to include a circuit that down-samples
    ultrasonics.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Bill Sloman@21:1/5 to john larkin on Fri Nov 29 15:40:11 2024
    On 29/11/2024 2:16 am, john larkin wrote:
    On Wed, 27 Nov 2024 22:08:13 -0500, legg <legg@nospam.magma.ca> wrote:

    On Wed, 27 Nov 2024 12:53:01 -0800, john larkin <jl@glen--canyon.com>
    wrote:

    On Wed, 27 Nov 2024 08:53:41 -0500, legg <legg@nospam.magma.ca> wrote:


    Anyone had experience using metalization on glass (mirror)
    as a ground plane or shield?

    Any data on conductivity etc?

    RL

    Why use glass? Why not copperclad FR4?

    Rugged repeated use - subjected to fire and impact.

    Will be possibly burning FR4 in contact with it.

    A work surface.

    RL

    Stainless steel is pretty conductive.

    But it's covered in a thin coherent layer of chromium oxide, which is
    pretty conductive, but to a degree that depends on the pH of the
    monolayer of water adsorbed on the surface. Some of my colleagues once
    wanted to use it for the electrodes in a conductivity meter and it
    messed up the accuracy for high-conductivity water (2% NaOH in the worst
    case - not exactly water as you want to meet it).

    --
    Bill Sloman, Sydney

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  • From legg@21:1/5 to john larkin on Fri Nov 29 08:46:25 2024
    On Thu, 28 Nov 2024 07:16:55 -0800, john larkin <JL@gct.com> wrote:

    On Wed, 27 Nov 2024 22:08:13 -0500, legg <legg@nospam.magma.ca> wrote:

    On Wed, 27 Nov 2024 12:53:01 -0800, john larkin <jl@glen--canyon.com> >>wrote:

    On Wed, 27 Nov 2024 08:53:41 -0500, legg <legg@nospam.magma.ca> wrote:


    Anyone had experience using metalization on glass (mirror)
    as a ground plane or shield?

    Any data on conductivity etc?

    RL

    Why use glass? Why not copperclad FR4?

    Rugged repeated use - subjected to fire and impact.

    Will be possibly burning FR4 in contact with it.

    A work surface.

    RL

    Stainless steel is pretty conductive.

    which glass ain't . . .

    Mind you, they're both just peachy to bend, drill, or to
    work with simple hand tools - luckily avoided here once
    sharp edges are tamed.

    The consideration only came up when the basic material
    showed up, free, begging for safe 'disposal'.

    Not sure if the idea might be useful to others, elsewhere.

    RL

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  • From john larkin@21:1/5 to legg on Fri Nov 29 07:59:08 2024
    On Fri, 29 Nov 2024 08:46:25 -0500, legg <legg@nospam.magma.ca> wrote:

    On Thu, 28 Nov 2024 07:16:55 -0800, john larkin <JL@gct.com> wrote:

    On Wed, 27 Nov 2024 22:08:13 -0500, legg <legg@nospam.magma.ca> wrote:

    On Wed, 27 Nov 2024 12:53:01 -0800, john larkin <jl@glen--canyon.com> >>>wrote:

    On Wed, 27 Nov 2024 08:53:41 -0500, legg <legg@nospam.magma.ca> wrote:


    Anyone had experience using metalization on glass (mirror)
    as a ground plane or shield?

    Any data on conductivity etc?

    RL

    Why use glass? Why not copperclad FR4?

    Rugged repeated use - subjected to fire and impact.

    Will be possibly burning FR4 in contact with it.

    A work surface.

    RL

    Stainless steel is pretty conductive.

    which glass ain't . . .

    Mind you, they're both just peachy to bend, drill, or to
    work with simple hand tools - luckily avoided here once
    sharp edges are tamed.

    The consideration only came up when the basic material
    showed up, free, begging for safe 'disposal'.

    Mirrors? We went on a garden tour and one guy had a tiny yard with
    mirrors on the fences. It looked huge, great fun. He served tea and
    cookies to the visitors.

    I'm not interested in plants like Mo is, but the garden tours are fun.
    One guy near the Presidio has a waterfall in his back yard, Lobos
    Creek.


    Not sure if the idea might be useful to others, elsewhere.

    RL

    I recall some sort of conductive glass, antistat level, but you
    probably don't have that.

    There are antistat sprays, which I think are mildly hygroscopic, for
    floors and such.

