# Rectenna > Mediated Wiki article. Canonical URL: https://mediated.wiki/source/Rectenna > Markdown URL: https://mediated.wiki/source/Rectenna.md > Source: https://en.wikipedia.org/wiki/Rectenna > Source revision: 1339907146 > License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) {{Short description|Antenna for receiving power}} {{Use dmy dates|date=May 2022|cs1-dates=y}} {{Anchor|Filtenna}} thumb|right|alt=A printed rectenna lighting an LED from a Powercast 915 MHz transmitter, flexible meshed antenna bent with a red LED light|A printed meshed rectenna lighting an LED from a Powercast 915 MHz transmitter A '''rectenna''' ('''''rect''ifying ant''enna''''') is a special type of receiving [antenna](/source/antenna_(electronics)) that is used for converting [electromagnetic](/source/electromagnetic) energy into [direct current](/source/direct_current) (DC) [electricity](/source/electricity). They are used in [wireless power transmission](/source/wireless_power_transmission) systems that transmit power by [radio waves](/source/radio_waves). A simple rectenna element consists of a [dipole antenna](/source/dipole_antenna) with a [diode](/source/diode) connected across the dipole elements. The diode [rectifies](/source/rectifier) the [AC](/source/alternating_current) induced in the antenna by the microwaves, to produce DC power, which powers a load connected across the diode. [Schottky diode](/source/Schottky_diode)s are usually used because they have the lowest voltage drop and highest speed and therefore have the lowest power losses due to conduction and switching.{{cite book |doi=10.1109/MWSCAS.2017.8053188 |chapter=A dual-mode passive rectifier for wide-range input power flow |title=2017 IEEE 60th International Midwest Symposium on Circuits and Systems (MWSCAS) |pages=1376–1379 |date=2017 |author-last1=Guler |author-first1=Ulkuhan |author-last2=Sendi |author-first2=Mohammad S. E. |author-last3=Ghovanloo |author-first3=Maysam |isbn=978-1-5090-6389-5 |s2cid=31003912}} Large rectennas consist of arrays of many power receiving elements such as dipole antennas. ==Power beaming applications== thumb| A wearable millimeter-wave textile rectenna fabricated on a textile substrate for harvesting power in the 5G K-bands (20–26.5 GHz) The invention of the rectenna in the 1960s made long distance [wireless power transmission](/source/wireless_power) feasible. The rectenna was invented in 1964 and patented in 1969{{patent|US|3434678}} ''[https://patents.google.com/patent/US3434678 Microwave to DC Converter]'' William C. Brown, ''et al'', filed 5 May 1965, granted 25 March 1969 by US electrical engineer [William C. Brown](/source/William_C._Brown), who demonstrated it with a model helicopter powered by microwaves transmitted from the ground, received by an attached rectenna.{{cite web |title=William C. Brown |work=Project #07-1726: Cutting the Cord |publisher=2007–2008 Internet Science & Technology Fair, Mainland High School |date=2012 |url=http://mainland.cctt.org/istf2008/brown.asp |access-date=2012-03-30}} Since the 1970s, one of the major motivations for rectenna research has been to develop a receiving antenna for proposed [solar power satellite](/source/solar_power_satellite)s, which would harvest energy from sunlight in space with [solar cell](/source/solar_cell)s and beam it down to Earth as microwaves to huge rectenna arrays.{{cite journal |author-last=Torrey |author-first=Lee |title=A trap to harness the sun |journal=[New Scientist](/source/New_Scientist) |volume=87 |issue=1209 |pages=124–127 |date=1980-07-10 |url=https://books.google.com/books?id=vfQxekunC3QC&q=rectenna&pg=PA125 |issn=0262-4079 |access-date=2012-03-30}} A proposed military application is to power [drone](/source/drone_aircraft) [reconnaissance aircraft](/source/reconnaissance_aircraft) with microwaves beamed from the ground, allowing them to stay aloft for long periods. In recent years, interest has turned to using rectennas as power sources for small wireless microelectronic devices. The largest current use of rectennas is in [RFID](/source/RFID) tags, [proximity card](/source/proximity_card)s and [contactless smart card](/source/contactless_smart_card)s, which contain an integrated circuit ([IC](/source/integrated_circuit)) which is powered by a small rectenna element. When the device is brought near an electronic reader unit, radio waves from the reader are received by the rectenna, powering up the IC, which transmits its data back to the reader. ==Radio frequency rectennas== The simplest [crystal radio](/source/crystal_radio) receiver, employing an [antenna](/source/antenna_(radio)) and a [demodulating](/source/demodulation) [diode](/source/diode) ([rectifier](/source/rectifier)), is actually a rectenna, although it discards the [DC component](/source/DC_bias) before sending the signal to the [headphones](/source/headphones). People living near strong radio [transmitter](/source/transmitter)s would occasionally discover that with a long receiving antenna, they could get enough electric power to light a light bulb.