John Hibbett DeWitt
John Hibbett (Jack) DeWitt junior (born February 20, 1906 in Nashville , Tennessee , † January 25, 1999 there ) was an American electrical engineer . He proved the permeability of the ionosphere for radio waves by using the moon as a reflector. Earth-moon-earth radio links use this principle .
Life
DeWitt was the son of Tennessee Appeals Court Judge John Hibbett DeWitt. Very early on he began to be interested in electrical engineering and especially radio technology . At the age of 16 he founded the first commercial radio station in Nashville, with which he broadcast from his parents' living room.
He took an engineering degree at Vanderbilt University in Nashville, but left it in 1929 without a degree to work at Bell Laboratories in Washington, DC . In 1932 he went back to Nashville to become chief engineer at WSM . In the same year he began to experiment with self-made telescopes with his brother Ward DeWitt .
After the start of World War II , he returned to Washington to work on radar improvements for the US military at Bell Laboratories and Evans Signal Laboratories . He had the rank of Lieutenant Colonel .
Shortly before the end of 1943, he was appointed director of Evans Laboratories . From 1945 he was in charge of the " Project Diana ".
In 1946, after he left there, he worked for a year as a consultant to the Clear Channel Broadcasting Service , which was trying to get approval for higher transmission powers for their stations.
The following year he became president of WSM in his hometown of Nashville. There he met the astronomer Carl Keenan Seyfert , who taught at Vanderbilt University . DeWitt helped him out with his self-made 30 cm reflector telescope , since the university only had a 15 cm lens telescope , which was also in the middle of the city. He also designed photometers for photoelectric photometry for Seyfert . His telescope is now on the roof of Vanderbilt University.
In 1968 he left WSM and went into retirement.
He was a radio amateur with the amateur radio call sign N4CBC. DeWitt was an IEEE Life Fellow for contributions to broadcasting and showing radar reflections from the moon. He was awarded the Legion of Merit for his collaboration in the development of the radar proximity fuse .
He was married twice and had a son, a daughter and a stepdaughter. He died at home in Nashville.
Project Diana
During his time at the Evans Signals Laboratory, a military research laboratory in Fort Monmouth, New Jersey , John DeWitt was appointed head of research into whether radio waves could penetrate the ionosphere . This was militarily interesting to locate missiles flying above them. DeWitt planned to use the moon as a passive reflector, so he named the project after Diana, the Roman goddess of the moon .
On January 10, 1946 at 11:58 a.m. the research group was successful, they heard the faint echo of their signal from the moon. For this they used an antenna with 64 interconnected dipole antennas and a transmitter with an output power of about 4000 watts, the frequency used was 111.5 MHz .
By proving that the ionosphere can be penetrated by radio waves, the cornerstone of radar astronomy was laid. This knowledge was also important for the beginning space travel , because communication with satellites and spacecraft had proven possible.
Web links
- Biography in International Amateur-Professional Photoelectric Photometry Communication , 03/1988, No. 31, p. 10, bibcode : 1988IAPPP..31 ... 10S
- Project Diana in the IEEE Virtual Museum ieee-virtual-museum.org
Individual evidence
- ↑ N4CBC in the Federal Communications Commission (FCC) database
| personal data | |
|---|---|
| SURNAME | DeWitt, John Hibbett |
| ALTERNATIVE NAMES | DeWitt, John Hibbett junior (full name); DeWitt, Jack (nickname) |
| BRIEF DESCRIPTION | American electrical engineer |
| DATE OF BIRTH | February 20, 1906 |
| PLACE OF BIRTH | Nashville , Tennessee , USA |
| DATE OF DEATH | January 25, 1999 |
| Place of death | Nashville , Tennessee , USA |