[RE.Craig (OP)]

As most people with an interest in science will know. The crystal in a crystal radio generates an electrical current when it resonates with a radio wave. I know that the current of these devices are very low but nevertheless they produce it. But imagine for one moment for the ease of explanation that we had a crystal that produced .25 of a Watt when it received a signal from a transmitter outputting 1Kw / 1000 Watts. If we then had 4000 of these crystals they would be outputting collectively what they received, is this not so? But what would then happen if we arranged 8000 such crystals around our 1Kw transmitter? Would we not be generating 2Kw from an input of 1Kw meaning that we have achieved that "O" word that is forbidden in respectable science circles! I have in my deliberations considered such  things as Radio signal decay over inverse square law. It is perfectly possible to put Millions of crystals within the full 1Kw register of the transmitter. I am currently in the design phase of building a crystal generator with a 1Watt transmitter and 1500 1N34A Germanium diodes.
I would like to hear peoples opinions and ideas. 

[RD]

It is perfectly possible to put Millions of crystals within the full 1Kw register of the transmitter. I am currently in the design phase of building a crystal generator with a 1Watt transmitter and 1500 1N34A Germanium diodes.

A million diodes ! , I'm sure  Maplin / Radio-shack will love the idea , but you're wasting your time and money.

In an ideal world the best you could do was capture all of the energy transmitted.
In reality you won't achieve that.

It is most definitely impossible extract 2Kw from a 1Kw source ...
https://en.wikipedia.org/wiki/First_law_of_thermodynamics

[ don't you watch "The Simpsons" ?  [] ]


[ BTW you've got more than the inverse-square law to consider ... https://en.wikipedia.org/wiki/Attenuation#Radio ]

[CliffordK]

If you took a 100W light bulb, and surrounded it with solar cells.  You would expect the power picked up to be a fraction of the original power.  Say, if one had 10% efficient solar cells, then one would generate about 10W of power back from the 100W input.  And, everything behind the solar cells would be in shadow, so a second row of cells would be ineffective.

Likewise, your radio antennas absorb the EM energy that strikes them.  Surround the broadcast with enough antennas, and you will create some sort of a shadow.

So, like the theoretical solar panel experiment, you will be lucky to get a high fraction of the energy back out that you put in, but only with obscuring a large proportion of the initial broadcast.

Your local radio station won't be too happy if you build a Faraday cage around their broadcast tower.

[RE.Craig (OP)]

In 1936 there were over 3 million crystal radios in Greater London receiving their signal directly from the Bush House "London" transmitter. It's power output was a modest 100Kw. The collective output of those 3 million plus crystal radios was 123Kw. The BBC International World service Transmitter put out a massive 1000Kw signal. On the day Churchill announced the war, it is estimated that over 260 million people in Europe tuned into the broadcast from a single 100Kw transmitter in the centre of London. The signal was picked up by domestic crystal radio in the Falkland Islands and by the "Large Grid Ariel" project in Antarctica.  The point to remember is that Crystals do not "Absorb" or "Use" the energy they receive from the source, they are excited by it, unlike a modern radio "sucking the power from a set of batteries or the mains to power the amplifier. The energy collected by the amplifier is the electrical energy collected by the Ariel.
The main point's are1.The output of a transmitter is unaffected by the number of receivers collecting it.
2. The number of receivers have no effect on the transmitter even if their collective output is higher than that of the source.      
It could be described as a radio frequency inverter.   

[Bored chemist]

Are you sure about this
"The collective output of those 3 million plus crystal radios was 123Kw."
"The point to remember is that Crystals do not "Absorb" or "Use" the energy they receive from the source,"
Actually, that's exactly what they do.

"1.The output of a transmitter is unaffected by the number of receivers collecting it."
Oh yes it is. The effect is normally too small to observe but it's there.
"2 The number of receivers have no effect on the transmitter even if their collective output is higher than that of the source.   "
Oh yes they do. and the second clause is impossible if they are crystal sets..

