[HCARC] EMP bursts--Re: HCARC Digest, Vol 18, Issue 2
Michael R Perez
mikerey.perez at me.com
Tue Oct 2 18:56:56 EDT 2012
I AM in awe, Kerry.
Great knowledge.
Thanks,
Michael Pérez
Sent from my iPhone
On Oct 2, 2012, at 11:03 AM, hcarc-request at mailman.qth.net wrote:
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> Today's Topics:
>
> 1. Faraday Cage (Gary and Arlene Johnson)
> 2. Fresh Eggs - Last Call (Gary and Arlene Johnson)
> 3. Re: Faraday Cage (Kerry Sandstrom)
> 4. Re: Faraday Cage (Gary and Arlene Johnson)
> 5. Re: Faraday Cage (curtiswe at ktc.com)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Mon, 1 Oct 2012 18:16:30 -0500
> From: "Gary and Arlene Johnson" <qltfnish at omniglobal.net>
> Subject: [HCARC] Faraday Cage
> To: <hcarc at mailman.qth.net>
> Message-ID: <F85046E9B0754552BF3BECD0EE87651F at Minnie>
> Content-Type: text/plain; charset="iso-8859-1"
>
> I guess it's time to liven up the Reflector again with a question about Faraday Cages.
>
> I am in the process of building out my Radio Room as part of my shop. Since I am building walls largely from scratch, I wonder what the effect would be of lining each of the walls and the ceiling with 1/4 inch aluminum mesh would be and what it's effect would be towards making this 10x12 room into a Faraday Cage to seal out electromagnetic waves from something like a Pulse Weapon or geomagnetic storm. I would be able to overlap all the openings with either the mesh or with solid steel and all parts of the cage would be connected to ground.
>
> Would it work???
>
> Gary J
> N5BAA
>
>
>
> ------------------------------
>
> Message: 2
> Date: Mon, 1 Oct 2012 18:19:32 -0500
> From: "Gary and Arlene Johnson" <qltfnish at omniglobal.net>
> Subject: [HCARC] Fresh Eggs - Last Call
> To: <hcarc at mailman.qth.net>
> Message-ID: <CE2D10E15C4E4D7C942459311185344F at Minnie>
> Content-Type: text/plain; charset="iso-8859-1"
>
> I will have plenty of fresh eggs if anyone is interested in my bringing them to the meeting on Thursday. $3.25 a dozen without an empty carton, $3.00 if you bring me an empty carton.
>
> Gary J
> N5BAA
>
> ------------------------------
>
> Message: 3
> Date: Mon, 1 Oct 2012 19:51:26 -0500
> From: "Kerry Sandstrom" <kerryk5ks at hughes.net>
> Subject: Re: [HCARC] Faraday Cage
> To: "Gary and Arlene Johnson" <qltfnish at omniglobal.net>
> Cc: HCARC Reflector <HCARC at mailman.qth.net>
> Message-ID: <30EA6FC561434856AD33B081DA9B072A at NumberCruncher>
> Content-Type: text/plain; format=flowed; charset="iso-8859-1";
> reply-type=original
>
> Gary,
>
> I've spent many years working in and on shielded enclosures. There are
> several reasons why it wouldn't work. First of all, EMP and geomagnetic
> storms are low frequency events. The geomagnetic storms have large
> frequency components of perhaps a few Hertz. EMP from a high altitude
> nuclear detonation has frequency components almost entirely below 1 MHz and
> largely below 100 kHz. The only way to shield from these low frequencies is
> with a large amount of ferrous metal, steel! Copper won't do nor will
> aluminum. Commercial (and expensive) shielded enclosures are only rated
> down to 100 kHz, and even at 100 kHz the attenuation is several 10's of dB
> below what it is at 1 MHz. Modern shielded enclosures are often constructed
> of particle board sandwiched between sheets of copper plated steel. Even
> with the steel, they provide almost no attenuation of magnetic fields.
> Shielded enclosures also have power line filters, waveguide below cutoff
> filters for air vents, and very strict methods for bringing coaxial and
> fiber optic cables in. Telephone lines are seldom brought in but if they
> are they also require filters. The filters are typically rated for 100 dB
> attenuation above 14 kHz. Traditional copper wire screen rooms are even
> less effective at low frequencies. I suspect aluminum screen would be less
> effective than copper screen. The screens I've seen were about 1/8" or
> less.
