Tag Archives: Disaster Communications

EMP Radio Preparedness Primer 1: Understanding the Electromagnetic Pulse

Will modern portable radios survive an EMP? Likely not without protection.

Here on the SWLing Post we tend to cover topics related to shortwave radio, ham radio and international broadcasting. We also cover an array of other topics our contributors and readers find appealing.

Lately, I’ve noticed an uptick in one particular question–at least, variations of it–from readers and people who found our site searching for emergency/preparedness radios:

What radio can survive an EMP?”

or

“How could I protect a radio from an EMP?”

What is an EMP?

In case the term EMP is new to you, check out this explanation from Wikipedia:

An electromagnetic pulse (EMP), also sometimes called a transient electromagnetic disturbance, is a short burst of electromagnetic energy. Such a pulse’s origination may be a natural occurrence or man-made and can occur as a radiated, electric, or magnetic field or a conducted electric current, depending on the source.

EMP interference is generally disruptive or damaging to electronic equipment, and at higher energy levels a powerful EMP event such as a lightning strike can damage physical objects such as buildings and aircraft structures. The management of EMP effects is an important branch of electromagnetic compatibility (EMC) engineering.

Weapons have been developed to create the damaging effects of high-energy EMP. Misleading or incorrect information about such weapons, both real and fictional, have become known to the public by means of popular culture and some politicians’ claims. Misleading information includes both exaggeration of EMP effects and downplaying the significance of the EMP threat.

In short? A strategic EMP could cripple our electrical grid and potentially many other electronic and digital devices.

Most of us are concerned with wide-spread disruptions from electromagnetic pulses originating from:

  • Man-made atomic weapons
  • Natural occurrences, like solar flares/storms

A solar flare erupts on the far right side of the sun, in this image captured by NASA’s Solar Dynamics Observatory. (Image: NASA/SDO/Goddard Space)

No doubt, with North Korea testing nuclear weapons and their delivery systems, the latest surge in questions are a reaction to this behavior. Moreover, North Korea’s state news agency has been explicit about their intention to deploy and detonate an EMP weapon over the United States.

I’ve never been as concerned about man-made EMPs…well, until recently. Rather, I’ve been more concerned about the EMP potential of our local star––the Sun.

Whennot if, we receive a strong EMP from a solar storm like that generated in 1859, known as the Carrington Event–our electronic infrastructure could very well be severely crippled, perhaps even for the better part of a decade.

Concerning, isn’t it?

Let’s come back down to Earth…

As the Wikipedia article indicates, there’s a lot of confusing and misleading information out there regarding EMPs.  And while some of this reportage underplays the seriousness of this very real, if rare, concern, a great deal of it, including the fiction about it, is more alarming than it needs to be.

So I turned to a good friend who happens to be an expert on EMPs.

My pal has worked for thirty-five years designing military radar equipment, broadcast transmitters, and automotive electronics.

His profession requires that he knows how to “harden” equipment against all types of EMP threats, and thus is regarded as a specialist in this field. Because of his professional ties he’s asked that I withhold his name.

My EMP expert friend is also very pragmatic. That’s why I asked him to explain how EMPs might affect us both generally and specifically, in terms of communications and the radio world.

I asked him to address what effects an EMP might have, both nuclear and solar originated, and how what practical preventative measures we might take to mitigate the damage to our radio equipment. His reply follows…


Anxiety over EMP seems to recur every time there is a change in the established order. The premise of Mutually Assured Destruction that has kept us ‘safe’ in the nuclear age vanishes when confronted by a suicidal adversary. That _seems_ to be the case at present.

So let’s look at the facts available:

A nuclear EMP has its peak energy in the 1 MHz range, with appreciable energy even in the 1 GHz range. It has field strengths of up to 50 kV/m.

The wiring inside of modern consumer electronics, including PCB traces, is close to GHz wavelengths, so they will be effective [in] receiving that energy and carrying it to any electronics [to which] it is connected.

There was a series of articles in QST 30 years ago by Dennis Bodson (W4PWF) that should be the go-to reference:

[Note: the following links require that you’re logged into the ARRL website and are a current member.]

The author related results of a number of tests on equipment by the US in EMP simulators.

The impact on vehicles

One observation was that vehicles were not affected.

As a former automotive engineer, I can attest to the lengths to which designers go to make automotive electronics resistant to damage. A vehicle must be designed to withstand operation with no battery, reverse battery voltage, inductive surges, and other abuse. Automotive electronics are designed to operate under radio and TV transmitters without damage.

