The horribly named "rectenna" is a real device that turns RF into always on DC. - Page 1
Forum section: electronics / general

author: cdev
author_rank: Super Contributor
timestamp: January 02, 2019, 05:49:41 pm
content: The soon to be reality 5G network is likely to include a huge increase in cellular hardware and signal density, providing opportunities for a particular kind of 'rectifying antenna' to be used to power devices. Also charge batteries - which are proposed to be able to last 15 years or more like this.It seems that in order to make it possible to have enough powerful individually directed wireless channels, the buildout density is going to be a base station every roughly 100 to 200 meters. 5G base stations every 100-200 meters(source Texas Wireless Summit: AT&T outlines 5G network architecturehttps://www.rcrwireless.com/20161020/network-infrastructure/att-outlines-5g-network-architecture-tag4)Reading up on this I found a number of papers laying out the fact that we're going to soon have a source of both always on (very low) power (via something called a rectenna, basically a structure that extracts enough DC to power common devices out of RF) and its expected that power will also provide low power devices with network availability, not just for consumers, also for administration, virtually everywhere.I mean very low power, more than whats possible today but still very low.. (what would likely be seen as standby power with networking)MIT: 'Converting wi-fi signals into electricity':http://news.mit.edu/2019/converting-wi-fi-signals-electricity-0128Scientific American:https://www.scientificamerican.com/article/what-if-your-fitbit-could-run-on-a-wi-fi-signal/Nature: Published: 28 January 2019Two-dimensional MoS2-enabled flexible rectenna for Wi-Fi-band wireless energy harvestingAbstract:The mechanical and electronic properties of two-dimensional materials make them promising for use in flexible electronics1,2,3. Their atomic thickness and large-scale synthesis capability could enable the development of ‘smart skin’1,3,4,5, which could transform ordinary objects into an intelligent distributed sensor network6. However, although many important components of such a distributed electronic system have already been demonstrated (for example, transistors, sensors and memory devices based on two-dimensional materials1,2,4,7), an efficient, flexible and always-on energy-harvesting solution, which is indispensable for self-powered systems, is still missing. Electromagnetic radiation from Wi-Fi systems operating at 2.4 and 5.9 gigahertz8 is becoming increasingly ubiquitous and would be ideal to harvest for powering future distributed electronics. However, the high frequencies used for Wi-Fi communications have remained elusive to radiofrequency harvesters (that is, rectennas) made of flexible semiconductors owing to their limited transport properties9,10,11,12. Here we demonstrate an atomically thin and flexible rectenna based on a MoS2 semiconducting–metallic-phase heterojunction with a cutoff frequency of 10 gigahertz, which represents an improvement in speed of roughly one order of magnitude compared with current state-of-the-art flexible rectifiers9,10,11,12. This flexible MoS2-based rectifier operates up to the X-band8 (8 to 12 gigahertz) and covers most of the unlicensed industrial, scientific and medical radio band, including the Wi-Fi channels. By integrating the ultrafast MoS2 rectifier with a flexible Wi-Fi-band antenna, we fabricate a fully flexible and integrated rectenna that achieves wireless energy harvesting of electromagnetic radiation in the Wi-Fi band with zero external bias (battery-free). Moreover, our MoS2 rectifier acts as a flexible mixer, realizing frequency conversion beyond 10 gigahertz. This work provides a universal energy-harvesting building block that can be integrated with various flexible electronic systems.Thoughts:Because its ipv6 that means - individual static, hardware locked ipv6 addresses - which wont require activation or configuration.All sorts of applications which are impossibly costly to be practical today will become possible.

author: SiliconWizard
author_rank: Super Contributor
timestamp: January 02, 2019, 06:01:07 pm
content: Quote from: cdev on January 02, 2019, 05:49:41 pmI can't wait for us to be invaded by 5G base stations. Resistance will be futile!

author: WhatRoughBeast
author_rank: Newbie
timestamp: January 04, 2019, 01:05:53 am
content: If each base station serves 10,000 square yards (a 100 x 100 yard square), that will be about 300 stations per square mile.Most states have counties with population densities over 1000/square mile, but only large cities have densities over 10,000 per square mile.At 1000/square mile, you need about 1 station per every 3 people. Even in fairly dense areas, it's on the order of 1 station per every 30 people, and the thing about transmitting power is that you need to do it ALL THE TIME.So, I suggest that such a service would only be economically feasible over very small areas, which means that the service will not be reliable for anyone who moves around.In other words, I don't see your vision coming true any time soon.

author: cdev
author_rank: Super Contributor
timestamp: January 04, 2019, 02:17:26 am
content: 5G is going to be accomplished with beamforming and likely also mesh networking and fiber. The technology is very sophisticated, using high power to get over the interference, which there may be a lot of, especially since people will likely be using their internet in their cars in a way they don't today not only because they will have self driving cars that need to constantly be communicating with the other self driving cars so they dont crash, also because they wont have to concentrate on driving, so they can do work, watch a movie or whatever. All those will demand bandwidth. Visualize hundreds or even thousands of data streams all traversing the same physical space at the same time in this small area, and then repeating the same thing a few hundred yards further up the street without too many collisions strong enough to impact performance. Users devices may also forward other traffic while people are using them. Kind of like Bit Torrent.

author: soldar
author_rank: Super Contributor
timestamp: January 04, 2019, 09:45:43 am
content: "Rectenna" sounds like some instrument a doctor would use for a prostate examination."Introducing the rectenna"totally sounds like the first step in the procedure.I suggest they should find a different name.

