Greenleaf Whittier Pickard (February 14, 1877 – January 8, 1956) was an American electrical engineer and inventor.

Pickard also experimented with antennas, radio wave propagation and noise suppression.

On August 30, 1906 he filed a patent for a silicon crystal detector, which was granted on November 20, 1906.

Pickard's loop antenna had directional properties that could be used to reduce interference to the intended wireless communications.

On June 21, 1911 he filed a patent on a crystal detector incorporating a springy low inertia wire of about 24 gauge formed with a loop or helix and pointed to make contact with the crystal.