Editing Rectenna (section)

==Power beaming applications==

The invention of the rectenna in the 1960s made long distance [[wireless power|wireless power transmission]] feasible.  The rectenna was invented in 1964 and patented in 1969<ref>{{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</ref> by US electrical engineer [[William C. Brown]], who demonstrated it with a model helicopter powered by microwaves transmitted from the ground, received by an attached rectenna.<ref name="Brown">{{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}}</ref> Since the 1970s, one of the major motivations for rectenna research has been to develop a receiving antenna for proposed [[solar power satellite]]s, which would harvest energy from sunlight in space with [[solar cell]]s and beam it down to Earth as microwaves to huge rectenna arrays.<ref name="Torrey">{{cite journal |author-last=Torrey |author-first=Lee |title=A trap to harness the sun |journal=[[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}}</ref> A proposed military application is to power [[drone aircraft|drone]] [[reconnaissance aircraft]] with microwaves beamed from the ground, allowing them to stay aloft for long periods.

[[File:Millimeter wave textile rectenna.jpg|thumb| A wearable millimeter-wave textile rectenna fabricated on a textile substrate for harvesting power in the 5G K-bands (20–26.5&nbsp;GHz)]]
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]] tags, [[proximity card]]s and [[contactless smart card]]s, which contain an integrated circuit ([[integrated circuit|IC]]) 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.