IMS2012 International Microwave Symposium

Man's first awareness of electromagnetic phenomena probably started with the very dawn of civilization. About 600 BC Thales of Miletus, a Greek philosopher, noted that a piece of amber could be made to attract small particles by rubbing it with cloth. Aristotle, in 400 BC, maintained that a force could not be communicated between bodies other than by some tangible means as pressure or impact. Lucretius of Magnesia (98-55 BC) noted the power of lodestone to attract iron.

                   

More recently, William Gilbert (1544-1603), physician to Queen Elizabeth I, expressed the opinion that electrical phenomena are due to something material which is liberated from bodies when electrified by friction, without any change in form or weight.

René Descartes (1596-1650) believed that magnetism consisted of vortexes in an omnipresent aether. The idea was later expressed by Leonhard Euler (1707-1783) and James Clark Maxwell in 1861.

                   

Karl Friedrick Gauss (1777-1855), German mathematician, made one of the first attempts to deduce the fundamental law of electromagnetic action in terms of an electric field propagated at finite velocity.

The first recorded statement on the subject of electro-magnetism was made by Michael Faraday in 1846, suggesting the propagation of magnetic disturbances by means of transverse vibrations. Faraday's greatest discovery was that of electromagnetic induction.

James Clerk Maxwell (1831-1879) translated Faraday's experiments in electromagnetism into mathematical notations. Maxwell expressed all the fundamental laws of light, electricity and magnetism in "Maxwell Field Equations." These equations, along with Newton's Laws, the Quantum Theory and the Theory of Relativity, are considered the mathematical foundation of the physical universe.

Through a series of brilliant experiments, Heinrich Hertz (1857-1894) established beyond doubt the electromagnetic nature of light and thereby confirmed Maxwell's Theory.

Guglielmo Marconi (1874-1937) first recognized the possibility of using electromagnetic waves as a means of wireless communication. He built parabolic antennas and moved to higher and higher frequencies eventually reaching 550 MHz.

Credit for the first waveguide experiments probably belongs to George C. Southworth. In 1920, he measured the wavelength of a high frequency signal on a lecher wire frame in air, and then in a trough of water. After observing evidence of other wavelength components superimposed on those expected in water, Dr. Southworth decided that they were related to the dimensions of the trough. While working for AT&T in 1933, he was able to transmit and receive telegraph signals using 20 feet of 4 and 5 inch diameter pipes.

The beginnings of radar were influenced by Albert H. Taylor and Leo C. Young in 1922 when they noticed an unexpected swell in what had been a steady tone of communication, which then faded coinciding with an object crossing the line of sight between the transmitter and receiver. This phenomenon was related to the need for detection of enemy ships.

         

Little development of radar occurred until 1934, when the United States Naval Research Laboratory, the Germans, and the British began work on it. The klystron was invented at Stanford University in 1937 by Russell Varian along with Sigurd Varian and W. W. Hansen, with funding by Sperry Gyroscope Company looking for solutions to an instrument landing problem.

                   

During World War II, Radar became the major application of microwave technology. By 1940, the British had installed a chain of radar installations along the coastline to warn against air attack.

Just prior to World War II, Harry Boot and John Randall invented the 10 cm pulsed-cavity magnetron in England using Hertz's original experiments with loops and gaps as a basis for arranging a number of cylindrical resonators in a circle.

         

In mid-1940, British personnel led by Sir Henry Tizard brought the device to the U.S. and Canada, initiating the success of Microwave Radar during World War II.

Work was then begun on development of U.S. radar systems, primarily by MIT Radiation Laboratory, but also at other defense industry companies. Many of the subcontracting decisions made then led to the companies' areas of specialization in today's microwave industry.

After World War II, funding for further development in the microwave field was reduced drastically, and research and development efforts over the next 40 years were tied to fluctuations in the U.S. defense budget, with the search for commercial applications occurring generally during low periods in the government demand. Applications developed included communications, commercial radar, industrial heating, and industrial measurements.

Courtesy National Electronics Museum