Charles Stuart Ballantine (September 22, 1897May 7, 1944) was an American

inventor An invention is a unique or novel device, method, composition, idea or process. An invention may be an improvement upon a machine, product, or process for increasing efficiency or lowering cost. It may also be an entirely new concept. If an id ...

. Ballantine was born in the Germantown section of

Philadelphia Philadelphia, often called Philly, is the largest city in the Commonwealth of Pennsylvania, the sixth-largest city in the U.S., the second-largest city in both the Northeast megalopolis and Mid-Atlantic regions after New York City. Sinc ...

Pennsylvania Pennsylvania (; (Pennsylvania Dutch: )), officially the Commonwealth of Pennsylvania, is a state spanning the Mid-Atlantic, Northeastern, Appalachian, and Great Lakes regions of the United States. It borders Delaware to its southeast, Ma ...

. He was an amateur radio enthusiast by 1908 and served as a ship radio operator during the summers of 1913-1915. He was employed in 1916 by H. K. Mulford Company,

biochemist Biochemists are scientists who are trained in biochemistry. They study chemical processes and chemical transformations in living organisms. Biochemists study DNA, proteins and cell parts. The word "biochemist" is a portmanteau of "biological che ...

s, and in 1917 by the

Bell Telephone Company The Bell Telephone Company, a common law joint stock company, was organized in Boston, Massachusetts, on July 9, 1877, by Alexander Graham Bell's father-in-law Gardiner Greene Hubbard, who also helped organize a sister company – the New Engl ...

of Pennsylvania. From 1917 to 1920 Ballantine attended

Drexel Institute Drexel University is a private research university with its main campus in Philadelphia, Pennsylvania. Drexel's undergraduate school was founded in 1891 by Anthony J. Drexel, a financier and philanthropist. Founded as Drexel Institute of Art, S ...

and worked as a radio expert at the

Philadelphia Naval Shipyard The Philadelphia Naval Shipyard was an important naval shipyard of the United States for almost two centuries. Philadelphia's original navy yard, begun in 1776 on Front Street and Federal Street in what is now the Pennsport section of the ci ...

, where he led design of the Navy coil-type

radio compass Direction finding (DF), or radio direction finding (RDF), isin accordance with International Telecommunication Union (ITU)defined as radio location that uses the reception of radio waves to determine the direction in which a radio stat ...

es. He discovered the "antenna effect" in such systems and invented the capacity compensator for its control. In 1920-1921 he undertook graduate studies in

mathematical physics Mathematical physics refers to the development of mathematics, mathematical methods for application to problems in physics. The ''Journal of Mathematical Physics'' defines the field as "the application of mathematics to problems in physics and t ...

Harvard University Harvard University is a private Ivy League research university in Cambridge, Massachusetts. Founded in 1636 as Harvard College and named for its first benefactor, the Puritan clergyman John Harvard, it is the oldest institution of high ...

, then spent a year at the Radio Frequency Laboratories in

Boonton, New Jersey Boonton is a town in Morris County, New Jersey, United States. As of the 2020 United States census, the town's population was 8,815, an increase of 468 (+5.6%) from the 2010 census count of 8,347, which in turn reflected a decline of 149 (� ...

, where he worked on radio receivers and made inventions for stabilization of radio-frequency amplifiers via a

Wheatstone bridge A Wheatstone bridge is an electrical circuit used to measure an unknown electrical resistance by balancing two legs of a bridge circuit, one leg of which includes the unknown component. The primary benefit of the circuit is its ability to provide ...

, linear detection at high signal levels, and

automatic volume control Automatic gain control (AGC) is a closed-loop feedback regulating circuit in an amplifier or chain of amplifiers, the purpose of which is to maintain a suitable signal amplitude at its output, despite variation of the signal amplitude at the inpu ...

. He returned to Harvard 1923-1924 as a

John Tyndall John Tyndall Fellow of the Royal Society, FRS (; 2 August 1820 – 4 December 1893) was a prominent 19th-century Irish physicist. His scientific fame arose in the 1850s from his study of diamagnetism. Later he made discoveries in the realms of ...

scholar in physics. From 1924 to 1927 Ballantine carried out independent studies of radio propagation in

White Haven, Pennsylvania White Haven is a borough in Luzerne County, Pennsylvania. It is located along the Lehigh River. The population was 1,163 at the 2020 census. History Establishment White Haven was created in 1824 by industrialist Josiah White. It was later incorpo ...

