120' monopole
*EMP & Communications Systems*
Electro Magnetic Pulse is a deathly real threat to the United States of America. Read War's EMP facts and GVI's EMP articles for a bit more understanding. This article focuses on the EMP effects on communications systems.
Real life isn't like Basher's "Pinch" in Ocean's Eleven that knocked out the power in Las Vegas for 30 seconds. Yea, the power will go out, but it ain't coming back on.
The other day the question was asked about putting a cell phone in a Faraday box and the poster wondered if it would possibly work after an EMP blast. Well, it's a yes/no answer. The phone itself will probably survive and work fine if you want to play a game with it. However, it will probably not be able to make a phone call, well why? If the phone survives it should work right? Nope, not hardly.
An EMP blast will cause approximately 50 kilovolts (50,000 volts) of electricity to build up on each meter of wire (any metal) that it touches. There isn't a lot of area inside of an electronic device for electrons to build up on, as War stated in his article. So that's why a cell phone, even one that's not protected in a Faraday box will most likely survive. The problem is the infrastructure that the phone relies on in order to operate. Take a look at this article http://www.alpharubicon.com/elect/cellphonesite.htm and look at all the metal. Electrons will be all over every piece of metal you see. The natural route for any type of electricity is to go to GROUND.
Most communications systems including cellular, 2-way business, public services, FM broadcast and television rely on having their systems located in high areas and usually on huge towers. After an EMP event, you can write off most all these plus the electrical grid. The EMP blast will do the same thing to communications systems as it will to the power grid and here's why.
Let's go back to the 50 kV/m (kilovolts per meter) of wire. Now let's look at a cellular phone site, many of which are hundreds of feet tall and are completely metal. How much power can build up. Let's look at this site here, it's a 120' monopole and the transmission lines run inside of it. That'll help shield from EMP because of skin effect. There will still be voltage on those lines because it will enter from the top where the antennas are and where the transmission line is exposed.
120' monopole
There are 3.28 feet in 1 meter. For easy figuring we'll round to 3.3 feet. A 120' monopole equals 36.4 meters of length, not including the diameter of it. That adds on a LOT more surface area for the electrons to build up on. In other words this monopole will build up more voltage than 120' of 1/2" diameter of wire. Remember the keyword in War's article "surface area". The more surface area the more build up!
So let's assume the best case scenario with the monopole and say it's 36.4 meters and will build up 50 kV/m. 50,000 multiplied by 36.4= 1,820,000! So there will be 1 million, 820 thousand volts built up and wanting to go to ground. That's a minimum. Yes, monopoles and towers are grounded, BUT the grounding systems are intended for lightening and noise. A lightening strike hitting a tower or monopole can be between 10 and 120 million volts according to War's info on lightening.
Here's a quote from it: "While EMP may build up 50,000 volts per meter of wire, lightning delivers 10 to 120 million volts in an area of about a foot diameter. EMP delivers it's voltage in NanoSeconds, while a lightning strike may deliver it's voltage over a second or maybe even 2.
*Lightning delivers more voltage to a smaller area over a longer amount of time.
*EMP delivers a slightly smaller voltage to a HUGE area over an instant of time "
Because a lightening strike is much longer the power can dissipate to ground and the ground wires can handle it. However, since EMP moves so much faster that built up voltage will not be able to go to ground. Yea, some will make it, but all of that power going through the copper wires will most likely vaporize them (as stated in War's article about wires vaporizing). Some voltage will get in to the 'brains' of the operation and fry them.
Look at all the metal for electron buildup
Some cellular sites (also FM broadcast and most other types of sites) have the transmission line outside of the structure, which means it would be exposed to an EMP blast. So let's see what kind of damage can be done.
Let's think of a 300' tall tower. US Cellular and AT&T have sites on it. A cell site is set up in to 3 sectors and generally each sector contains 2 antennas. So AT&T has 6 antennas and so does US Cellular. Each antenna has it's own transmission line running to the building on the ground where the radio equipment is. That's 12 transmission lines total. The shields of the transmission lines are ELECTRICALLY connected to the tower for grounding. Each line is typically grounded 3 times! Let's start adding up some surface area.