There are of course anecdotal accounts of ham equipment causing vehicle computers to go haywire, but if (and that is a BIG IF) the equipment was designed properly, there will not be damage. One area where EMP will cause damage in a vehicle is the car radio. It is tied to an antenna that will conduct the surge directly into the very fragile receiver circuitry.

That said, the amount of electronics in a vehicle is hugely increased since these articles were written in 1986, and even after I left the automotive industry in 2006.

The specs for automotive EMI resistance have not changed in that time, though.

EMP hardening

The way that you keep EMP out of any object is to surround it in conductive metal, so that no gaps exist. Think of a microwave oven that must keep the radiation _in_. The screen in the door window has tiny holes you can see through, but much smaller than the wavelength of the oven. Where microwave leaks are most likely to occur is around the door, where the metal shield is not continuous.

If you want to shield electronics from EMP, the coverage by the metal shield must be continuous. A gap or slit will permit the energy to penetrate.

Sample of reclosable ESD bags.

In the silvered plastic Electrostatic discharge (ESD) bags that are very popular for EMP protection, the zip-lock seam is the weak point in the shielding. You can very easily just use two bags, one inside the other, with the seams in opposite directions, to make a greatly improved shield.

Aluminum foil is a great shielding medium, [and] it’s cheap and plentiful.

Use a big piece, and wrap several overlapping layers. It’s hard to do better.

Many of the solutions used for EMI and RFI lose their effectiveness in the high field strengths of an EMP.

The ferrite snap-on chokes saturate at high magnetic field intensities, and lose their permeability, and the ability to stand off conducted surges.

Use of ammo boxes or file cabinets for EMP protection [a popular method promoted by many on the Internet] is of limited effectiveness because of the large gaps between sheets of metal, and the poor conductivity of steel.

A galvanized trash can is a better solution, because of the conductivity of the zinc galvanization.

The gap around the lid should be covered with adhesive copper tape, available at craft and garden supply stores.

Batteries

Batteries are not affected by EMP. But a battery pack with a built in smart charger may be.

Be aware that LiFePo batteries tend to have built-in smart charge controllers.

Store battery packs safely shielded also––but make sure the terminals cannot contact the metallic shield and cause a short!

Tube/Valve radio equipment

Vintage tube radios will likely survive an EMP, but how do you power them without mains electricity? By modern standards, valve gear is power hungry!

Vacuum tube equipment is very resistant to EMP, as [it] can withstand arcing and surges with no damage.

The bigger question is, how do you power it afterward?

Suppress Surges and Unplug

Much of the damage from an EMP will be conducted, coming in on power lines. Always unplug any critical electronics when not in use. Also, put a surge suppressor on every outlet [into which] you have electronics plugged.

It is cheap insurance. Even of you are not in line-of-sight of an EMP, the conducted surge can wipe out costly appliances. I do this as protection anyway because of my ham antenna. When lightning hit the tree outside my house ten years ago, we only lost two CFL bulbs, while every neighbor on our block lost TVs, microwaves, and washing machines.

Gamma Ray Bursts

EMP radiation should be distinguished from ionizing nuclear radiation. Exposure to a gamma ray burst from near proximity to a nuclear event will disrupt electronics also, but that is an entirely separate topic.

Most Important Communication Medium During Disasters

Photo by Tania Malréchauffé on Unsplash

(Hopping on soap box) The most important form of communication is that which covers the shortest distance. Get to know your neighbors. When bad things happen, they will be the people who will help you out, and be the most grateful when you help them. We’re seeing this happen on a massive scale in Houston [Florida and Puerto Rico] right now. (off soap box).

My Disclaimer

The subject of EMP is very controversial. There is a tremendous amount of misinformation out there. There is disagreement even among the experts.

The problem is that since aboveground nuclear testing…ended a generation ago, there is very little relevant information existing, since semiconductor electronics were in their infancy at that time this occurred. Most information that there is has come from EMP simulators, which are assumed to create waveforms close to that of a nuke. We all know…how risky assumptions can be!

But we do know how to make shielding, and we do know what kind of effects will damage electronics, and we can use this knowledge to try to assure that the preparations we make will be sufficient to protect our electronics.

