Design of a Battery-free Wireless Sensor Node
In my MSc thesis I have developed a passive wireless sensor node that harvests the energy it needs from a nearby RF power source (basically just like passive RFID tags do).
I would like to share this with you
Main characteristics: battery-free, ASK demodulator, backscatter demodulator, a general-purpose microcontroller (MPS430F2132), range of 4.1 meters (using a custom-designed dipole antenna)
You can check out everything (schematics, simulation models, PCB layout, etc...) at my website: http://r12624.pt.vu
I hope it helps you in your projects
Best regards
Hi, a good quality project.
can i ask you about the power of the output of the source ?
Sure, the transmitter antenna was set to radiate 2Werp @ 866.6MHz (you can see the radio regulations here: RFID-Handbook - RFID-Frequencies).
In the ADS model of the circuit, the load was replaced with a DC current generator of 5uA.
why? how did you calculate it ?
tanks :)
5uA is the amount of current that the sensor node consumes while sleeping (this value corresponds to the sum of the quiescent currents, and was based on datasheet information)
by the way, feel free to ask more questions
great,
now what about feasibility of a system that harvest power from TV signals ?
Check this: www.media.mit.edu/~jrs/WISP-WARP.pdf
thanks,
so, in the case of TV signal, witch antenna is the most suitable ? Yagi ?
in first stage, i am planing to prototype the system, can i use typical components (not SMD ones) ?
thanks in advance :)
In the case of a TV signal I would say the best antenna would have a high gain and a bandwidth large enough to cover the intended frequency band
Regarding the components, I think you will have to use SMD parts because typical components are hard to find
Also, I would advise you to take into account the copper lines that connect them (in my project, the lines were very important in the simulation model), but of course, that depends on the frequency (the higher the frequency, the more careful you have to be)
great !
"take intou account copper lines" ==> you mean that circuit lines can have microstrip filter effects that can attenuate the power ?
thnaks :)
The lines influence the impedance seen at the input of the voltage multiplier in a significant manner (even though they are both physically and electrically small).
I wanted that impedance to be as close to reality as possible, so that I would be able to design a good matching network (so basically I have included in simulation everything I could )