, then was briefly research director at the Radio Frequency Laboratories, and in 1929 collaborated with F. M. Huntoon in studying the effects of high pressure on bacteria. From 1929 to 1934 he was President of the Boonton Research Laboratories investigating errors in microphones due to diffraction and cavity resonance, and developing new devices including an electrostethoscope, automatic optical recorder for frequency-response measurements, and

logarithm In mathematics, the logarithm is the inverse function to exponentiation. That means the logarithm of a number to the base is the exponent to which must be raised, to produce . For example, since , the ''logarithm base'' 10 of ...

voltmeter A voltmeter is an instrument used for measuring electric potential difference between two points in an electric circuit. It is connected in parallel. It usually has a high resistance so that it takes negligible current from the circuit. An ...

. In 1934 he founded Ballantine Laboratories, which he led until his death. There he developed improved techniques for measuring the performance of

microphone A microphone, colloquially called a mic or mike (), is a transducer that converts sound into an electrical signal. Microphones are used in many applications such as telephones, hearing aids, public address systems for concert halls and pub ...

s and

loudspeaker A loudspeaker (commonly referred to as a speaker or speaker driver) is an electroacoustic transducer that converts an electrical audio signal into a corresponding sound. A ''speaker system'', also often simply referred to as a "speaker" or ...

s, and most notably, the first

throat microphone A throat microphone, also called a laryngophone, is a type of contact microphone that absorbs vibrations directly from the wearer's throat by way of single or dual sensors worn against the neck. The sensors, called transducers, can pick up speec ...

for aircraft pilots. Ballantine held more than 30 patents, and was a Fellow of the American Physical Society, the

Acoustical Society of America The Acoustical Society of America (ASA) is an international scientific society founded in 1929 dedicated to generating, disseminating and promoting the knowledge of acoustics and its practical applications. The Society is primarily a voluntary org ...

, and the

Institute of Radio Engineers The Institute of Radio Engineers (IRE) was a professional organization which existed from 1912 until December 31, 1962. On January 1, 1963, it merged with the American Institute of Electrical Engineers (AIEE) to form the Institute of Electrical ...

, as well as a member of the

American Association for the Advancement of Science The American Association for the Advancement of Science (AAAS) is an American international non-profit organization with the stated goals of promoting cooperation among scientists, defending scientific freedom, encouraging scientific responsi ...

and the

Franklin Institute The Franklin Institute is a science museum and the center of science education and research in Philadelphia, Pennsylvania. It is named after the American scientist and statesman Benjamin Franklin. It houses the Benjamin Franklin National Memor ...

. He received the 1931 IEEE Morris N. Liebmann Memorial Award, the 1934

Elliott Cresson Medal The Elliott Cresson Medal, also known as the Elliott Cresson Gold Medal, was the highest award given by the Franklin Institute. The award was established by Elliott Cresson, life member of the Franklin Institute, with $1,000 granted in 1848. The ...

of the Franklin Institute, and the Radio Club of America's 1946 Armstrong Medal (posthumously). The Franklin Institute's

Stuart Ballantine Medal {{notability, date=February 2018 The Stuart Ballantine Medal was a science and engineering award presented by the Franklin Institute, of Philadelphia, Pennsylvania, USA. It was named after the US inventor Stuart Ballantine. Laureates *1947 - Ge ...

is named in his honor. Ballantine was president of the

in 1935.

Selected works

* ''Radio Telephony for Amateurs'', 1922

References

External links

Obituary, Proceedings of the I.R.E.

Proceedings of the IRE, Morris Liebmann Memorial Award

Biography by James E. Brittain

{{DEFAULTSORT:Ballantine, Stuart 1897 births 1944 deaths Drexel University alumni Harvard University alumni People from Philadelphia American acoustical engineers Radio pioneers 20th-century American inventors