    --- SoupGate-Win32 v1.05
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  • From legg@21:1/5 to john larkin on Sat Nov 30 10:05:47 2024
    On Fri, 29 Nov 2024 07:59:08 -0800, john larkin <JL@gct.com> wrote:

    On Fri, 29 Nov 2024 08:46:25 -0500, legg <legg@nospam.magma.ca> wrote:

    On Thu, 28 Nov 2024 07:16:55 -0800, john larkin <JL@gct.com> wrote:

    On Wed, 27 Nov 2024 22:08:13 -0500, legg <legg@nospam.magma.ca> wrote:

    On Wed, 27 Nov 2024 12:53:01 -0800, john larkin <jl@glen--canyon.com> >>>>wrote:

    On Wed, 27 Nov 2024 08:53:41 -0500, legg <legg@nospam.magma.ca> wrote: >>>>>

    Anyone had experience using metalization on glass (mirror)
    as a ground plane or shield?

    Any data on conductivity etc?

    RL

    Why use glass? Why not copperclad FR4?

    Rugged repeated use - subjected to fire and impact.

    Will be possibly burning FR4 in contact with it.

    A work surface.

    RL

    Stainless steel is pretty conductive.

    which glass ain't . . .

    Mind you, they're both just peachy to bend, drill, or to
    work with simple hand tools - luckily avoided here once
    sharp edges are tamed.

    The consideration only came up when the basic material
    showed up, free, begging for safe 'disposal'.

    Mirrors? We went on a garden tour and one guy had a tiny yard with
    mirrors on the fences. It looked huge, great fun. He served tea and
    cookies to the visitors.

    I'm not interested in plants like Mo is, but the garden tours are fun.
    One guy near the Presidio has a waterfall in his back yard, Lobos
    Creek.

    A micro-hydro project?


    Not sure if the idea might be useful to others, elsewhere.

    RL

    I recall some sort of conductive glass, antistat level, but you
    probably don't have that.

    There are antistat sprays, which I think are mildly hygroscopic, for
    floors and such.

    Well, I mentioned earlier that dish soap can get films in the
    megohm/square region.

    Encourages hygene, too.

    RL

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  • From john larkin@21:1/5 to legg on Sat Nov 30 08:22:04 2024
    On Sat, 30 Nov 2024 10:05:47 -0500, legg <legg@nospam.magma.ca> wrote:

    On Fri, 29 Nov 2024 07:59:08 -0800, john larkin <JL@gct.com> wrote:

    On Fri, 29 Nov 2024 08:46:25 -0500, legg <legg@nospam.magma.ca> wrote:

    On Thu, 28 Nov 2024 07:16:55 -0800, john larkin <JL@gct.com> wrote:

    On Wed, 27 Nov 2024 22:08:13 -0500, legg <legg@nospam.magma.ca> wrote:

    On Wed, 27 Nov 2024 12:53:01 -0800, john larkin <jl@glen--canyon.com> >>>>>wrote:

    On Wed, 27 Nov 2024 08:53:41 -0500, legg <legg@nospam.magma.ca> wrote: >>>>>>

    Anyone had experience using metalization on glass (mirror)
    as a ground plane or shield?

    Any data on conductivity etc?

    RL

    Why use glass? Why not copperclad FR4?

    Rugged repeated use - subjected to fire and impact.

    Will be possibly burning FR4 in contact with it.

    A work surface.

    RL

    Stainless steel is pretty conductive.

    which glass ain't . . .

    Mind you, they're both just peachy to bend, drill, or to
    work with simple hand tools - luckily avoided here once
    sharp edges are tamed.

    The consideration only came up when the basic material
    showed up, free, begging for safe 'disposal'.

    Mirrors? We went on a garden tour and one guy had a tiny yard with
    mirrors on the fences. It looked huge, great fun. He served tea and
    cookies to the visitors.

    I'm not interested in plants like Mo is, but the garden tours are fun.
    One guy near the Presidio has a waterfall in his back yard, Lobos
    Creek.

    A micro-hydro project?

    No, but very decorative.

    There are only two creeks left in San Francisco... all the rest are
    now in pipes underground. Lobos Creek flows into the ocean and Islais
    creek intoo= the bay. Islais is two blocks from our house and from my
    office, in Glen Canyon, and is flowing now that the rains have
    returned.

    We have hiking engineering brainstorm sessions in Glen Canyon, which I
    think work better that sitting around in a conference room.



    Not sure if the idea might be useful to others, elsewhere.

    RL

    I recall some sort of conductive glass, antistat level, but you
    probably don't have that.

    There are antistat sprays, which I think are mildly hygroscopic, for
    floors and such.

    Well, I mentioned earlier that dish soap can get films in the
    megohm/square region.

    Encourages hygene, too.

    And leakage currents?


    RL

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