{{cite web |url=http://web.physics.ucsb.edu/~lecturedemonstrations/Composer/Pages/76.09.html |title=76.09 — Radio transmitter lights antenna bulb}} However, this example uses only one antenna having a limited capture area. A rectenna array uses multiple antennas spread over a wide area to capture more energy. Researchers are experimenting with the use of rectennas to power sensors in remote areas and distributed networks of sensors, especially for [IoT](/source/Internet_of_things) applications.{{cite news |title=Over to you: Mythical electricity? |url=https://www.telegraph.co.uk/scienceandtechnology/technology/3336114/Over-to-you-Mythical-electricity.html |archive-url=https://web.archive.org/web/20090628191010/http://www.telegraph.co.uk/scienceandtechnology/technology/3336114/Over-to-you-Mythical-electricity.html |archive-date=2009-06-28 |date=2004-11-24 |access-date=2009-06-25 |publisher=[The Daily Telegraph](/source/The_Daily_Telegraph)}} RF rectennas are used for several forms of [wireless power transfer](/source/wireless_power_transfer). In the microwave range, experimental devices have reached a power conversion efficiency of 85–90%.{{cite thesis |type=PhD Thesis |author-last=Zhang |author-first=J. |date=2000 |title=Rectennas for RF wireless energy harvesting |publisher=University of Liverpool |url=https://livrepository.liverpool.ac.uk/18537/}} The record conversion efficiency for a rectenna is 90.6% for 2.45 GHz,McSpadden, J. O., Fan, L., and Kai Chang, "Design and Experiments of a High-Conversion-Efficiency 5.8-GHz Rectenna," ''IEEE Trans. Microwave Theory and Technique'', Vol. 46, No. 12, December 1998, pp. 2053–2060. https://ieeexplore.ieee.org/document/739282 with lower efficiency of about 82% achieved at 5.82 GHz. ==Optical rectennas== {{Main|Optical rectenna}} In principle, similar devices, scaled down to the proportions used in [nanotechnology](/source/nanotechnology), can be used to convert [light](/source/light) directly into electricity. This type of device is called an ''[optical rectenna](/source/optical_rectenna)'' (or "nantenna").{{cite journal |author-first1=Asha |author-last1=Sharma |author-first2=Virendra |author-last2=Singh |author-first3=Thomas L. |author-last3=Bougher |author-first4=Baratunde A. |author-last4=Cola |date=2015-10-09 |url=https://zenodo.org/record/851685 |journal=Nature Nanotechnology |volume=10 |issue=12 |pages=1027–1032 |title=A carbon nanotube optical rectenna |doi=10.1038/nnano.2015.220 |pmid=26414198 |bibcode=2015NatNa..10.1027S}}{{cite press release |date=2015-09-28 |title=First optical rectenna -- combined rectifier and antenna -- converts light to DC current |website=EurekAlert! |url=http://www.eurekalert.org/pub_releases/2015-09/giot-for092315.php |access-date=2015-10-01 |archive-date=2019-02-01 |archive-url=https://web.archive.org/web/20190201065554/https://www.eurekalert.org/pub_releases/2015-09/giot-for092315.php }}Patent application {{patent|WO|2014063149}} relates. Theoretically, high efficiencies can be maintained as the device shrinks, but to date efficiency has been limited, and so far there has not been convincing evidence that rectification has been achieved at optical frequencies. The [University of Missouri](/source/University_of_Missouri) previously reported on work to develop low-cost, high-efficiency optical-frequency rectennas.{{cite press release |url=http://munews.missouri.edu/news-releases/2011/0516-new-solar-technology-could-break-photovoltaic-limits/ |title=New solar technology could break photovoltaic limits |publisher=[University of Missouri](/source/University_of_Missouri) |date=2011-05-16}} Other prototype devices were investigated in a collaboration between the [University of Connecticut](/source/University_of_Connecticut) and [Penn State Altoona](/source/Penn_State_Altoona) using a grant from the [National Science Foundation](/source/National_Science_Foundation).