The AM Forum

I found this to be interesting but I don't know if backscatter is what it should be called? I haven't taken the time to look up the words and see how broadly they apply but none the less, a sign of thing to come and the video is very interesting to me.

http://techbeat.com/2013/08/ambient-backscatter-harvesting-power-from-thin-air/ (http://techbeat.com/2013/08/ambient-backscatter-harvesting-power-from-thin-air/)

So.......That's where my backscatter signal is going....power thieves!

I've charged batteries with your backscatter signal.

Yea, dumb names. Work on power harvesting from ambient RF has been going on for many years. The computer weenies act like it's something new.

Steve, any links on older power harvesting schemes?  Always wondered about this, along the lines of, give me enough crystal radios, and I'll power the world's largest joy buzzer.  Really though, now that millions, billions, of nano diodes could be stuck on the head of pin, probably grown on fabric, aerosolized for goodness sake, seems like sort maybe kinda.

quantum antenna. log periodic for ambient radiation. The rectifiers have been the problem.

The rectenna was invented in mid-60s.

RF power harvesting is more reasonable now because electronics and computing requires less power.

Try search terms like "power harvesting", RF, patent, "energy harvesting". You'll get tons of hits. I recall first hearing about this sort of thing in the early 2000s but I'm sure the idea goes way back, like many decades.

"Free" power approaches abound lately, like power from motion, key presses, mouse movement and so on (piezoelectric and magnetic) and kinetic (actually pretty old - used in wrist watches for a long time) , temperature changes (pyroelectric effect), of course solar (photovoltaics), thermal gradients/thermoelectric, etc. Many of these are not new. The buzz is about new ways of using them or more efficient implementations.

Free power harvesting was proposed and demonstrated by Nikola Tesla over a hundred years ago. Was granted a number of patents in this area.

I believe Tesla was the first one to suggest the wireless transmission of power.

Yes, wireless transmission of power and harvest of ambient RF - two different things.

Might have been in Pop Electronics some years ago.  Excess Rf power for your crystal set and transistor AF amp. ;D

Did a quick search of the PopTronics info I have and didn't find anything.  Might have been in an issue I don't have access to or maybe in Electronics Illustrated or another mag of the time.  In any event, it seems that I remember something like this in a 50's or 60's issue of one of the mags of the day.  Basically used 2 diodes off of the tuned circuit; one as an AM detector and the other as a power supply diode to power a 1-transistor audio amp.  Only difference in the outputs of the 2 diodes was the filtering to either make audio or DC.  Worked on really strong signals that had enough RF to make the DC power.

"Harvesting RF power"?

Duh....

ever listen to radio?



Of course if you don't want to listen, use the rectified RF to charge batteries.

no magic in that.... people have been doing it for years...

Takes no special equipment....

An antenna, coil and diode.
 

My, my, a whole new area for litigation.
"Hey, your thieving my RF for non-intended application."
..Or
"For only pennies per day, you too can have a license to receive my RF for power purposes."
Of course, you'll have to sign an agreement that you won't try to decode the signal for commercial or other heinous purposes. Um hmm.

An explosion of thoughts and applications.--

  Bring back much higher powered analog TV.  Sell power to make up the diff. In costs for retroverting from digital.

Lets try the self powered radio app. again.  What with 3.3 volt devices having much less current draw than those antiquated germanium xistors, we ought to be able to power a full blown DDC SDR.

Did y'all notice that the dipoles were about 12 inch half waves?

Slammin' and jammin' anyone?
Pass some neat disrupting or redirecting virii along with your power signal.?  Encode your RF to make slaves of thieving devices.   Track, control, you name it.  Whole new realm for satellites, cell towers and emongus TV/FM towers.

...and on and on.

No way can you have all good without some bad.

Pushback by battery manufacturers or collusion?