Paul Johannessen, radio-navigation innovator

PAUL JOHANNESSEN

Paul Johannessen twice retired from Megapulse Incorporated, the radio-navigation equipment manufacturer he founded in 1970, but it was not enough to keep him away.

Each day, he drove to the North Billerica headquarters and walked through to see what was new, working what his son called half time. He could still solve issues that occasionally stumped his staff. Just recently, he fixed a problem with a transmitter.

"He basically worked up until the day he died and continued to innovate," said his son, Erik, of Bedford, the president of Megapulse.

Dr. Johannessen was at home in Lexington on June 26, watching Wimbledon coverage on television, when he died of a heart attack, his son said. He was 81.

His work with Megapulse made a lasting impact in the field of navigation equipment, specifically the evolution of the Loran radio-navigation system, his family and colleagues said.

The son of a milkman, Paul Romberg Johannessen was born in Oslo in 1926. When he was a teenager, Nazi Germany invaded and occupied Norway.

At 17, Dr. Johannessen met his future wife, Astrid, and the couple began dating. In 1949, he received an engineering degree from Schou's Institute of Technology in Oslo, and then decided to move to the United States to attend the Massachusetts Institute of Technology.

He made the trip alone, however, asking his fiancé to wait until he completed a semester before she joined him. In December he wrote to her - "everything's fine; you can come over," the note said, according to his daughter Nina of Lexington. Shortly after she stepped off the boat in New York, the couple were married in a Lutheran church in the city.

Dr. Johannessen earned his master's degree and doctorate in electrical engineering from MIT in 1953 and 1958, respectively. During his time there, he also worked in the Servomechanisms Laboratory and taught courses in feedback control principles, elementary circuit theory, and feedback control theory and applications as an assistant professor.

In 1959, Dr. Johannessen joined General Telephone and Electric's Sylvania Applied Research Laboratory in Danvers. He headed work on high-power servo systems, automatic systems that use error-detecting feedback to correct their performance. While working in that lab, his research into control theory and non-linear circuit techniques led to the development of a high-power, all-solid state Loran-C transmitter that would become the focus of Megapulse, his son said.

First, however, he and several associates formed the consulting partnership Symbionics in early 1970. While a consultant, he developed the concept for Megapulse, his son said.

"There were seven or eight companies that spun out of Symbionics, and Megapulse was the only one that lasted," he said.

The company, and his work from then on, was dedicated to Loran-C solid-state transmitters. An acronym for Long Range Navigation, Loran is a radio-based navigation system that uses low-frequency radio signals from transmitters around the world to determine the position and speed of ships, aircraft, and land vehicles, according to Megapulse's website.

The technology was developed during World War II, and used by the United States and British militaries. In the years that followed, it became more common on crafts used for oil surveying exploration, recreational boating, and commercial fishing, according to Dr. Johannessen's son.

"It was the predecessor system to GPS," he said. Though many people thought Loran-C would become obsolete as GPS became more widespread, the government recently decided to modernize Loran and make it the official backup system, he said.

Throughout his career Dr. Johannessen continued to improve the Loran system. Megapulse is credited with several breakthrough Loran technologies, including a Loran data channel for the wide-area broadcast of differential GPS, according to the company's website. Dr. Johannessen was awarded 25 patents for his work, the most recent one on June 24, his son said.

His contributions to navigation science were recognized in 1993, when he was awarded the Thurlow Award from the Institute of Navigation. He retired from full-time work in 1999.

Dr. Johannessen was also a lifelong tennis playerbut said he would take up golf when tennis became too physically demanding. He made the switch about six years ago, quickly taking to golfing with his wife in Naples, Fla., where they spent the winter.

"He was a guy that loved every minute of his life," said his daughter Nina.

In addition to his wife, son, and daughter, Dr. Johannessen leaves a granddaughter and five grandsons; and a sister, Anne Marie Frivoll of Norway.

A service will be held at a later date.