>
> I am quite familiar with pulse weapons. Trust me, they are not a problem
> for us. Their range is extremely limited unlike a high altitude EMP which
> covers a radius of 1000's of miles. Unless you are an important target or
> the weapon is inaccurate by a 100 miles I don't think we have anything to
> worry about. Incidently, the field strength level normally used for EMP
> testing is 50 kV/m. For comparison, the electric field suceptibility level
> (MIL-STD-461) is about 200 V/m, some 48 dB less.
>
> The main threat from both EMP and magnetic storms is conducted energy on
> transmission lines, power lines and telephone lines that are perhaps 100's
> of feet to miles long. Unless you have excellent filters on all those lines
> and the filters are properly installed on a shielded enclosure, they will be
> ineffective. The most effective way to protect your ham station from EMP is
> to diconnect everything: power cords, microphones, keys, antennas, etc.
> Several years ago FEMA or CD or somebody like that did testing on ham gear
> and basically concluded that it is survivable if all wires are disconnected.
>
> By the way, a magnetic compass works just fine in a sheilded enclosure.
> Yes, a General did ask!
>
> This information is all available in the technical literature on EMI/EMC
> (electromagnetic interference/elctromagnetic compatibility). QST has had a
> few articles on EMP effects and protection during the cold war years. The
> last real US test of EMP was a device called "Starfish" about 61-62 time
> frame. It was launched from Johnston Atoll and was above the horizon in
> Hawaii. A 1976 Los Alamos Scientific Laboratory publication lists Starfish
> as 1.4 Megatons at an altitude of 400 km. This was the most powerful and
> except for a series of very small experiments called Argus, highest EMP
> test. The various test ban treaties have prevented any more test of high
> altitude EMP by all parties.
>
> That should keep you busy for a while!
>
> Kerry
>
>
>
>
> ------------------------------
>
> Message: 4
> Date: Mon, 1 Oct 2012 20:09:42 -0500
> From: "Gary and Arlene Johnson" <qltfnish at omniglobal.net>
> Subject: Re: [HCARC] Faraday Cage
> To: "Kerry Sandstrom" <kerryk5ks at hughes.net>
> Cc: hcarc at mailman.qth.net
> Message-ID: <8772511CFB2A4457B4EBE3F5C5DEF0C7 at Minnie>
> Content-Type: text/plain; format=flowed; charset="iso-8859-1";
> reply-type=response
>
> When I said Pulse weapon it was because that was all my poor meager mind
> could think of at the time. I meant EMP burst above the US. Just thinking
> since I was building the room anyway, I might just ask about it. I do find
> it interesting that the news talks about it every once in a while and no one
> seems to ever do anything about it. It's almost like someone is daring a
> country like Iran to try it. But why would we encourage it - maybe just so
> we knew who had tried it and could be reasonably sure of our retaliatory
> target.
>
> Gary J
> N5BAA
>
>
>
> Gary J
> N5BAA
>
>
> ----- Original Message -----
> From: "Kerry Sandstrom" <kerryk5ks at hughes.net>
> To: "Gary and Arlene Johnson" <qltfnish at omniglobal.net>
> Cc: "HCARC Reflector" <HCARC at mailman.qth.net>
> Sent: Monday, October 01, 2012 7:51 PM
> Subject: Re: [HCARC] Faraday Cage
>
>
>> Gary,
>>
>> I've spent many years working in and on shielded enclosures. There are
>> several reasons why it wouldn't work. First of all, EMP and geomagnetic
>> storms are low frequency events. The geomagnetic storms have large
>> frequency components of perhaps a few Hertz. EMP from a high altitude
>> nuclear detonation has frequency components almost entirely below 1 MHz
>> and largely below 100 kHz. The only way to shield from these low
>> frequencies is with a large amount of ferrous metal, steel! Copper won't
>> do nor will aluminum. Commercial (and expensive) shielded enclosures are
>> only rated down to 100 kHz, and even at 100 kHz the attenuation is several
>> 10's of dB below what it is at 1 MHz. Modern shielded enclosures are
>> often constructed of particle board sandwiched between sheets of copper
>> plated steel. Even with the steel, they provide almost no attenuation of
>> magnetic fields. Shielded enclosures also have power line filters,
>> waveguide below cutoff filters for air vents, and very strict methods for
>> bringing coaxial and fiber optic cables in. Telephone lines are seldom
>> brought in but if they are they also require filters. The filters are
>> typically rated for 100 dB attenuation above 14 kHz. Traditional copper
>> wire screen rooms are even less effective at low frequencies. I suspect
>> aluminum screen would be less effective than copper screen. The screens
>> I've seen were about 1/8" or less.
