Scavenging ambient electromagnetic energy

Daox · 07-12-11, 07:36 AM

Interesting quick read. I'm surprised to see MIT working on this. Its been known for quite some time that you can collect small (quite small) amounts of power with antennas. Perhaps their wide band antenna can collect a sizable amount?

Scavenging ambient electromagnetic energy - Hack a Day

Piwoslaw · 07-12-11, 12:43 PM

Way cool! My neighbors are going to love me when I start sucking up the TV and wireless signals from the whole neighborhood

Seriously, would harnessing this energy be noticeable (weaker signal locally)? Or is it just energy which would be wasted anyway?

Daox · 07-12-11, 01:23 PM

The antenna would basically block/absorb any signal that hits it I think.

Xringer · 07-12-11, 02:07 PM

One winter back around 1962, I lived on my grandfather's farm.
There was a barbed-wire next to the road, underneath the power lines.
I'm not sure how long the fence run was, but the top wire would zap you sometimes.
I always wanted to hook up to it and run a transistor radio.
But, all we had on the farm was a big old tube radio.

Because of the losses incurred using a small antenna and by distance,
Inverse Square Law

The amount of power you could harvest is pretty meager.
You might be able to run some very small devices.

People who live close to high powered transmitter sites,
might be able to power some small LED lamps etc, given enough antenna capture area.

AC_Hacker · 07-12-11, 04:31 PM

Quote:

Originally Posted by Xringer

The amount of power you could harvest is pretty meager.

Ditto that.

Seems to me that energy spent EcoRenovating will give a much better yield.

-AC_Hacker

Daox · 07-12-11, 04:56 PM

Thats exactly why I was surprised that MIT was even looking into the idea...

Xringer · 07-12-11, 05:29 PM

Quote:

Originally Posted by Daox

Thats exactly why I was surprised that MIT was even looking into the idea...

I didn't read the whole story, but my guess is, they want to power
some extremely small devices, that don't need much power.
But they need it over a long period of time.

The Russians planted many of their bugs with a LOT of batteries.
But, any bug that's self-powered is going to be long lasting..

The Russians installed large reflectors inside our consulate in Moscow,
then bounced hi-powered microwaves off them.
If someone was taking nearby, the soundwaves would modulate the reflector,
and the microwave return..

strider3700 · 07-12-11, 11:02 PM

If I key up my HF radio at anything over 50 watts my wifes touch sensitive night light will turn on as if it was touched. the antenna wire would probably be about 15' away from the light at it's closest point. the radio isn't powering the light but it is enough power to confuse the little touch sensor somehow.

Quest · 07-13-11, 10:14 AM

done something similar back in my teen days:

While building crystal radio sets, we experiemented with a large spiderweb antenna and an air-gap condenser (standard 1-gang, 365pF) and handful of 1N60 rectifiers and a some electrolytic capacitors, I made a big tuned antenna trap to capture the loudest (contains the biggest signal from nearby AM broadcast) broadcast station, rectify it and use it as a DC power source to feed my little 1 (or was it 2) stage Germanium transistor gain stage for the second Xtal radio set up, so that I can use a speaker to listen to broadcast with amplification as opposed to a earpiece.

That was fun times... I still miss it.

Q.

(** Now, with solar cells so cheep, I'd rather concentrate my effort on cheep solar cell panels, cheep NiMH rechargeables to build stuff instead of doing something aforementioned...**smiles**)

07-12-11, 07:36 AM	#1
Daox Administrator Join Date: Aug 2008 Location: Germantown, WI Posts: 5,525 Thanks: 1,162 Thanked 374 Times in 305 Posts	Scavenging ambient electromagnetic energy Interesting quick read. I'm surprised to see MIT working on this. Its been known for quite some time that you can collect small (quite small) amounts of power with antennas. Perhaps their wide band antenna can collect a sizable amount? Scavenging ambient electromagnetic energy - Hack a Day __________________ Current project - To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. & To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

07-12-11, 12:43 PM	#2
Piwoslaw Super Moderator Join Date: May 2009 Location: Warsaw, Poland Posts: 961 Thanks: 188 Thanked 110 Times in 86 Posts	Way cool! My neighbors are going to love me when I start sucking up the TV and wireless signals from the whole neighborhood Seriously, would harnessing this energy be noticeable (weaker signal locally)? Or is it just energy which would be wasted anyway? __________________ Ecorenovation - the bottomless piggy bank that tries to tame the energy hog.

07-12-11, 01:23 PM	#3
Daox Administrator Join Date: Aug 2008 Location: Germantown, WI Posts: 5,525 Thanks: 1,162 Thanked 374 Times in 305 Posts	The antenna would basically block/absorb any signal that hits it I think. __________________ Current project - To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. & To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

07-12-11, 04:56 PM	#6
Daox Administrator Join Date: Aug 2008 Location: Germantown, WI Posts: 5,525 Thanks: 1,162 Thanked 374 Times in 305 Posts	Thats exactly why I was surprised that MIT was even looking into the idea... __________________ Current project - To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. & To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

07-12-11, 02:07 PM	#4
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 114 Thanked 250 Times in 230 Posts	One winter back around 1962, I lived on my grandfather's farm. There was a barbed-wire next to the road, underneath the power lines. I'm not sure how long the fence run was, but the top wire would zap you sometimes. I always wanted to hook up to it and run a transistor radio. But, all we had on the farm was a big old tube radio. Because of the losses incurred using a small antenna and by distance, Inverse Square Law The amount of power you could harvest is pretty meager. You might be able to run some very small devices. People who live close to high powered transmitter sites, might be able to power some small LED lamps etc, given enough antenna capture area.

07-12-11, 11:02 PM	#8
strider3700 Master EcoRenovator Join Date: Dec 2008 Location: Vancouver Island BC Posts: 745 Thanks: 23 Thanked 37 Times in 30 Posts	If I key up my HF radio at anything over 50 watts my wifes touch sensitive night light will turn on as if it was touched. the antenna wire would probably be about 15' away from the light at it's closest point. the radio isn't powering the light but it is enough power to confuse the little touch sensor somehow.

07-13-11, 10:14 AM	#9
Quest Apprentice EcoRenovator Join Date: Feb 2011 Location: Canada Posts: 109 Thanks: 13 Thanked 13 Times in 11 Posts	done something similar back in my teen days: While building crystal radio sets, we experiemented with a large spiderweb antenna and an air-gap condenser (standard 1-gang, 365pF) and handful of 1N60 rectifiers and a some electrolytic capacitors, I made a big tuned antenna trap to capture the loudest (contains the biggest signal from nearby AM broadcast) broadcast station, rectify it and use it as a DC power source to feed my little 1 (or was it 2) stage Germanium transistor gain stage for the second Xtal radio set up, so that I can use a speaker to listen to broadcast with amplification as opposed to a earpiece. That was fun times... I still miss it. Q. ( Now, with solar cells so cheep, I'd rather concentrate my effort on cheep solar cell panels, cheep NiMH rechargeables to build stuff instead of doing something aforementioned...smiles**)