[RD]

... over 3 million crystal radios in Greater London receiving their signal directly from the Bush House "London" transmitter. It's power output was a modest 100Kw. The collective output of those 3 million plus crystal radios was 123Kw.

Q. What is three million microwatts in Kilowatts ? ...

The sound power produced by the earphone of a crystal set comes solely from the radio station being received, via the radio waves picked up by the antenna. The power picked up by a receiving antenna decreases with the square of its distance from the radio transmitter. Even for a powerful commercial broadcasting station, if it is more than a few miles from the receiver the power received by the antenna is very small, typically measured in microwatts or nanowatts

https://en.wikipedia.org/wiki/Crystal_radio#Design

...  The collective output of those 3 million plus crystal radios was 123Kw.

Maybe 123W, rather than 123kW.

[RE.Craig (OP)]

If you took a 100W light bulb, and surrounded it with solar cells.  You would expect the power picked up to be a fraction of the original power.  Say, if one had 10% efficient solar cells, then one would generate about 10W of power back from the 100W input.  And, everything behind the solar cells would be in shadow, so a second row of cells would be ineffective.

Likewise, your radio antennas absorb the EM energy that strikes them.  Surround the broadcast with enough antennas, and you will create some sort of a shadow.

So, like the theoretical solar panel experiment, you will be lucky to get a high fraction of the energy back out that you put in, but only with obscuring a large proportion of the initial broadcast.

Your local radio station won't be too happy if you build a Faraday cage around their broadcast tower.

Your concept of a Faraday Cage is incorrect but visually similar to what Tesla built at Wardenclyffe Tower[A RADIO WAVE ELECTRICAL GENERATOR].
As I am sure you are well aware Clifford Radio Waves and Light waves are different beasts. Photons are absorbed by most surfaces whilst radio waves can pass through most surfaces or with wave guides, can be directed around or through them. As crystals generate their own current without robbing the source of their excitement of any of their energy it breaks no known laws of physics.
If crystal radios are to vague a reference, then think of the humble carbon microphone found in telephone receivers and cheap handheld Karaoke microphones.
These mic's have a layer of carbon sandwiched between to electrically conductive surfaces. Carbon is Piezoelectric, it generates a voltage when subject to physical pressure; even the pressure developed by a soft breath! A well designed 10mm carbon mic can generate a peak 16volts @ 40db. At the apex of the Royal Albert hall a speaker at 35db [speaking softly] can be heard at 40db at apex by clever design. I ask you this question. What power would by generated by that one person if the roof of the Royal Albert Hall were covered in said carbon mic,s? I have built two piezo acoustic generators for my bicycle lights and they work very well. I have also made one for a gardening friend were at night led's flash like fire flies among the foliage when the wind rustles the leaves.           

[CliffordK]

As I am sure you are well aware Clifford Radio Waves and Light waves are different beasts. Photons are absorbed by most surfaces whilst radio waves can pass through most surfaces or with wave guides, can be directed around or through them.

Radio waves, short waves, microwaves, IR, Light, UV, X-Rays, and Gamma Rays are all very much the same thing. 

The difference is that different materials absorb, reflect, or allow the signal to pass through them depending on the wavelength or frequency. 

In the case of your "crystal radio", there are a few key components.  The antenna receives (absorbs) the signal.  The larger the antenna, the greater a signal received (absorbed).

The crystal, or coil allows you to select the desired frequency.  This frequency selection may not be necessary if the goal was merely capturing energy.  However, one also rectifies the current with diodes, so perhaps one would get a benefit of frequency selection to multiple frequencies, then current rectification for each frequency.

To prove whether or not a signal is destroyed by an antenna.

Perhaps you could build an antenna like a mesh, long single strands.  I'd probably space the strands a couple of inches apart depending on the desired wavelength you are picking up.

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---------------
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Now bring another antenna behind this mesh antenna, with respect to the broadcast station.

You'll likely find a shadow, depending on the size of the antenna, and how close you are. 