All of these are very hostile EMI/EMC environments, and the specifications for their design are very strict. These designs offer guidance as to how to create EMP resistant electronics. What are offered are opinions, but hopefully well informed opinions. If I’m wrong, I won’t argue about it, there is more at stake than ego.


Answering common questions

Many thanks for these useful insights and explanations. And now, with all of this in mind, let’s re-evaluate questions about EMPs and radios:

“I understand tube/valve radios can survive an EMP. Which model should I buy?”

My answer: You’re correct; as discussed above, vacuum tube equipment is very resistant to EMP, as it can withstand arcing and surges with no damage.

However…without mains power (the most likely result from a strategic EMP) how will you power tube gear––? Many tube radios were never designed to be operated from a battery source. Those that could, require batteries with a fairly exceptional amount of capacity. Vacuum tube radios are not efficient compared with modern solid-state battery-powered radios.

If you have an generator or power source that is hardened to survive an EMP, and you have a plentiful supply of fuel to run it, then you may consider a tube radio. Otherwise––or better yet, additionally––protect a much more efficient portable radio.

“What radio can survive an EMP?”

Any radio that is properly shielded from the effects of EMP should survive an EMP.

“How can I protect a radio or other portable electronics from an EMP?”

After you’ve chosen which radio to protect, take the extra precaution of removing any attached telescopic antenna. Most antennas are held in place with a simple tiny stainless steel screw/bolt. Unscrew it, pull the antenna off, place both pieces in a small bag and keep it with the radio.

Next, place the radio in a container that will act as a “Faraday cage” to exclude an EMP’s electrostatic and electromagnetic influences. There are a number of commercial products specifically designed for this use, but it’s more simple and affordable to adopt one of the procedures our expert outlines above.  Let’s re-cap:

ESD Bags

Find a bag that’s large enough to fit your radio; many of the bags designed for SATA hard drives should fit more compact radio models.

Place the radio (and its detached antenna) into the ESD bag and close the zip seam.

Then, place the ESD bag containing your radio equipment into another ESD bag, making sure the bag seams are on opposite ends.

Aluminum Foil

 

Consider wrapping your radio or electronic device in its box. Not only does it insulate the contents, but it makes an easier surface to wrap in foil.

Wrap the radio in at least three layers of aluminum foil. Make sure all seams are tightly sealed with each layer of foil. Each layer should completely enclose and protect the radio.

I wrapped this radio in three layers of foil, carefully sealing seams on each layer.

Galvanized Trash Can

As mentioned above, items can be placed in a galvanized trash can for protections.

Simply line the inside of the can with a dielectric material (cardboard, thick cloth, foam, or something similar) so the contents cannot touch the sides, bottom, or lid of the can.

It may be overkill, but I might also wrap my electronics in aluminum foil before placing it inside, again making absolutely certain your equipment in its foil wrap is NOT touching the metal of the can.  This would simply serve as a secondary–redundant–layer of protection.

If you live in a humid area, you might put some sort of moisture protection inside as well.

On to Part 2…

In the final part of our primer, we’ll take a look at what sort of radios you should consider packing away for emergency use, discussing selection criteria.

I’ll link to this article in the coming weeks, too, once it’s published, so stay tuned for more on this intriguing subject. Follow the tag: EMP

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Poynter: “Hurricane Harvey couldn’t silence Texas radio stations”

(Source: Poynter via Kim Elliott)

When Hurricane Harvey’s intensity became clear, employees at 93Q in Houston reserved hotel rooms across the street from the station. They were going to be very busy.

The on-air talent slept in the Cox-owned radio station for days, said Bill Tatar, digital content manager at Cox Media Group Houston. When they weren’t on-air, they did Facebook Live hits.

93Q is not normally an all-news station. But when emergencies hit, local radio stations can convey vital information: which streets are open, what shelters are taking people in and where communities can rally once the water begins to recede.

“Radio has been all over Harvey doing what radio does; immediately helping with updated information,” said Valerie Geller, a radio consultant. “Most stations dropped the format and went ‘all Harvey,’ taking calls, and across the country, stations are sending help and raising money.”[…]

Continue reading online at Poynter.

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Brian FM: a post-disaster FM radio station in New Zealand

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(Source: Radio New Zealand via London Shortwave)

Radio ‘nutters’ move in to help shaken Kaikoura

A fortnight after the Kaikoura earthquake, most of the businesses along West End, the town’s main street, are still closed – the interiors darkened, some shopfronts cordoned off.

