Help me start a project on RF Energy Harvesting

[Pulkit Varshney]

Hello,, i want to work on a project on rf energy harvesting . Can anybody tell me from where should i start ,like what should be starting studies, which type of antenna should i use,etc. ?

 

[WimRFP]

Re: RF Energy Harvesting

Hello,

You should start with basic EM and antenna theory. You should know things as: power flux density (E*H), E- field strength, field attenuation versus distance, ERP, EIRP, antenna aperture, relation between antenna aperture and gain, relation between gain, size and vert & hor. beam width, polarization, LOS propagation, maybe propagation over ground (two ray model), etc.

The above enables you to figure out how much power you can extract from the environment.

Next step is to understand the diode detection (rectifying) process, rectifier topologies and losses in LC or transmission line circuits. As the output power of the antenna may be very low, you need to transform the antenna's output impedance in such a value that you have sufficient voltage to have good detection performance (but don't stress the diodes too much). You also need to know the properties of diodes to make the best match and to avoid temporary overload (as this may fry your HF schottky rectifiers).

Once you have some power available, you need to design a good converter that enables you to convert the rectified power into the desired voltage, without much loss.

You may also need band pass filtering in the RF section to avoid that harmonics due to the rectifiers reradiate into the air.

Things that will have large influence on the work to be done: wide band versus narrow band, center of frequency band and omnidirectional versus spot. If you have one strong transmitter, then a narrow band, spot approach may work best (and is relatively simple).

 

[DDavid]

Hi

Its very nice and "sexy" idea...
I am in personally did something like that but not from air but from unused RF at RF BOARD... and used with this energy again at the same system to different application...
In my opinion u need to focus is how to match diode etc
of course how to "collect" the RF...

Regards and GOOD LUCK
David

 

[Nick C.]

 

[xaccto]

^ don't you just luv how he says he smells BS, lol :razz:

google for Texas Instruments bqTESLA150LP Evaluation Kit

I might end up getting that, but in meanwhile I am persisting with some of my own experiments.
Tesla claimed high efficiency of energy transfer.....I'm yet to see better than inverse square law.
I would like wireless energy transfer of at least 10cm (so placement is not needing to be accurate)
In the end, may have to settle for very close.......which then its really energy transfer by induction isn't it?
Like a air coil inductor......
I'm gonna wind a pancake coil next....when i'm sufficiently bored to get round to doing it...

anyway its interesting there are others on this board interested in this energy harvesting topic

 

[keith1200rs]

Unfortunately, as in an earlier thread: https://www.edaboard.com/threads/175923/ people seem to think the laws of physics don't apply to them.

I like the video but some people will still ignore the simple facts.

Keith

 

[DDavid]

of course the movie is correct, in order to reuse this energy u need to "catch" watts ...
when i built it i used with unwanted rf energy (at my board), and I am talking about a 10 watts at least and than I used with this in order to turn on fans...
so of course eff is very low...

 

[FvM]

Some contributions are referring to wireless power transfer rather than RF energy harvesting. In my opinion, this is a different topic.

Energy harvesting is bound to expectable enviromental RF power densities and ends up in µW, at maximum a few mW utilized power in special cases.

RF power transmission in contrast is actively distributing electrical energy. Practical limitations are set of course by EMC and safety regulations, and generally efficiency reasons. RF power transmission, at least for proximity and vicinity, is investigated by the industry
Wireless Power Consortium - Creating the Standard for Wireless Charging - Wireless Power Consortium

For general wireless energy transfer options, see Wireless energy transfer - Wikipedia, the free encyclopedia

 

[davenn]

of course the movie is correct, in order to reuse this energy u need to "catch" watts ...
when i built it i used with unwanted rf energy (at my board), and I am talking about a 10 watts at least and than I used with this in order to turn on fans...
so of course eff is very low...

of course you realise that you are not going to recover at least 10 watts unless your system is sitting right beside a major transmitting tower ( radio/TV) ?
the best you will do in the avg home would be a few microwatts or so. "ye canne break the laws of physics", as Scotty from Star Trek would say

cheers
Dave