Walter Rotman (August 24, 1922 – May 19, 2007) was an American scientist known for his work in

radar Radar is a detection system that uses radio waves to determine the distance (''ranging''), angle, and radial velocity of objects relative to the site. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, w ...

and

antenna Antenna ( antennas or antennae) may refer to: Science and engineering * Antenna (radio), also known as an aerial, a transducer designed to transmit or receive electromagnetic (e.g., TV or radio) waves * Antennae Galaxies, the name of two collid ...

design. Among his inventions were the Rotman lens, the sandwich wire antenna, and the trough

waveguide A waveguide is a structure that guides waves, such as electromagnetic waves or sound, with minimal loss of energy by restricting the transmission of energy to one direction. Without the physical constraint of a waveguide, wave intensities de ...

Biography

Walter Rotman was born on August 24, 1922, in St. Louis, Missouri. He served in the United States Air Force during

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...

as a technician for the radar division. After the war, he studied electrical engineering at

MIT The Massachusetts Institute of Technology (MIT) is a private land-grant research university in Cambridge, Massachusetts. Established in 1861, MIT has played a key role in the development of modern technology and science, and is one of the mo ...

where he received his

BSc A Bachelor of Science (BS, BSc, SB, or ScB; from the Latin ') is a bachelor's degree awarded for programs that generally last three to five years. The first university to admit a student to the degree of Bachelor of Science was the University of ...

and

MSc MSC may refer to: Computers * Message Sequence Chart * Microelectronics Support Centre of UK Rutherford Appleton Laboratory * MIDI Show Control * MSC Malaysia (formerly known as Multimedia Super Corridor) * USB mass storage device class (USB MSC ...

. In 1948, he joined the research laboratories of the Air Force (

AFRL The Air Force Research Laboratory (AFRL) is a scientific research organization operated by the United States Air Force Materiel Command dedicated to leading the discovery, development, and integration of aerospace warfighting technologies, pl ...

) where he became the branch chief of a laboratory concentrating on investigating the effect of plasma on re-entry vehicles. In 1980, he retired from

and joined

MIT Lincoln Laboratory The MIT Lincoln Laboratory, located in Lexington, Massachusetts, is a United States Department of Defense federally funded research and development center chartered to apply advanced technology to problems of national security. Research and dev ...

where he worked on reflector antennas until his retirement in 1990. He died on May 19, 2007, at the age of 84 in Boston, Massachusetts.

Scientific advancements

Rotman lens

Rotman is best known for the lens named after him, the Rotman lens. The lens allows radar systems to simultaneously see targets in multiple directions (multi-beam capability) without physically moving the antenna system. This lens is now integrated into many radars and EW systems around the world.

Surface wave antennas

Rotman invented many types of surface wave antennas including the trough waveguide, the channel waveguide, and the sandwich wire antenna. These periodic structures which he analyzed together with Arthur Oliner allow antennas to scan in various directions by changing frequencies. The sandwich wire antenna was one of the first attempts to use the then-new techniques of

microstrip Microstrip is a type of electrical transmission line which can be fabricated with any technology where a conductor is separated from a ground plane by a dielectric layer known as the substrate. Microstrip lines are used to convey microwave-frequ ...

and

stripline Stripline is a transverse electromagnetic (TEM) transmission line medium invented by Robert M. Barrett of the Air Force Cambridge Research Centre in the 1950s. Stripline is the earliest form of planar transmission line. Description A strip ...

to create an antenna.

Metamaterials

Building upon previous work, Rotman used a grid of three-dimensional thin wires to simulate plasmas with

dielectric constant The relative permittivity (in older texts, dielectric constant) is the permittivity of a material expressed as a ratio with the electric permittivity of a vacuum. A dielectric is an insulating material, and the dielectric constant of an insulat ...

s less than one. It is considered today as a classic paper as it showed the potential of

artificial dielectrics Artificial dielectrics are fabricated composite materials, often consisting of arrays of conductive shapes or particles in a nonconductive support matrix, designed to have specific electromagnetic properties similar to dielectrics. As long as the l ...

. In this paper, Rotman reached equations in a relatively simple manner which were derived again twenty years later.J.B.Pendry, A.J. Holden and D.J. Robinns, "Low Frequency Plasmons in Thin-Wire Structures," Journal of Physics: Condensed Matter 10(22) 4785-809, 1998 However, Rotman did not attempt to use these grids to simulate negative epsilon material, possibly because he saw the difficulties with dispersion and loss which would occur.

Published works and achievements

Rotman wrote several classic works and papers on the interference of radar plasma on re-entry vehicles and on simulation of plasmas via a grid of thin rods which was an early inspiration for today's work on

metamaterials A metamaterial (from the Ancient Greek, Greek word Meta, μετά ''meta'', meaning "beyond" or "after", and the Latin word ''materia'', meaning "matter" or "material") is any material engineered to have a property that is not found in naturally ...

. Rotman was awarded many honors. He was elected an

IEEE Fellow As of 2019, the Institute of Electrical and Electronics Engineers (IEEE) has 5,082 members designated Fellow, each of whom is associated with one of the 41 societies under the IEEE. The Fellow grade of membership is the highest level of membershi ...

in 1968 for contributions to antenna technology. He received the

IEEE Centennial Medal The IEEE Centennial Medal was a medal minted and awarded in 1984 ''to persons deserving of special recognition for extraordinary achievement'' to celebrate the Centennial of the founding of the Institute of Electrical and Electronics Engineers (I ...

in 1984 and the USAF Decoration for Exceptional Civilian Service in 1980, and in 2005 he received the John Kraus Antenna Award.

References

; Notes *

External links

Rotman Lens
from Microwaves101.com - Microwave Encyclopedia
Rotman Lens Patent
from Google Patents
Sandwich Wire Antenna Patent
from Google Patents
Trough Waveguide Patent
from Google Patents {{DEFAULTSORT:Rotman, Walter Jewish American scientists American electrical engineers 1922 births 2007 deaths Radar pioneers MIT School of Engineering alumni Scientists from St. Louis MIT Lincoln Laboratory people Fellow Members of the IEEE IEEE Centennial Medal laureates 20th-century American engineers Microwave engineers United States Army Air Forces personnel of World War II 20th-century American Jews 21st-century American Jews