Solid State Rectifier

Semiconductor technology took a giant leap forward during World War II, as radar receivers needed solid-state rectifiers to detect and convert microwave signals at frequencies higher than possible using vacuum tube diodes. Silicon and germanium emerged as the dominant semiconductor materials due to wartime R&D efforts. Millions of crystal rectifier diodes, with a metal point contacting a tiny sliver of silicon or germanium inside, were fabricated for use in Allied radar receivers.
So generally rectifier is an electrical device that converts alternating current (AC), which periodically reverses direction, to direct current (DC), which flows in only one direction. The process is known as rectification. Physically, rectifiers take a number of forms, including vacuum tube diodes, mercury-arc valves, copper and selenium oxide rectifiers, solid-state diodes, silicon-controlled rectifiers and other silicon-based semiconductor switches. Early radio receivers, called crystal radios, used a "cat's whisker" of fine wire pressing on a crystal of galena (lead sulphide) to serve as a point-contact rectifier or "crystal detector".

Cat's Whisker Detector

The cat's whisker detector is one of the most iconic components used in early radio sets. Also called the crystal detector it was an iconic component used in many early radio equipments.Today, many cat's whisker or crystal detectors sets can be seen on the antique and collectors market.In their day, the radios using the cats' whisker detector or the crystal detector performed well and for many years they were the main type of detector used in sets used for the reception of broadcast transmissions. The "cat's whisker", a springy piece of thin metal wire, formed the metal side of the junction. Phosphor bronze wire of about 30 gauges was commonly used because it had the optimal amount of