posted on Aug, 5 2012 @ 12:23 PM
Radio waves are a directional energy. They don’t have a tendency to bend corners very easily. The main way they can travel around corners at all is
by edge refraction. Unless you are close to the edge, or the wavelength is very long, then you will be in the shadow of the primary signal.
The primary way most people receive radio signals in valleys and ravines is by the signal reflecting off the stuff that is in the direct line of the
signal. Same as how the sun illuminating a ridge line will illuminate the valley below. There is light making it to the valley below, all be it
indirectly and at a far reduced level.
Like light, when ever radio waves travel through something, they are attenuated to some degree. Some things attenuate them very little, like air.
Some things attenuate them moderately, like dirt, or concrete, and wood. Some things are impervious to them and reflect them outright, that is
anything that is more than modernity conductive.
When you have a solid, or semisolid conductive surface, it will reflect the radio waves, and leave a shadow area behind it. Like if you hold a piece
of aluminum sheeting in front of a dish network dish.
In regard to dirt, concrete, and wood. As the frequency goes, up, the attenuation goes up. A 100mhz radio signal will pass through a 1 inch plank of
wood without much problem. A 12GHZ signal will not. A 1 mhz signal will pass through many feet of dry earth with no problem. A 100mhz signal will
The main thing that bothers isolated electronics is the part of the EMP that is in the upper frequency range of the EMP 1Ghz plus. And the only time
those components of the EMP will damage something is when they are in the 10 to 20+kv meter range.
Considering the point of origin is the sky directly over head. Since the maximum signal level of an EMP is 50kvm, the only time you will see signal
levels that can damage isolated equipment is if it is out in the open with no shielding over head at all. If you have a wooden frame structure over
head, it will attenuate the primary signal down to the point it won’t damage anything. Heck, tree limbs and leaves will attenuate RF signals to a
hefty degree. That is why VHF works better in heavy tree cover than 400mhz.
If you have a metal roof, then you will almost get zero incident signal. All you will detect is the signal reflected of the object around the house.
That signal will be orders of magnitude lower than that of the incident signal. No threat to anything.
If you are deep inside a concrete and metal. Building in a city, then nothing you have on you will be bothered by anything from an EMP.
If you have a metal frame storage building or shed with full metal siding on it. And you can’t receive your local FM station, and your cell phones
won’t work when the door is closed. (like many of my neighbors have) Then anything that is inside that building that isn’t connected to an outside
wire will be perfectly fine.
In regard to cars. When electronic engine controls first came out, they was pretty sensitive to outside electrical fields. That is because the
designers didn’t think through what they would be exposed to in the outside world. Things like 50KW broadcast stations and people running 1kw
transmitters in the car right next to them, or in the car it’s self had a tendency to render vehicles inoperable. The owner didn’t like that, and
gave the car companies an ear full. As a result, cars today have heavy shielding and filtering on all critical electronics to prevent them from being
bugged by a car beside them transmitting on a 1KW+ CB linear. Or even transmitting from the car it’s self.
In general, there is a big step from an electronic circuit being bugged by a signal to being damaged by it. If a car is not effected by a wide band
splatter box 1KW CB amplifier, then the signal level required to do it damage is quite substantial. And for most cars now in regular use, that
substantial level is beyond what an EMP can produce.