Need ideas for a broadband RF energy harvesting module demonstration... - Page 1
Forum section: electronics / rf-microwave

author: energy_hunter
author_rank: Contributor
timestamp: February 21, 2016, 08:40:18 pm
content: I am trying to sell a very broadband RF-DC converter called the RFD102A atwww.rfdiagnostics.com. It works optimally from 10MHz...6GHz and converts RF signals to DC when connected to an antenna. I have made the following demos with the part but need more interesting ideas for demo projects with low current.http://www.instructables.com/id/Microwave-Oven-Energy-HarvestingDetector/http://www.instructables.com/id/RFD102A-Holiday-Microwave-Oven-Lights/The module was designed to be very sensitive to low powers (-14dBm) but because of this choice/tradeoff it only puts out <18mA.Please help me brainstorm! Gracias.

author: JimRemington
author_rank: Regular Contributor
timestamp: February 24, 2016, 06:13:59 pm
content: Those parts look interesting, but the data sheet is more of a user guide and has very little information.It would be nice to know about the input impedance (R/I) and conversion efficiency versus input voltage and frequency, etc. Is that information available somewhere?

author: Gribo
author_rank: Frequent Contributor
timestamp: February 25, 2016, 07:36:42 pm
content: -14dBm is not low.. Anyway, there are many sensors which can benefit from such harvester. Soil humidity for pots, Local temperature, various light sensing applications and so on.

author: daqq
author_rank: Super Contributor
timestamp: February 26, 2016, 11:30:24 am
content: A very nice demonstration video (or demo setup in a expo booth) would be if you had an array of these (say, 40x40), and you had a LED connected on every one. Then people could come and play around with moving typical transmitter devices (router, cell phone...) around the array and visualize the field.

author: energy_hunter
author_rank: Contributor
timestamp: March 23, 2016, 09:53:38 pm
content: Thanks for all the suggestions.I have attached an image of an array of ~30 RFD102A-DET parts that are on a microwave oven at the seam of the door. The RF hotspot moves around as the microwave tray spins the coffee mug. It's a great idea to put the parts on a sheet of paper and move it around near a transmitter. There could be some fun experiments to do with the spacing of the parts to see what works best or maybe a sheet on the microwave oven window to pick up some of the microwave energy.Regarding the matching of the parts, I have S-parameters of the part on a test board at powers from -15dBm to +10dBm. As the part is exposed to more input power the match changes. It think it's a good idea to include S11 vs. Input Power in a table format or on a Smith Chart in the datasheet. Thanks for pointing this out. I haven't done load-pull of these parts so I don't know if certain matches improve efficiency or sensitivity.

author: energy_hunter
author_rank: Contributor
timestamp: March 23, 2016, 09:58:34 pm
content: S-parameters of the RFD102A-TB (part on a test board with the reference plane at the SMA connector) at different input powers.

author: hendorog
author_rank: Super Contributor
timestamp: March 23, 2016, 10:10:34 pm
content: Random thought - generate power by connecting the antenna input with the mains earth wire? (assuming you know how to do that safely!)Might be a cool demo....

author: hendorog
author_rank: Super Contributor
timestamp: March 23, 2016, 10:33:51 pm
content: This might be of interest:http://hackaday.com/2011/12/31/using-mains-wiring-as-an-antenna/

author: energy_hunter
author_rank: Contributor
timestamp: March 23, 2016, 11:10:47 pm
content: Thanks hendorog for the idea. Here are the results and they look very good. I took the RFD102A-TB (test board), used two banana plugs to connect to a banana to BNC to SMA adapter. The banana plug wires were 2 feet long (~61cm) and I had a dangling GND wire and I put the signal plug into the earth/GND pin on a 2nd floor AC outlet. When I was not touching anything, I measured 0.3V...0.5V into a voltmeter (>1MOHM). As soon as I touched the GND of the adapter the voltage jumped to 1.0...1.2V. I believe that I'm helping form the other arm of an antenna and am picking up signals of my own. When I disconnect the banana plug from the AC GND socket then I measure a low level of 30mV.So an improvement to your idea is to connect the signal pin to the ground/earth of the AC outlet and connect the ground of the RFD102A-TB to the metal plumbing so that you get more AC signals into the RF-DC converter.Thanks for your post!

author: hendorog
author_rank: Super Contributor
timestamp: March 23, 2016, 11:22:23 pm
content: SweetThat makes sense as you/the plumbing is acting as a counterpoise and balancing the antenna well enough to generate some power.

author: bruce2hs
author_rank: Newbie
timestamp: October 14, 2019, 05:15:51 am
content: I would like to use the RFD102a with a mylar film, using stripline inductors tuned to various free space radiation such as Communication Micro wave, Cell phone, UHF and VHF Communication and a one large one tuned to 60hz. This could be adhered to the Roof, hood and/or trunk of an electric automobile and used for passive RF inductive battery charge. The 60Hz would have to be able to be cut out as to not bleed off too much power from a singe location. Several converter modules may be needed to handle the wide frequency bands and power levels.

author: energy_hunter
author_rank: Contributor
timestamp: October 14, 2019, 01:03:35 pm
content: A log periodic antenna seems to be the best broadband choice for connecting to the RFD102A. The module can convert 60Hz energy to a DC voltage but is not optimal since the series capacitors in the design limit the lower frequency performance (say 10MHz is probably the lower limit for efficient RF-DC conversion). The RFD199A-PCB may be a better option since this module has higher current output and a regulator circuit for power management. It also have a 5.6V Zener to limit the output voltage.