>>
>> I am quite familiar with pulse weapons. Trust me, they are not a problem
>> for us. Their range is extremely limited unlike a high altitude EMP which
>> covers a radius of 1000's of miles. Unless you are an important target or
>> the weapon is inaccurate by a 100 miles I don't think we have anything to
>> worry about. Incidently, the field strength level normally used for EMP
>> testing is 50 kV/m. For comparison, the electric field suceptibility
>> level (MIL-STD-461) is about 200 V/m, some 48 dB less.
>>
>> The main threat from both EMP and magnetic storms is conducted energy on
>> transmission lines, power lines and telephone lines that are perhaps 100's
>> of feet to miles long. Unless you have excellent filters on all those
>> lines and the filters are properly installed on a shielded enclosure, they
>> will be ineffective. The most effective way to protect your ham station
>> from EMP is to diconnect everything: power cords, microphones, keys,
>> antennas, etc. Several years ago FEMA or CD or somebody like that did
>> testing on ham gear and basically concluded that it is survivable if all
>> wires are disconnected.
>>
>> By the way, a magnetic compass works just fine in a sheilded enclosure.
>> Yes, a General did ask!
>>
>> This information is all available in the technical literature on EMI/EMC
>> (electromagnetic interference/elctromagnetic compatibility). QST has had
>> a few articles on EMP effects and protection during the cold war years.
>> The last real US test of EMP was a device called "Starfish" about 61-62
>> time frame. It was launched from Johnston Atoll and was above the horizon
>> in Hawaii. A 1976 Los Alamos Scientific Laboratory publication lists
>> Starfish as 1.4 Megatons at an altitude of 400 km. This was the most
>> powerful and except for a series of very small experiments called Argus,
>> highest EMP test. The various test ban treaties have prevented any more
>> test of high altitude EMP by all parties.
>>
>> That should keep you busy for a while!
>>
>> Kerry
>>
>>
>>
>> -----
>> No virus found in this message.
>> Checked by AVG - www.avg.com
>> Version: 2013.0.2677 / Virus Database: 2591/5790 - Release Date: 09/24/12
>> Internal Virus Database is out of date.
>>
>
>
>
> ------------------------------
>
> Message: 5
> Date: Tue, 2 Oct 2012 12:17:54 +0000
> From: curtiswe at ktc.com
> Subject: Re: [HCARC] Faraday Cage
> To: "Gary and Arlene Johnson" <qltfnish at omniglobal.net>,
> hcarc-bounces at mailman.qth.net, "Kerry Sandstrom"
> <kerryk5ks at hughes.net>
> Cc: Hcarc reflector <hcarc at mailman.qth.net>
> Message-ID:
> <419680420-1349180274-cardhu_decombobulator_blackberry.rim.net-102484500- at b2.c11.bise6.blackberry>
>
> Content-Type: text/plain; charset="Windows-1252"
>
> Is anyone else awed by the knowledge in this club? Good answer Kerry.
>
> I remember my Elmer, Herman, W5FES, SK, being excited about a steel shed shack as another layer of tvi/rfi protection. Like Kerry said, everything would have to be filtered.
> Sent from my BlackBerry? Smartphone by WCW
>
> -----Original Message-----
> From: "Gary and Arlene Johnson" <qltfnish at omniglobal.net>
> Sender: hcarc-bounces at mailman.qth.net
> Date: Mon, 1 Oct 2012 20:09:42
> To: Kerry Sandstrom<kerryk5ks at hughes.net>
> Cc: <hcarc at mailman.qth.net>
> Subject: Re: [HCARC] Faraday Cage
>
> When I said Pulse weapon it was because that was all my poor meager mind
> could think of at the time. I meant EMP burst above the US. Just thinking
> since I was building the room anyway, I might just ask about it. I do find
> it interesting that the news talks about it every once in a while and no one
> seems to ever do anything about it. It's almost like someone is daring a
> country like Iran to try it. But why would we encourage it - maybe just so
> we knew who had tried it and could be reasonably sure of our retaliatory
> target.
