English: Microwave transmitter and receiver used by Sir Jagadish Chandra Bose (also written Jagadis Chunder Bose) (30 November, 1858 – 23 November, 1937), in his pioneering experiments with microwaves around 1897. The spark gap transmitter (right) used a spark gap radiator made of three tiny 3 mm metal balls excited by high voltage from an induction coil to generate microwaves at 60 GHz. The transmitter was enclosed inside the metal box (right) to prevent sparks from the coil's interrupter from disturbing the action of the receiver, and the microwaves emanated from the waveguide (metal tube). The receiver (left) used a galena point contact crystal rectifier inside the horn antenna and a galvanometer to detect the waves. The galvanometer (left) and battery (right) are modern replacements for Bose's original apparatus.
Bose was the first to invent the crystal detector, horn antenna, dielectric lens, and other components now used in microwave apparatus. Jagadish Chandra Bose museum which is the part of the Bose Institute, Kolkata, is displaying some of the instruments designed, made and used by Sir J. C. Bose with his personal belongings, memorabilia and an exhibition on his Life and Works.