Since the 19th century, people have developed systems of communicating information through space with the use of antennas which can transmit or receive radio waves. Any device which receives or transmits radio waves needs an antenna to either collect waves in the electromagnetic field and recreate an electrical signal, or to convert an electric current through the electromagnetic field to create radio waves for transmission. Antennas are widely used today in various electronic devices such as mobile phones, televisions, wireless data networks or remote controls.
The design of antennas are largely specific to the type of wireless communication system in which they are being used. Antennas may be specially constructed in order to direct radio signals in specific directions or to achieve a specific radiation pattern for improved signal strength. In some instances, especially in personal medical care or military applications, antenna design is often just as interested with the form of the device as it is with the ability to transmit or receive signals. For instance, external antennas which could increase aerodynamic drag are not ideal for certain types of aircraft.
Thanks to the work of Howard S. Jones, Jr., one of the 2018 inductees into the National Inventors Hall of Fame, the United States was able to advance antenna technology in the latter part of the 20th century. Jones’ innovative work in developing conformal antennas has been crucial for the development of enabled enhanced capabilities for spacecraft, rockets and other aeronautical technologies. This March 1st marks the 41st anniversary of the issuance of the U.S. patent for which Jones has been inducted into the Hall of Fame. Today, we return to our Evolution of Technology series to explore the early development of antennas and see how Jones was able to make a great step forward in improving our nation’s defense systems.
Hertz, Marconi Lead the Early Generation of Antenna Technology
The modern development of antennas to transmit radio waves goes back to at least 1886 when German physicist Heinrich Hertz proved the existence of electromagnetic waves; such waves had been theorized by Scottish mathematical physicist James Clerk Maxwell. Experimenting with a pair of spirally-wound conductors known as Riess spirals, Hertz noted that an electrical charge applied to one of the conductive coils resulted in the other coil forming a spark. Hertz would later refine his experiment to create a dipole antenna receiver, a type of receiver using two conductive elements in a symmetrical construction; “rabbit ear” antennas for older television sets were a form of dipole antenna.
The 20th century saw some huge advances in radio communications thanks to the development of new antenna technologies made just a few decades after Hertz operated the first antenna. In December 1901, Italian inventor and electrical engineer Guglielmo Marconi sent the first trans-Atlantic wireless radio wave transmission between England and the Canadian province of Newfoundland. Marconi’s wireless transmission system utilized monopole antennas, a straight-rod conductor which is vertically mounted over a ground plane conductive surface. At the turn of the 20th century, famed Serbian-born American inventor Nikola Tesla was also involved in the early development of the wireless transmission of electrical signals. The patents held by Marconi and Tesla in the area of wireless transmission technologies would actually be the focus of a patent case decided by the U.S. Supreme Court in 1943, where Marconi’s patent was held invalid as anticipated.
The first half of the 20th century would see continued growth in antenna technologies. Such advances were found very useful for keeping the lines of communication open during military combat. The development of antenna arrays, sets of antennas which are combined in order to achieve high gain, or directivity, as well as a narrower signal beam, found important applications in air defense systems during World War II. However, there were significant drawbacks to the use of antenna technology at that time, especially the fact that they were typically installed externally. This greatly added to the costs and complexity of using antennas in precision guidance systems for aircraft as external antennas would create drag.
Howard S. Jones, Jr., Develops Conformal Antennas for Army Missiles and NASA Spacecraft
Born in August 1921 in Richmond, VA, Howard S. Jones, Jr., would earn his undergraduate degree in mathematics and physics from Virginia Union University in 1943. Multiple accounts of Jones’ career indicated that he attended Virginia Union University at the urging of his mother and found that he had a propensity for scientific subjects while studying at that school. Upon graduating, Jones would serve for two years with the U.S. Army in WWII as a Signal Corps specialist in Japan and taught mechanical engineering subjects to Army officers.
Jones declined the opportunity to serve as an Army officer after WWII and instead chose to work as a researcher at the Ordnance Development Division, later known as Harry Diamond Laboratories, of the National Bureau of Standards, now the National Institute of Standards and Technology (NIST). Jones’ research work focused on antenna technology and he received 31 patents during his 34-year career at the Army research lab. By the mid-1970s, Jones was working on solving the problem of external antennas creating drag on missiles and rockets. Antennas were important not only for high-precision guidance systems but also to receive electronic detonation signals over a long distance. Working with copper wire, Jones was able to develop antenna arrays which conformed to the shape of missile casings and aircraft exteriors, reducing drag, weight and costs while also improving the performance of the antenna.
The patent which saw Jones inducted into the National Inventors Hall of Fame is U.S. Patent No. 4010470, titled Multi-Function Integrated Radome-Antenna System. Issued on March 1st, 1977, it claimed a radome-integrated conformal parallel plate radiator for a projectile which was comprised of a dielectric radome shape to conform to the forward portion of the projectile, a metallic ground plane formed on the interior wall of the dielectric radome, and a wedge-shaped metallic coating means deposited on the exterior wall of the dielectric radome and electrically short-circuited to the metallic ground plane means. The resulting invention provided a radar antenna system utilizing radiator elements to occupy none of the space interior to the radome, or domed enclosure for a radar antenna, which was capable of achieving a multitude of radiation patterns and could take the form of any projectile configuration.
Howard Jones’ conformal antenna arrays have been incorporated into aircraft for both military and space applications, including the Patriot guided missile and NASA’s Voyager spacecraft. Before retiring in 1980, Jones became the chief of the Harry Diamond Lab’s microwave research and development division. Jones became the 1985 recipient of the IEEE’s Harry Diamond Memorial Award for his developments in microwave conformal antennas and millimeter-wave components. In 1999, Jones was inducted into the National Academy of Engineering. He would go on to serve as a consultant for about two decades after his retirement. During his life, he published more than 40 technical articles, contributing a great deal to society’s overall knowledge of microwave antennas.