As I was browsing, I did bump into the Nantenna concept.  The idea is that the EM waves in greatest abundance on Earth are in the visible light spectrum.  So, one could potentially pick them up in much the same was as a radio antenna.  However, it sounds like the design is still quite speculative.

[RE.Craig (OP)]

... over 3 million crystal radios in Greater London receiving their signal directly from the Bush House "London" transmitter. It's power output was a modest 100Kw. The collective output of those 3 million plus crystal radios was 123Kw.

Q. What is three million microwatts in Kilowatts ? ...

The sound power produced by the earphone of a crystal set comes solely from the radio station being received, via the radio waves picked up by the antenna. The power picked up by a receiving antenna decreases with the square of its distance from the radio transmitter. Even for a powerful commercial broadcasting station, if it is more than a few miles from the receiver the power received by the antenna is very small, typically measured in microwatts or nanowatts

https://en.wikipedia.org/wiki/Crystal_radio#Design

The arrangement of the diodes would be in close proximity of the transmitter/emitter. Even with my humble soldering techniques, I can probably fit a 1000 diode receiver it into a  240x190x90mm project box. I know others who could do a much tidier job in a smaller box but thirty years of diabetes has taken it's toll on my poor eyes :-'(. You also mentioned [as I did also] the small output of the crystals, but the output is only aided by the input of the long-wire ariel and not dependent on it. You would be surprised at the energy "up for grabs" in the air with a long-wire ariel. My new sw radio long-wire ariel has a surge protector fitted after my old radio [home made] blew it's vales during a vivid display of the northern lights. I live near 55* North. It is true that the more diodes that share an ariel the less they will collectively gain from it. But there are two simple solutions to this, increase the length of ariel available to each diode cluster or supply each diode with its own dedicated ariel.         

[RD]

Save your eyesight for a project which has a chance of success, the one you have described is a non-starter.

You would be surprised at the energy "up for grabs" in the air ...

Yes it is possible to harvest energy from ambient radio-waves, like this "hat" example which, according to the manufacturer, captures 50 microwatts when 2.5 miles away from the TV transmitter it is parasitising ... http://www.nytimes.com/2010/07/18/business/18novel.html?_r=0 

But the hat nor any other device can create or multiply energy : energy cannot be created or destroyed ... http://en.wikipedia.org/wiki/Conservation_of_energy

[RE.Craig (OP)]

As I am sure you are well aware Clifford Radio Waves and Light waves are different beasts. Photons are absorbed by most surfaces whilst radio waves can pass through most surfaces or with wave guides, can be directed around or through them.

Radio waves, short waves, microwaves, IR, Light, UV, X-Rays, and Gamma Rays are all very much the same thing. 

The difference is that different materials absorb, reflect, or allow the signal to pass through them depending on the wavelength or frequency. 

In the case of your "crystal radio", there are a few key components.  The antenna receives (absorbs) the signal.  The larger the antenna, the greater a signal received (absorbed).

The crystal, or coil allows you to select the desired frequency.  This frequency selection may not be necessary if the goal was merely capturing energy.  However, one also rectifies the current with diodes, so perhaps one would get a benefit of frequency selection to multiple frequencies, then current rectification for each frequency.

To prove whether or not a signal is destroyed by an antenna.

Perhaps you could build an antenna like a mesh, long single strands.  I'd probably space the strands a couple of inches apart depending on the desired wavelength you are picking up.

|  |  |  |  |  |  |
|  |  |  |  |  |  |
|  |  |  |  |  |  |
|  |  |  |  |  |  |
|  |  |  |  |  |  |
|  |  |  |  |  |  |
---------------
        |
        |
        |
        |

Now bring another antenna behind this mesh antenna, with respect to the broadcast station.

You'll likely find a shadow, depending on the size of the antenna, and how close you are. 

As I was browsing, I did bump into the Nantenna concept.  The idea is that the EM waves in greatest abundance on Earth are in the visible light spectrum.  So, one could potentially pick them up in much the same was as a radio antenna.  However, it sounds like the design is still quite speculative.

