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Building a rectenna...


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#1 Boerseun

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Posted 24 April 2006 - 05:43 AM

Yes, I'm bored.

But I've got a way out of boredom!

I want to build a rectenna, something that can convert microwave radiation into usable DC. How on earth do I do this? I've surfed the net, but could find no useful diagrams or anything. Even Wiki only says what it is, but no schematics or diagrams.

Then, as a second part to this anti-boredom project, I want to construct something that can focus microwave radiation. I've read that there are certain screens you can construct from left-handed metamaterials that will bend and focus microwave energy. This means absolutely nothing to me.

Can anybody help me with a circuit diagram for a rectenna, plus whatever the best materials might be to construct the receiving mesh with? And a microwave focusing device? Your help would be much appreciated, and would go quite a ways of saving me from a boredom-related death.

#2 Jay-qu

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Posted 24 April 2006 - 06:28 AM

I to found info on this topic fairly sparse.. wiki did give a very run down, something bout a schottky diode between the antenna diodes..
as for focusing the micowaves could you not just find a material that reflects microwaves and construct a dish out of it?

#3 Racoon

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Posted 24 April 2006 - 10:22 AM

I want to build a rectenna, something that can convert microwave radiation into usable DC. How on earth do I do this? I've surfed the net, but could find no useful diagrams or anything. Even Wiki only says what it is, but no schematics or diagrams.

Then, as a second part to this anti-boredom project, I want to construct something that can focus microwave radiation. I've read that there are certain screens you can construct from left-handed metamaterials that will bend and focus microwave energy. This means absolutely nothing to me.


I thought the title of this thread was something else! :confused: :naughty:

I have some hyper-dimensional conversion flow anti-materials, Boerseun :naughty:
;Aquired through a project construction along the same vein as yours...

These anti-materials do bend and focus radiation rectally.
I'll see if I can dig up some old schematics. :shrug:

#4 Pyrotex

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Posted 24 April 2006 - 11:59 AM

I thought the title of this thread was something else! ...These anti-materials do bend and focus radiation rectally...


"Use the Rectum, Luke!"

From the blockbuster movie, "Star Privies"

#5 Turtle

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Posted 24 April 2006 - 12:30 PM

Then, as a second part to this anti-boredom project, I want to construct something that can focus microwave radiation. I've read that there are certain screens you can construct from left-handed metamaterials that will bend and focus microwave energy.
Can anybody help me with a circuit diagram for a rectenna, plus whatever the best materials might be to construct the receiving mesh with? And a microwave focusing device? Your help would be much appreciated, and would go quite a ways of saving me from a boredom-related death.


The dish is for receiving only; what you need my friend for transmitting microwaves is a good ol' waveguide. Here's a Wicky to start your ticky:
http://en.wikipedia.org/wiki/Waveguide
Use caution around unshielded cavity magnetrons (microwave makers:eek2: ). There is a danger of burns as well as disorientation from exposure. :confused:

#6 Boerseun

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Posted 24 April 2006 - 12:39 PM

The dish is for receiving only; what you need my friend for transmitting microwaves is a good ol' waveguide. Here's a Wicky to start your ticky:
http://en.wikipedia.org/wiki/Waveguide
Use caution around unshielded cavity magnetrons (microwave makers:eek2: ). There is a danger of burns as well as disorientation from exposure. :confused:

Thanks, Turtle - but I'm not too stressed about generating the waves as yet.
The biggest thing I can't seem to get much info on is on how to focus the energy. What I need for this specific project is something that can focus the energy as it passed through it, much like a lens will focus visible light.

#7 Turtle

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Posted 24 April 2006 - 12:59 PM

Thanks, Turtle - but I'm not too stressed about generating the waves as yet.
The biggest thing I can't seem to get much info on is on how to focus the energy. What I need for this specific project is something that can focus the energy as it passed through it, much like a lens will focus visible light.


