The devil's in the diodes

摘要

Semiconductor diodes act like valves, converting alternating current into direct current. To work with the novel antennas, they have to operate at the AC frequencies being received and match the conductive properties of the antenna. Semiconductors are ill-suited for this, as they tend to become less conductive when shrunk to the size of the antennas. Several groups have tackled this problem, creating diodes based on different concepts. One is that at tiny scales, the physical geometry of the device influences current flow: by creating asymmetry in the geometry, electrons can be funnelled to flow one way only.