Hello again Clifford, may I call you " Cliff " ? I have carefully considered the Ariel-Antenna design and the "shadow" issue you have highlighted. Shadow is a problem if aerials are within very close proximity. TV aerials sharing a chimney are for instance usually within three feet of one another and can present shadow issues if they share the same axis; but moving the either the offending "shadow caster" or the ariel in shadow by a fraction of an inch off-axis will usually solve the issue. Common-sense intelligent  design can, I believe overcome any technical issue; It's what makes science so absorbing and enjoyable. If it were easy it wouldn't interest me! I like your ariel design, but feeding the collected current of so many poles into a single collector would cause to much resistance for what I need. I will in due course publish my build pictures to this site and let you know how I get along. I will publish the figures of the emitter output in Watts and the frequency used. I will publish the gain of the antenna [what do people prefer the American Antennaor British Ariel? ]and the outputted voltage and current of the receiver. I am however a bit reticent sharing the ariel/collector/ca unit design . If it were to work in any significant way I would like to patent it.             

[RE.Craig (OP)]

Save your eyesight for a project which has a chance of success, the one you have described is a non-starter.

You would be surprised at the energy "up for grabs" in the air ...

Yes it is possible to harvest energy from ambient radio-waves, like this "hat" example which, according to the manufacturer, captures 50 microwatts when 2.5 miles away from the TV transmitter it is parasitising ... http://www.nytimes.com/2010/07/18/business/18novel.html?_r=0 

But the hat nor any other device can create or multiply energy : energy cannot be created or destroyed ... http://en.wikipedia.org/wiki/Conservation_of_energy

Some interesting and can I say curtcomments RD you cheeky boy!, but let me address them.
 The idea that a radio diode is parasitic is not in any manner correct. If a device were truly parasitic it would draw and rob energy from the emitter. This is not the case with any radio diode as they are merely excited by the presence of a frequency they are attuned to, their harmonic frequency. It is the harmonic frequency, the resonance of the crystal that generates an internal piezo voltage within the crystal lattice.
They generate a voltage in the presence of a radio wave they are attuned to. There is no limit to the number of crystals one can have in the presence of an emitter. The numbers of radio diodes receiving and generating voltages have no effect of the emitter whatsoever!. The output of said radio diodes can collectively not independently generate more energy than the emitter that they passively gained from.         

[RE.Craig (OP)]

Are you sure about this
"The collective output of those 3 million plus crystal radios was 123Kw."
"The point to remember is that Crystals do not "Absorb" or "Use" the energy they receive from the source,"
Actually, that's exactly what they do.

"1.The output of a transmitter is unaffected by the number of receivers collecting it."
Oh yes it is. The effect is normally too small to observe but it's there.
"2 The number of receivers have no effect on the transmitter even if their collective output is higher than that of the source.   "
Oh yes they do. and the second clause is impossible if they are crystal sets..

Hi Bored Chemist, I look forward to proving you incorrect on all counts  .

[RD]

Some interesting and can I say curtcomments RD

I prefer "concise" rather than "curt". I'm doing you a favour if I can deter you from proceeding with this doomed endeavour.

The idea that a radio diode is parasitic is not in any manner correct. If a device were truly parasitic it would draw and rob energy from the emitter.

Maybe I should have described the hat device as a scavenger rather than parasite,
 but nevertheless you're still flogging a Findus lasagne (dead horse).

The technical details don't matter : it's fundamentally impossible to manufacture energy.

IMO the "over-unity" brigade are either barking misguided or con-artists ... http://rationalwiki.org/wiki/Over_unity

[CliffordK]

There have, in fact, been several ideas to transmit wireless power, beginning with the time of Nikola Tesla.

Although, people worry about EM radiation from things like cell phones now.  Living in a Tesla wireless energy world might give one great cause for concern.

Here is a great HowStuffWorks article on several wireless energy transfer methods.