>
> Gary J
> N5BAA
>
>
>
> Gary J
> N5BAA
>
>
> ----- Original Message -----
> From: "Kerry Sandstrom" <kerryk5ks at hughes.net>
> To: "Gary and Arlene Johnson" <qltfnish at omniglobal.net>
> Cc: "HCARC Reflector" <HCARC at mailman.qth.net>
> Sent: Monday, October 01, 2012 7:51 PM
> Subject: Re: [HCARC] Faraday Cage
>
>
>> Gary,
>>
>> I've spent many years working in and on shielded enclosures. There are
>> several reasons why it wouldn't work. First of all, EMP and geomagnetic
>> storms are low frequency events. The geomagnetic storms have large
>> frequency components of perhaps a few Hertz. EMP from a high altitude
>> nuclear detonation has frequency components almost entirely below 1 MHz
>> and largely below 100 kHz. The only way to shield from these low
>> frequencies is with a large amount of ferrous metal, steel! Copper won't
>> do nor will aluminum. Commercial (and expensive) shielded enclosures are
>> only rated down to 100 kHz, and even at 100 kHz the attenuation is several
>> 10's of dB below what it is at 1 MHz. Modern shielded enclosures are
>> often constructed of particle board sandwiched between sheets of copper
>> plated steel. Even with the steel, they provide almost no attenuation of
>> magnetic fields. Shielded enclosures also have power line filters,
>> waveguide below cutoff filters for air vents, and very strict methods for
>> bringing coaxial and fiber optic cables in. Telephone lines are seldom
>> brought in but if they are they also require filters. The filters are
>> typically rated for 100 dB attenuation above 14 kHz. Traditional copper
>> wire screen rooms are even less effective at low frequencies. I suspect
>> aluminum screen would be less effective than copper screen. The screens
>> I've seen were about 1/8" or less.
>>
>> I am quite familiar with pulse weapons. Trust me, they are not a problem
>> for us. Their range is extremely limited unlike a high altitude EMP which
>> covers a radius of 1000's of miles. Unless you are an important target or
>> the weapon is inaccurate by a 100 miles I don't think we have anything to
>> worry about. Incidently, the field strength level normally used for EMP
>> testing is 50 kV/m. For comparison, the electric field suceptibility
>> level (MIL-STD-461) is about 200 V/m, some 48 dB less.
>>
>> The main threat from both EMP and magnetic storms is conducted energy on
>> transmission lines, power lines and telephone lines that are perhaps 100's
>> of feet to miles long. Unless you have excellent filters on all those
>> lines and the filters are properly installed on a shielded enclosure, they
>> will be ineffective. The most effective way to protect your ham station
>> from EMP is to diconnect everything: power cords, microphones, keys,
>> antennas, etc. Several years ago FEMA or CD or somebody like that did
>> testing on ham gear and basically concluded that it is survivable if all
>> wires are disconnected.
>>
>> By the way, a magnetic compass works just fine in a sheilded enclosure.
>> Yes, a General did ask!
>>
>> This information is all available in the technical literature on EMI/EMC
>> (electromagnetic interference/elctromagnetic compatibility). QST has had
>> a few articles on EMP effects and protection during the cold war years.
>> The last real US test of EMP was a device called "Starfish" about 61-62
>> time frame. It was launched from Johnston Atoll and was above the horizon
>> in Hawaii. A 1976 Los Alamos Scientific Laboratory publication lists
>> Starfish as 1.4 Megatons at an altitude of 400 km. This was the most
>> powerful and except for a series of very small experiments called Argus,
>> highest EMP test. The various test ban treaties have prevented any more
>> test of high altitude EMP by all parties.
>>
>> That should keep you busy for a while!
>>
>> Kerry
>>
>>
>>
>> -----
>> No virus found in this message.
>> Checked by AVG - www.avg.com
>> Version: 2013.0.2677 / Virus Database: 2591/5790 - Release Date: 09/24/12
>> Internal Virus Database is out of date.
>>
>
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> End of HCARC Digest, Vol 18, Issue 2
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