van Atta array

{{Short description|Passive retrodirective phased array antenna}}

A Van Atta array is a type of passive retrodirective phased array antenna which redirects (rather than reflects) a signal back in the direction from which it came. It was first described by L. C. van Atta in his 1959 patent.{{cite patent|country=US|number=2908002|title=Electromagnetic Reflector|status=patent|pubdate=1959-16-10|fdate=|pridate=|invent1=Lester C. van Atta|assign1=}}

The signal can be modulated by the redirecting host for purposes such as radio-frequency identification and traffic control (radar target echo enhancement).{{cite book |title=RF Technologies for Low-Power Wireless Communications |publisher=John Wiley & Sons |year=2001 |isbn=978-0-471-38267-6 |editor-last=Itoh |editor-first=Tatsuo |pages=341–342 |display-editors=etal}}

A 2023 paper describes the extension of the van Atta antenna principle to underwater acoustic communication.{{Cite book |last1=Eid |first1=Aline |last2=Rademacher |first2=Jack |last3=Akbar |first3=Waleed |last4=Wang |first4=Purui |last5=Allam |first5=Ahmed |last6=Adib |first6=Fadel |chapter=Enabling Long-Range Underwater Backscatter via van Atta Acoustic Networks |date=2023-09-10 |title=Proceedings of the ACM SIGCOMM 2023 Conference |language=en |publisher=ACM |pages=1–19 |doi=10.1145/3603269.3604814 |isbn=979-8-4007-0236-5|doi-access=free }}