The focussing on the receiving end is acomplished with a parabolic dish, which focusses the incoming microwave signal by reflection onto a tuned receiving head located at the parabola's focus.
This goes from here to radio technology & electronic circuitry which is beyond me in the specifics of turning the received signal to usable power. The incoming signal however has to have a lot of power to begin with if any is expected for recovery.
I understand this type of technology is proposed as an energy source for Earth, wherein solar powered satellites genrate high power microwave beams which get aimed at receiving stations on Earth where the signal is transformed back to usable electricity.
Keep us posted if ya don't get roasted.:eek2: :singer:

#8 Boerseun

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Posted 24 April 2006 - 01:52 PM

The focussing on the receiving end is acomplished with a parabolic dish, which focusses the incoming microwave signal by reflection onto a tuned receiving head located at the parabola's focus.
This goes from here to radio technology & electronic circuitry which is beyond me in the specifics of turning the received signal to usable power. The incoming signal however has to have a lot of power to begin with if any is expected for recovery.
I understand this type of technology is proposed as an energy source for Earth, wherein solar powered satellites genrate high power microwave beams which get aimed at receiving stations on Earth where the signal is transformed back to usable electricity.
Keep us posted if ya don't get roasted.:eek2: :singer:

Yes... but for this specific project, the radiation must pass through the focusing device.

The parabolic dish reflects, focusing it on the receptor like a satellite dish would. I want to know how to do to microwaves what a lens does to light.
They're both electromagnetic radiation, just different wavelengths. I expect the material needed will be quite extraordinary due to the specific wavelength of microwave radiation, but I want to know what the material would be?

#9 Turtle

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Posted 24 April 2006 - 04:02 PM

Yes... but for this specific project, the radiation must pass through the focusing device.

The parabolic dish reflects, focusing it on the receptor like a satellite dish would. I want to know how to do to microwaves what a lens does to light.
They're both electromagnetic radiation, just different wavelengths. I expect the material needed will be quite extraordinary due to the specific wavelength of microwave radiation, but I want to know what the material would be?


Mmmmm...I know they use long tubular nested high incidence mirrors to focus X-rays in the X-ray space telescope(s). Still, I don't see why you want radiation passing through? If it's a matter of direction (you don't like the 180 change of the dish?), an arrangement of 2tuned dishes should output in the same direction as input.
Tuning the dishes require deciding where you want the final beam to fall with greatest intensity, & then constructing a parabola with that point as the focus.(That's your dish template) I suppose if you want variable distance/range, you will need a flexible parabolic dish & then you may have something challenging to build.
Goin' hunting with this thing or what?:singer:

#10 alexander

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Posted 24 April 2006 - 05:59 PM

there was a guy at last year's hope conference who was building if i am not mistaken an ion cannon out of a microwave tube.... need to do more research, i'll post what i can find later if you are interested...

#11 C1ay

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Posted 24 April 2006 - 07:28 PM

Yes... but for this specific project, the radiation must pass through the focusing device.

It sounds like you are describing a horn antenna. There is also a conical form popular in the communications industry. Any conductive metal will function for these but the higher the frequency, the higher the requirement for surface accuracy. If using a mesh the openings should be smaller than 1/10th of a wavelength. Either design type can concentrate the energy into a waveguide for futher processing or use.

#12 becklectic

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Posted 24 March 2009 - 02:10 PM

Check this out... Fig 5.

http://nutsvolts.tex...s/200503/?pg=27

Replace the hyphens with backslashes.

#13 erich

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Posted 28 July 2010 - 09:48 AM

Black Swan Solar Technology Emerges

Scientists from the United States, Belgium and Korea are developing a new and novel approach for collecting and converting solar energy to DC output, which makes possible the design and fabrication of a new class of solar energy converters. This breakthrough science offers the potential for a dramatic increase in energy conversion efficiency and cost savings compared to current solar cells

The technology is based on a unique "optical rectification"
Efficiencies as high as 50% were recorded.

EnegyCentral.com

See guys ...I do have other interest than Biochar
Cheers,
Erich

#14 andrew.68w

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Posted 19 December 2011 - 04:35 PM

Ok I came across your original post on a search of my own for rectennas, I was actually looking for parts. I have here this link that I hope will help you out: http://upcommons.upc...ranco_FINAL.pdf . Just out of curiosity are you planning some sort of SBSP demo.