[bizerl]

what do people prefer the American Antennaor British Ariel?           

I don't think it will work if you're using mermaids  []. Maybe an Aerial would be more helpful. Which ever you use though, I don't understand how the radio waves can interact with a receiver enough to "excite" it, without diminishing themselves in some way. If they passed through the receiver uninterrupted and undiminished, then by definition (and I'm aware it's my definition) the receiver won't be "interrupted" either.

So the radio waves have to "excite" the receiver enough to generate an output, without imparting any of its energy? How does this happen?

[CliffordK]

The point is that if a radio shadow exists, even if it isn't a large area, that means that the antenna is actually interacting with the radio waves, likely in a destructive fashion by absorbing them.  So, row after row of people aren't passively picking up the same radio waves.

But, it never hurts to try an experiment, especially if the goal is just to better understand the phenomenon.

[Bored chemist]

Are you sure about this
"The collective output of those 3 million plus crystal radios was 123Kw."
"The point to remember is that Crystals do not "Absorb" or "Use" the energy they receive from the source,"
Actually, that's exactly what they do.

"1.The output of a transmitter is unaffected by the number of receivers collecting it."
Oh yes it is. The effect is normally too small to observe but it's there.
"2 The number of receivers have no effect on the transmitter even if their collective output is higher than that of the source.   "
Oh yes they do. and the second clause is impossible if they are crystal sets..

Hi Bored Chemist, I look forward to proving you incorrect on all counts  .

Sorry, but I'm willing to bet that you won't prove me wrong on any of those counts.
I won't insult you with a sum of money because, if you could get this to work, you would have solved all the world's energy problems (and thereby most of its other problems) so you would have all the money you could need an then some.

However, I'd strongly advise that you don't waste your time trying.
Find someone who knows about antenna design and ask them what they think.
When they stop laughing they will probably offer the same advice.

BTW, RD and I might be "curt" but reality is really rude: when it slaps you down there's no forgiveness there.

[bsharp]

I had this same idea a couple years ago. The idea was to constantly charge a battery for small devices like a cell phone, flashlight, ect. A friend and I were brain storming ideas of ways to power spacecraft. Although the fact that power cannot be created or destroyed is as far as we know it true. The world and the universe is filled with it. It has to be otherwise there would be absolutely nothing here. Here on earth there is a barrage of EM waves created from everything from all sorts of things like your automobiles ignition system to the neighbors boys toy car to cell phone's and broadcast signals. We are extremely wasteful creatures. The signals are not just all from us! All you need to do is fire up an old dial type radio and turn the knob and you will find static, buzz and squealing between your channels. Some of this noise is from the universe. The universe is filled with EM radiation from over 4 billion years of stars churning, exploding, planets, stars and black holes singing. This is energy and it is free and will be for the life time of the cosmos. No tax can be placed on it. We live in a soup of energy. All we have to do is pick it up and use it.
Even more simple than a solar cell one could gather radio waves and collect the energy from it. Not just one specific frequency but multiple thousands of them at once.
It is easy to say that power from a tiny radio tower would not be sufficient but how about also including the em waves from the sun and the black hole at the center of our galaxy? Now it gets much more interesting.
So if we constructed a small analog receiver that would search for the strongest thousand bands of static and simply convert that to battery power. It would collect energy continuously for the lifetime of the universe. It would be a small amount of power per frame of time but if collected and used efficiently it would be an indefinite collector of the power of the universe. I am not saying that the construction of the device would be an easy task as portions would need to be constructed in the sub micron scale. But if one could construct such a device that could power even a small processor for short periods of time it would be an innovation.
The trouble with innovating something is the need to imagine and create something that has never been done before. Anything else is just doing things the way we have always done them.                   

[syhprum]

If any correspondents contemplate doing research with "crystal radio" they should bear in mind they are a prodigious source of intermodulation interference as I found during the war when receiving the 600KW world service transmitter from about 20 miles away on my very unselective receiver.