File:Braun phased array antenna 1905.png

English: First experimental phased array antenna, invented by Karl Ferdinand Braun in 1905 in Strasbourg, Germany. This was a 3 element array antenna which transmitted a beam of radio waves whose direction could be rotated electronically to 3 directions 120° apart. It consists of 3 monopole antennas at the corners of an equilateral triangle whose bisector is a quarter wavelength long. Two of the antennas are fed in phase but a quarter wave phase delay can be switched into the feed line of one. Braun won the Nobel Prize in Physics in 1909 for his radio work. Phased arrays are now widely used in radar and many other applications.