author: bd139
author_rank: Super Contributor
timestamp: January 04, 2019, 10:01:13 am
content: Yes that's the only reason I opened this thread. Does the rectenna go up your butt?

author: Lord of nothing
author_rank: Super Contributor
timestamp: January 04, 2019, 11:36:01 am
content: Quote from: WhatRoughBeast on January 04, 2019, 01:05:53 amdepend how big your Yard is. Some People have a small and some have a bigger one.

author: cdev
author_rank: Super Contributor
timestamp: January 04, 2019, 02:46:51 pm
content: I agree it is a really really stupid name. But its been around for a while, and clearly it is supposed to describe its function of turning RF-AC into DC.Usually *quite* modest amounts of power (but evidently in the 30s enough to power a model helicopter)You can find out a lot of stuff on it using that name. If you don't use it you'll likely find little of interest. Just the usual 'energy harvesting' borderline nut cases.They also have optical 'rectennas' now that are still quite inefficient but which are a new form of PV cell, basically. And they have potential to improve quite a bit.As the amount of power available is very low (microwatts now, milliwatts eventually) but with that caveat, will be found in abundance almost everywhere where there are 5G radio transmitters, which will be almost everywhere because it will be a mesh network, with individual devices having a peer to peer function to extend the network.This is all still in the design phase, as far as I can tell.This long term low power use - where the incident RF is tapped to power sensors, and networking, (otherwise what would be the point of having sensors if they could not communicate) seems to be one of the use cases that designers are planning for. A 15 year design life seems reasonable for a machine to machine only sensor in a consumer device.Read the literature. the 5G system will operate from 600 MHz to 71 GHz, and the bandwidth occupied by individual transmissions will be very high. Also the number of different 'users' (networked devices) in a given area could be up to 1,000,000 devices per km2. (See R. E. Hattachi and J. Erfanian, "A Deliverable by the NGMN Alliance NGMN 5G white paper," Feb 17, 2015)The security of the system will have to be very high because a great deal of sensitive data will be carried by it, including health information and machine to machine communications. Its latency will also be very low. This will require as I said, a significant amount of power as well as active beam forming.If the capability is there, hobbyists will be making use of it too, I'm sure. or at least the power from it.So this is a serious post.As far as the name goes, its pretty old. Its been around for quite a while. I certainly didn't make it up.

author: vtwin@cox.net
author_rank: Regular Contributor
timestamp: January 04, 2019, 04:26:04 pm
content: Rectenna?sheesh.I thought the marketing people who came up with "Analpram" (referred to as 'Anal Ram') were idiots.

author: TerraHertz
author_rank: Super Contributor
timestamp: January 07, 2019, 02:36:52 am
content: Quote from: soldar on January 04, 2019, 09:45:43 amAnyone who's had a lower abdominal MRI, can tell you this is literally true.Except they didn't actually call it that. They _try_ to maintain decorum as much as possible. Which isn't much.

author: beanflying
author_rank: Super Contributor
timestamp: January 07, 2019, 02:48:57 am
content: Because someone had to post itDates from 1997 so either they have a sense of humor or don't watch TV.

author: cdev
author_rank: Super Contributor
timestamp: January 07, 2019, 03:03:35 am
content: Whenever I attempt to see how much DC I can extract from my environment with any type of detector at all, it registers voltage, under some conditions its much more than I ever expect.If there is any standard set of conditions we could come up with to get a relative measure of incident RF, I'm game, I'll set it up to the best of my ability. I have raw meter movements, both germanium and silicon diodes, a fairly common DMM, (a UT61e)I bet i could figure out how to make LEDs glow on their own. I've seen that happen many times, an LED will light up dimly. Is that common for you folk? I wont say its common but its easy to make that happen with only a minimal amount of planning and thought. (any tuned circuit of any size here tuned to the AM band will likely generate far more than enough)

author: amyk
author_rank: Super Contributor
timestamp: January 07, 2019, 04:00:06 am
content: Quote from: cdev on January 07, 2019, 03:03:35 amhttps://www.eevblog.com/forum/beginners/led-powered-by-soldering-iron/https://www.eevblog.com/forum/beginners/soldering-iron-is-giving-off-usable-power/https://www.eevblog.com/forum/beginners/soldering-question/https://electronics.stackexchange.com/questions/87233/why-does-an-led-light-up-when-i-touch-it

author: Red Squirrel
author_rank: Super Contributor
timestamp: January 07, 2019, 04:06:40 am
content: Was messing around with a high voltage transformer I wound myself, basically was just feeding PWM into it with a mosfet at 5v. I got a LED to light up quite easily, even a CFL tube.I also got myself to light up when I accidentally touched the end of the wire.

author: beanflying
author_rank: Super Contributor
timestamp: January 07, 2019, 04:15:17 am
content: Capacitive coupling causing LED's to glow is fairly common. I had an issue with a DC powered LED tester I built causing this across a switch until I tweaked it. Some of the house LED's give off a glow too.Pulling power out of the sky with antennas is all a bit Tesla meets free energy and reads like uBeam had a hand in it

author: tggzzz
author_rank: Super Contributor
timestamp: January 07, 2019, 09:29:42 am
content: Quote from: cdev on January 02, 2019, 05:49:41 pmActually it will be incredibly high power.Hint: if you want to be taken seriously, supply numbers or equations, not adjectives applied to unquantified amounts.

author: Zero999
author_rank: Super Contributor
timestamp: January 07, 2019, 12:33:10 pm
content: Quote from: bd139 on January 04, 2019, 10:01:13 amI wonder how many people were disappointed when they opened the thread and read it?