But the door of one of those shopfronts is open, and from it, the strains of Brian FM come floating out.

Who’s Brian?

“I have no idea,” Chris Diack says.

“People are wanting to walk in and talk to Brian all the time and there’s no Brian – there’s Chris and Robert.”

Mr Diack and his offsider, Robert Jeffares, have been broadcasting from their makeshift studio for a week now, after convincing the owner of a local frequency that was not being used to let them take over.

The content is mostly “parish pump information”, says Mr Diack – the level of detail the rest of the country might not need to hear but which is invaluable to locals trying to find out where their next hot shower might be coming from.

“The water’s off, you can’t use the toilets, if you need to use the toilets use the portaloos, and where are they … Four Square’s open at midday, get along there and get some milk, bread and butter… You couldn’t buy butter for love nor money in Kaikoura.”

In between broadcasting the minutiae of post-quake life, they conduct interviews with the district mayor, civil defence, the Salvation Army, and errant RNZ reporters who wander in to the studio.[…]

Continue reading on Radio New Zealand’s website.

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“When everything else fails, amateur radio will still be there—and thriving”

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(Source: ARS Technica)

by Rupert Goodwins

It’s a good time to be technical. Maker communities are thriving around the world, tools and materials to create and adapt are cheaper and more powerful now than ever, and open source hardware, software, and information mean that if you can think it, you can learn how to do it and then make it happen.

For one group of technological explorers, this is more than just a golden age of opportunity: it’s providing the means to save one of the oldest traditions in electronic invention and self-education, one that helped shape the modern world: amateur radio. That matters.

Radio amateurs get a sweet deal, with effectively free access to many gigahertz of the same radio spectrum that companies pay billions for. They’ve earned it. Throughout the history of electronics, they’ve been at the borders of the possible, trying out ideas that commerce or government deem impossible or pointless—and making them work. One example of hundreds: Allied military comms in World War II needed a way to reliably control the radios used by front-line forces, replacing tuning knobs with channel switches. Hams had the answer ready and waiting: quartz crystal oscillators. (That’s part of computing history too—you’re probably using about ten of them right now.).

[…]Then, there’s backup. Take the European HAMNET, for example. That’s a four-thousand-node high speed data network covering a large part of continental Europe and providing full IP connectivity at megabit speeds. It connects to the Internet—ham radio owns 16 million IPV4 addresses, believe it or not—but is independent of it, doing its own robust and flexible routing. If the Internet was to go away, HAMNET would still be running. The same’s true of nearly all ham radio infrastructure: when everything else fails—power, comms, roads—ham radio is still there, and these days it can be a full-fat digital medium.[…]

Continue reading at ARS Technica…

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Reminder: Emergency radio and a chance to win a prepper radio package

Click to enlarge

Enter our challenge and you could win this prize package worth over $200 courtesy of CountyComm!

Let’s imagine that your area suddenly loses power–as well as cell phone and internet service–for an indeterminate period. Home and personal electronics remain unaffected, but must be powered off-grid (without mains power).  Moreover, you may be required to evacuate your home…perhaps even on foot.

In preparation for this event, what portable radio kit would you assemble?  

Submit your answer to this question and you could win a preparedness prize package courtesy of CountyComm!

All entries must be received by November 21, 2015.

Click here to read about this challenge and how to submit your answer!

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Virtual Radio Challenge IV: Emergency radio and a chance to win a prepper radio package

GP5SSB-Front

The CountyComm GP5/SSB portable SW/AM/FM radio is just one of many items in this prize package!

UPDATE: This challenge is now closed.  Click here to read about the winning entries.

The SWLing Post attracts readers and enthusiasts from all walks of life. In the past, we’ve put together Reader Challenges based on actual questions we receive from readers, usually looking for the best radio kit for a unique situation or location. Our first challenge sought gear for the most remotely inhabited island on the planet; the second, for a village in the Himalayas; and the third, for an Appalachian Trail thru-hiker.

This time we’re taking a slightly different angle, but nonetheless representative of a quite significant (and growing!) number of reader queries: What is the best radio for use in an emergency? Or, as we’re often asked,”What is the best prepper radio?”

There are many ways to answer this question based upon the scenario a reader is confronting. To help define a scenario for this challenge–perhaps the first in a few similar radio challenges–I enlisted the help of my good friend, David Cripe (NM0S). Dave, an engineer and radio/kit designer, is something of a modern day MacGyver and preparedness expert. Not to mention, a very cool guy.