A 300' tall tower is 90.9 meters tall. Let's not forget to add in all of the cross bracing, it's metal too so it'll also build up electrons. Let's be conservative and say there is only 250' of cross bracing (there'd be a lot more in reality). 250' equals 75 meters!
91 meters + 75 meters= 166 meters (again, that's a very generous figure, cross bracing adds up in length FAST.)
Now 300' of transmission line per antenna will be adding up electrons also. 91 meters multiplied by 50 kV = 4,550,000 That's per line. Take that # times 6 lines and that's 27,300,000 volts for one carrier. Remember this site has 2 carriers so we need to double that number. There will be 54.6 million volts of bad juice rolling down 12 lines !!
54.6 MILLION VOLTS of power could realistically be heading to the bottom of the transmission lines faster than you can blink. Let's not forget the tower too. 166 meters times 50 kV = 8,300,000 volts!
Ok, that's big numbers. 54.6 million + 8.3 million is 62.9 MILLION FRIGGIN' VOLTS which have the potential to land at bottom of that tower in a few nanoseconds! There is no way all of that voltage is going to bleed off to ground before frying the equipment. All of that power won't dissipate through the grounding system. It'll be like in War's article, things will fry, explode and vaporize. The entire site will be destroyed. Remember, I said my figures were very conservative, there is actually a lot more surface area on a tower for electrons to build up! Also remember, the more stuff on a tower the more surface area there is for build up. Much electronic equipment is static sensitive and can be damaged with a static spark from your finger tip. A bit of static is only a few thousand volts. Just imagine millions of volts getting to it.
So like I said, even if your phone survives it probably ain't gonna work, now you know why.
Some people will put AM & FM radios in a Faraday box which is fine. However, like a cell phone they might survive, but if the radio station's broadcast equipment doesn't it'll do you no good. Let's look at a FM site. http://www.alpharubicon.com/elect/changebroadbandantennajaden.htm
The tower is 190' tall. From the top antenna there is probably about 220' of length. Look at the pictures of the antennas, there's a few feet of length inside of them. It all adds up. Just imagine the power building up on all of it. The tower will build up over 2,850,000. The antenna and transmission line will build up over 3,330,000. Sometimes the transmission line for an FM station is also grounded to the tower, so it has a great electrical connection. What happens when 6.18 million volts hits the transmitter? Well, "magic smoke" is a light statement.
AM broadcast stations are just as vulnerable. Because of such low frequencies (520 kilohertz up to 1600 kilohertz) they require a HUGE antenna to broadcast. Often times AM broadcasters insulate the tower from the ground and use it for the antenna. (Remember, electricity likes to go to ground and now the structure is insulated!) Let's take an AM station that broadcasts on 1030 KHz (aka 1.030 MHz). Their antenna tower would be about 525' high or roughly 160 meters. A self supporting tower has a lot more metal on it than a guyed tower. AM'ers use both. Anyway a 160 meter high tower would be up at least 8,000,000 volts. Because of so much power, it stands to reason some of it will go to ground through the bolts that are in the concrete base. The same goes for all towers. I wouldn't be surprised if that amount of voltage sparking from the bolts to the ground through the concrete actually fractured the concrete.
So yes, it it highly doubtful that much for communications equipment will survive.
If there's an EMP blast in the US, it's probably not going to affect the other side of the world much other than making a mess out of the atmosphere. Radios work by using electromagnetic waves (radio waves). Here in the US after a blast all of those electrons rolling across the country really really screw up wireless communications. Yea, even ham operators will have a hard time on the HF bands. I've seen documentation that predicts the atmosphere will be severely screwed up for many days afterward. It is predicted to take years to get back to normal. That also means that if your shortwave radio survives a blast and so do the broadcasters on the other side of the world, there will be a lot of atmospheric noise here and you most likely won't be able to receive anything.
Now, since I don't happen to have a nice nuke bomb here to test with, the info I gave is from the facts we know and what 'makes sense'. With NK being as stupid as they are, we might find out sooner than later.
Jaden
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