# Converting Radio waves into D.C Electrical energy (rf to dc)

Discussion in 'Wireless & RF Design' started by afm707, Oct 24, 2016.

1. ### hp1729 Well-Known Member

Nov 23, 2015
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Is this a correct schematic for the reference you posted?
Are component values critical? The final one about 100 nF? Would Germanium diodes be much different than Schottky?

At 0.5 uA (5 V w/ 10 M Ohm)
Germanium (1N270) = 0.100 V
Silicon (1N4148) = 0.180 V
Schottky (1N6263) = 0.100 V

Hmmm, not much difference.

Last edited: Nov 2, 2016
2. ### atferrari AAC Fanatic!

Jan 6, 2004
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Wasn't that in the past, considered ilegal?

3. ### ian field AAC Fanatic!

Oct 27, 2012
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Most of the multiple elements on a TV antenna are "directors" which make it as sensitive as possible in only one direction and practically deaf in any other.

Forget folded dipoles unless you live in the shadow of the transmitter - most RSGB/ARRL handbooks contain antenna design notes with diagrams where to put the feedpoint for voltage or current.

4. ### Threeneurons Member

Jul 12, 2016
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How far away ? 1.5V is just the voltage. Its not the power. How much current (amps, milliamps, microamps) ? What do you want to power ?

Basic electricity: Voltage is electrical pressure. Current (in amps) is the actual flow rate. Multiply the two, and you get the power you need.

I've tinkered with inductive power transfer. I made a lawn Xmas display years ago, called Propeller Santa. A stick with 32 LEDs on it that rotated to form an image. Since it spun, there could be no direct electrical connection. Power was transfered between two coils wound around ABS pipe.

Video:

Xmas Page:

Sinus23 and hp1729 like this.
5. ### tcmtech Distinguished Member

Nov 4, 2013
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Okay? I have no idea what you are after then.

You want to tap into radio waves and harvest their energy to get usable electrical power, IE electrical energy you don't have to pay for once you have the circuit working.
You just explained it yourself to yourself.

Uh, what? How would you describe taking ambient RF energy and converting it into usable low voltage DC power?

As others have explained as of present tech we can't tune into every frequency at once so at present we have to pick a specific frequency and tune into it to get anything workable for an output.

6. ### BR-549 AAC Fanatic!

Sep 22, 2013
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Who said he was harvesting ambient energy?

"i don't need free energy
just "Wireless Power Transmission"

Aug 21, 2008
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8. ### afm707 Thread Starter New Member

Oct 24, 2016
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i think i can not get current more than microamps
i need the maximum current of course

9. ### afm707 Thread Starter New Member

Oct 24, 2016
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i am sorry english is not my mother tongue

i think the free energy will be very small
i need to charge a battery as example

10. ### tcmtech Distinguished Member

Nov 4, 2013
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I think this thread need some basic clarification here.

First is,

Where do you want this 'Wireless energy' power to charge the battery to come from?

Second is,

How big is this battery and how fast do you want it to recharge?

11. ### tcmtech Distinguished Member

Nov 4, 2013
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Are the questions too hard or did the OP run away??

12. ### mohannatarajan New Member

Nov 24, 2016
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Maplin UK is selling a little kit for the price of less than 5 pounds.
Kit name: Power from space. Code:N11JG

13. ### ian field AAC Fanatic!

Oct 27, 2012
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There's an author who contributes micropower projects to various magazines - I think the name is Thomas Scarborough, possibly from S. Africa or somewhere like that.

Collecting RF energy isn't going to get you much further than charging a supercapacitor - unless you live in the shadow of a broadcast transmitter, or have a lot of time on your hands.

14. ### Alec_t Expert

Sep 17, 2013
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The shadow is precisely that; it will have very low level RF energy . Better to be in a major lobe of the radiation pattern.

15. ### ian field AAC Fanatic!

Oct 27, 2012
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Did you take lessons in deliberately misinterpreting what was said........................

Most broadcast transmitters don't have lobes - the whole point of broadcasting is to send the signal in *ALL* directions.

16. ### tcmtech Distinguished Member

Nov 4, 2013
2,808
2,705

I don't think he is the only one in this thread who took that 'How to misinterpret the obvious.' class.