{{cite press release |url=http://today.uconn.edu/blog/2013/02/uconn-professors-patented-technique-key-to-new-solar-power-technology/ |title=UConn Professor's Patented Technique Key to New Solar Power Technology |date=2013-02-04 |author-first=Colin |author-last=Poitras}} With the use of [atomic layer deposition](/source/atomic_layer_deposition) it has been suggested that conversion efficiencies of solar energy to electricity higher than 70% could eventually be achieved. The creation of successful optical rectenna technology has two major complicating factors: # Fabricating an antenna small enough to couple optical wavelengths. # Creating an ultra-fast diode capable of rectifying the high frequency oscillations, at frequency of c. 500 THz. Below are a few examples of potential paths to creating diodes that would be fast enough to rectify optical and near-optical radiation. A promising path towards creating these ultrafast diodes has been in the form of "[geometric diode](/source/geometric_diode)s".{{Cite book |author-last=Zhu |author-first=Z. |title=Rectenna Solar Cells |publisher=Springer |date=2013 |location=New York |pages=209–227}} Graphene geometric diodes have been reported to rectify [terahertz radiation](/source/terahertz_radiation).{{Cite journal |author-last1=Zhu |author-first1=Zixu |author-last2=Joshi |author-first2=Saumil |author-last3=Grover |author-first3=Sachit |author-last4=Moddel |author-first4=Garret |date=2013-04-15 |title=Graphene geometric diodes for terahertz rectennas |journal=Journal of Physics D: Applied Physics |volume=46 |issue=18 |article-number=185101 |doi=10.1088/0022-3727/46/18/185101 |bibcode=2013JPhD...46r5101Z |s2cid=9573157 |issn=0022-3727}} In April 2020, geometric diodes were reported in [silicon](/source/silicon) [nanowire](/source/nanowire)s.{{Cite journal |author-last1=Custer |author-first1=James P. |author-last2=Low |author-first2=Jeremy D. |author-last3=Hill |author-first3=David J. |author-last4=Teitsworth |author-first4=Taylor S. |author-last5=Christesen |author-first5=Joseph D. |author-last6=McKinney |author-first6=Collin J. |author-last7=McBride |author-first7=James R. |author-last8=Brooke |author-first8=Martin A. |author-last9=Warren |author-first9=Scott C. |author-last10=Cahoon |author-first10=James F. |date=2020-04-10 |title=Ratcheting quasi-ballistic electrons in silicon geometric diodes at room temperature |url=https://www.science.org/doi/10.1126/science.aay8663 |journal=Science |language=en |volume=368 |issue=6487 |pages=177–180 |doi=10.1126/science.aay8663 |issn=0036-8075 |pmid=32273466 |bibcode=2020Sci...368..177C |s2cid=215550903|url-access=subscription }} The wires were shown experimentally to rectify up to 40 GHz, that result was the limit of the instrument used, and the wires theoretically may be able to rectify signals in the terahertz region as well. == See also == * [Microstrip antenna](/source/Microstrip_antenna) * [Wireless power transfer](/source/Wireless_power_transfer) ==References== {{Reflist}} ==External links== {{Commonscat}} * [https://web.archive.org/web/20090802101748/http://www.mtt.org/awards/WCB%27s%20distinguished%20career.htm William C. Brown's Distinguished Career] * {{Cite journal |doi=10.1038/s41586-019-0892-1 |pmid=30692651 |title=Two-dimensional MoS2-enabled flexible rectenna for Wi-Fi-band wireless energy harvesting |journal=Nature |date=2019 |author-last1=Zhang |author-first1=Xu |author-last2=Grajal |author-first2=Jesús |author-last3=Vazquez-Roy |author-first3=Jose Luis |author-last4=Radhakrishna |author-first4=Ujwal |author-last5=Wang |author-first5=Xiaoxue |author-last6=Chern |author-first6=Winston |author-last7=Zhou |author-first7=Lin |author-last8=Lin |author-first8=Yuxuan |author-last9=Shen |author-first9=Pin-Chun |author-last10=Ji |author-first10=Xiang |author-last11=Ling |author-first11=Xi |author-last12=Zubair |author-first12=Ahmad |author-last13=Zhang |author-first13=Yuhao |author-last14=Wang |author-first14=Han |author-last15=Dubey |author-first15=Madan |author-last16=Kong |author-first16=Jing |author-last17=Dresselhaus |author-first17=Mildred |author-link17=Mildred Dresselhaus |author-last18=Palacios |author-first18=Tomás |volume=566 |issue=7744 |pages=368–372 |bibcode=2019Natur.566..368Z |s2cid=59307657|url=https://oa.upm.es/79152/ }} ** {{Cite press release |date=2019-01-28 |title=Converting Wi-Fi signals to electricity with new 2D materials |website=ScienceDaily |url=https://www.sciencedaily.com/releases/2019/01/190128111718.htm}} {{Antenna Types}} Category:Antennas Category:Radio frequency antenna types Category:Solar cells --- Adapted from the Wikipedia article [Rectenna](https://en.wikipedia.org/wiki/Rectenna) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Rectenna?action=history)). 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