Dave agreed not only to help author an emergency scenario (below), but has also agreed to judge the reader challenge responses.  Dave will select his favorite from among the best  entries.

But there’s more: CountyComm Government Products Group has generously offered a comprehensive prize package for the winning entry!

Interested? Keep reading…

The scenario

ivan-hurricaneAs is often said, stuff happens. Indeed, our modern communication infrastructure is a fragile thing. Let’s imagine that your area suddenly loses power–as well as cell phone and internet service–for an indeterminate period. Home and personal electronics remain unaffected, but must be powered off-grid (without mains power).  Moreover, you may be required to evacuate your home…perhaps even on foot.

Electricity-Pylon-TowerDoes the above scenario seem far-fetched?  Actually, this is just the sort of scenario we often see occur in regions throughout the world as the result of natural disasters (and occasionally human sabotage), and it’s the scenario we’ll mentally prepare for in this exercise.

In preparation for this event, what portable radio kit would you assemble?  In particular, you’ll want to look for an optimal combination of features and portability for price, ($400 US for all your kit). And it isn’t just the radio we’re interested in, but also how you intend to use it.

Therefore, how do you intend to:

  1. obtain information about local and world events?
  2. communicate within your local region to assist emergency services?
  3. pass messages to friends and family over long distances?
  4. power your kit for an indeterminate amount of time?

Limitations

Rather than making this virtual challenge restrictive, the following limitations are designed to make the challenge more fun and create a level playing field for all participants.

  1. Once again, you’re limited to a (virtual) budget of $400 US to procure your supplies; ideally, this will include the shipping costs of all purchase(s) you make.
  2. You may select new, used, or homebrew gear, but you must base your choices on reality (i.e., actually find item(s) online and document the price and time of availability). If you “shop” eBay, for example, make sure you’re using the final purchase price, not the current or opening bid. If you do locate something used on eBayQTH.comQRZ.com, or at Universal Radio, for example, do include the link to the item (just to add to the fun). If you enter a homebrew radio, it should be based on something you’ve either built or used, and must include a photo. Of course, you can use multiple radios, but keep in mind the amount of space and weight these will consume in your evacuation or “bug-out” bag.

The prize package

Click to enlarge

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CountyComm is generously offering the selected entrant of this contest a prize package that includes the following items, useful whether there’s an emergency or not:

The total value of this kit is $209.94 US!

How to enter the challenge

This challenge will continue for one month, ending on November 21.

To enter, simply describe the kit you’ve chosen and how you would address the scenario above. Please be specific, but also as concise as you can. If you’re describing a radio or gear you already own, consider sending photos, as well.

Simply send your entry to SWLingPostContest@gmail.com.

Spread the word!

If you’re active in a preparedness group locally or online, please help us spread the word in your group!  Although there is a serious element to this exercise, in that it might really help you or another reader in an emergency situation, it’s intended to be fun; enjoy the challenge, and good luck!

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“Why The Humanitarian Community Should Shape The Future Of Shortwave”

300px-Hurricane_Isabel_from_ISSAs World Radio Day approaches, writer Mehmet Burk (founder of ReliefAnalysis.com) considers the importance of shortwave radio, especially in terms of disaster relief.

Burke posted the article, Why The Humanitarian Community Should Shape The Future Of Shortwave on Interaction.org. Here’s a quote:

“In the 1980s and 1990s, shortwave radio was an audio version of today’s internet. Almost every nation on earth broadcast a shortwave signal and vital humanitarian news and local depictions of current events could literally be heard half a world away. The Internet did to shortwave broadcasting market much like what it did to print newspapers.[…]

But radio remains the most wide-reaching media platform in the world today. In areas like Africa and the Pacific, it is the dominant form of communication. Like no other form of media, radio can bridge the digital divide and literacy divide in regions across the globe. Radio receivers can be made to be inexpensive, ruggedized, and indispensable in a disaster or humanitarian situation. In the future, shortwave receivers may even simply be stand-alone microchips we can activate using our smartphones and tablets.”

I’m honored that Burk reached out and even quoted me in this article.

Click here to read: Why The Humanitarian Community Should Shape The Future Of Shortwave.

Many thanks to Mehmet Burk for considering radio’s importance in the wake of disaster and honoring World Radio Day 2014!

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