Wire and Cable Technology Blog

A lot of what Tesla did so many years back gets muddled and confused over time. Tesla's demonstration of wireless distribution of power over 25 miles did work at lighting a group of fluorescent bulbs. However, I don't remember anybody claiming that this was an efficient transfer of power. But the referred article does mention the real stake in the heart of this technique. Without a way to measure how much power an individual was using, proper billing could not happen. This technique did later get used for a host of communication basics, we now call it radio.

Redfred

I forgot to add to your input that electricty users near HighPower LF and MF transmitters can and have used this power to light flourescent tubes. I believe that these folk were said to have been threatened with prosecution for stealing electricty!

Sleepy

A lightning bolt sure transmits a lot of power.

Indeed and it's wonderfully safe and controllable...<slaps furry head with passing rodent>
Del

Well... that part still needs a little work, but, in theory.

Well maybe it would be more helpful if someone would calculate the energy in microwave that would have to be transmitted, and then calculate the exposure to microwave energy that is seriously dangerous.

Sure we can get energy from solar collectors in space to a land based receiver, but we cook everything on that side of the planet.

The major problem with wireless transmission of electricity, is the the energy requirement to power anything useful is enormous. Consider that Tesla was talking about a transmitter system that would charge the entire earth and it's atmosphere. Not to mention the disruption of all radio transmissions.

As to the the "beaming" of power from space, that is a disaster looking for a ground zero. If the projector becomes misaligned even for a second it would destroy any thing in it's path. Think of your microwave at a million times it's current power level. Any electromagnetic radiation at mega-watt level is deadly to life.

Dragon

Dragonsfarm,

I completely agree with your comments regarding the transmission of power from Sun to satellite DC power, generating efficient power through Magnetrons and with very precisely shaped antennas to send thepower, usually at around 2400 MHz to antenna farms on the earth surface.

Safety is paramount on anything like this and we just do not need to be microwaved.

Maybe we have to move underground!

Has anybody got access to the original 1980 model calculations; they were quite interesting and you can then use the models to look at just how the energy levels, does or does not fall off with distance fom the centre.

Auto shut off of the system is of paramount importance if the beam moves off centre.

Sleepy

Sleepy & Dragonsfarm,

Sleepy inadvertently included the dominant flaw in this approach in his comment. Putting a power gathering system in space that must be shut down when misdirected because of the damage that can be done, means that this is a space based weapon. This breaks the space weapons treaty. It will be immediately destroyed upon deployment, long before any testing will be possible.

I know that you meant well and that a weapon was not your goal. But this will not fly.

Redfred,

A wonderful answer, I was fighting this dream (nightmare) in the1980 time frame but I never had that beautiful thought!!

Brilliant, thanks, I might be able to sleep now!!

Sleepy

Its a conspiracy.

We actually know how to do it but we are keeping it secret since the old method keeps us all employed.

For a variety of reasons, large wattage wireless power transmission will not work. But I know that it has been done for some very small power applications. How often have we wired a circuit only to find the pesky 60/50 hertz power signal coupled into our circuitry. It's an extremely inefficient coupling so very little power is available. Also it varies constantly in magnitude but it is always there. Some of today's circuitry though can stay alive on microwatts of power with brief bursts of milliwatts required for computation and/or other purposes. Careful planning needs to be done to acquire this parasitic power and to sense when enough had been stored for the next calculation burst. But nothing prevents an engineer from using this. The question is though what type of circuit could use this low power source. The circuits that require the smallest amount of power come under the heading of signal or data acquisition.

I know of an application where this has already been done. Many roof top television antennas (a slowly dieing breed, but their not dead yet ) have a preamplifier mounted as part of the antenna array. This amplifier "steals" the local power hum to drive the broadband received RF power down the twin lead or coaxial cable. Typically the added noise of the amplifier is minuscule compared to the signal to noise improvement by having a stronger signal at the receiver.

Redfred,

Rooftop antennas, antennae? a dying breed???

Now why did I not thnk of that before I put up a farm on my roof this year providing multi channnel digital TV, DAB radio, FM radio, Analog TV etc, etc

All being distributed to 9 or 10 rooms by CABLE, including study and garage/workshop. Still two cables to run!

Just think of the money that I would have saved if I had had a reasonable signal strength on these Essex Marshes!!

Sleepy

Yahoo search "Rectennas" idea's been around for a while, just not economically practical.

"... And, now, there's a company proposing to collect solar power and use microwaves to transmit it down to Earth..."

Don't dare to pass under (not even close to) this microwave beam... ... It will be very hot... ... ...

Such EM fields (able to transfer such huge amounts of electrical power) will have huge (RF) power. We feel unsafe with the tiny power (tens of mW) of the cellphones. How would you feel by knowing that EM fields with huge power (KW) exist around you???

I don't think that such a concept will ever work for high energy transfer (like distribution networks). Maybe, it could work only for powering small devices (in a distance of just few meters) with very small power demands. Nevertheless, I doubt even for this.