1964: Rectenna - The book of science

Rectenna
Rectenna uses
Resonance
Commentary

Rectenna

William C. Brown invented
the rectifying antenna as part of his design
for wireless power transmission.
He demonstrated a model helicopter
containing a small rectenna
and powered by microwaves.

Rectenna uses

A RFID tag is powered by radio waves
gathered and rectified by its rectenna
to transmit its data to an RFID reader.
A satellite in constant sunlight may collect
solar energy and send it as microwaves
to large rectenna arrays on Earth.
An optical rectenna may convert light waves
directly into electricity, although challenges
for its design and manufacture remain.

Resonance

Nikola Tesla’s wireless power transmission
used resonant induction, which he thought
would let him transmit power to any point on Earth
if he could make Earth’s potential resonate.
Early attempts to invent radio transmission
caused confusion between electromagnetic induction (which
is used today only between nearby wire coils) and
electromagnetic radiation (which can travel long distances).
I wrack my brain for other forms of energy
that we could harvest with rectennas.
I’m wondering, “Virtual particles?”
So many are whirring about from quark to quark!

William C. Brown’s design for a rectenna featured diode bridges producing a continuous pulsed direct current. The difficulty in producing optical rectennas is that even the fastest diodes today cannot handle the high frequencies of light waves.