Radar and Sonar: Wave Transmission and Applications

• Radar (Radio Detection and Ranging) and Sonar (Sound Navigation and Ranging) are remote sensing systems that rely on wave transmissions.

Wave Transmissions in Radar and Sonar

• Radar transmits electromagnetic waves.
• Sonar transmits acoustic waves.
• Both systems use echoes from waves to determine the size, shape, distance, and speed of a target.

Applications of Radar and Sonar

• Radar signals are best suited for surface and atmospheric observations.
• Sonar signals easily penetrate water, are ideal for underwater navigation and detection.

Early Radio Reflection Observations

• Leo C. Young and Dr. Alfred Hoyt Taylor made the first U.S. observations of radio reflection.
• Scientists detected radio wave reflections from aircraft eight years after initial discovery.

Development of Radar Technology

• From 1930 to 1940, the U.S. Naval Research Laboratory researched the use of radio for ranging and detection.
• In 1935, $100,000 was provided to the Naval Research Laboratory for radar development.
• The first U.S. radar, XAF, was permanently installed on USS New York (BB-34) in 1938.
• By December 7, 1941, 20 radar units were installed on selected ships
• Radar contributed to U.S. Navy victories in World War II, specifically at the:
  • Battle of the Coral Sea
  • Battle of Midway
  • Guadalcanal

Sonar Development

• Modern sonar development began in the 1920s with advancements in underwater sound applications.
• Ships developed depth sounding and echo ranging on submarines.
• Thomas Edison and others researched passive listening devices, while other researchers explored oceanography.

Sonar in World War II

• Sonar development accelerated during World War II due to German U-boat threats.
• German submarines rapidly torpedoed Navy-escorted convoys.
• Ships were being sunk faster than the U.S. could replace them, some near the U.S. eastern seaboard.
• Mobilization of the U.S. workforce and sonar development helped contain the U-boat threat.

Post-War Sonar Advancements

• In 1949, the Naval Research Laboratory detected submarines at 10–15 nautical miles using SOFAR hydrophones.
• Submarines could be detected several hundred miles away by the end of the year.
• Dr. Maurice Ewing established a SOFAR station in Bermuda in 1949.
• The Committee on Undersea Warfare of the National Research Council discussed a long-term program to counter the Soviet Union's submarine force.
• The Hartwell Committee was formed to conduct a broad study and considered the ability to transport people and goods crucial.

Hartwell Committee Recommendations

• Development of nuclear-powered submarines.
• Detection of submarines using real-time spectral analysis of radiated sound energy for antisubmarine warfare.
• Admiral Thorwald A. Solberg was directed to arrange a research and development program in low-frequency sonar with Bell Telephone Laboratories.

Key Factors in Sonar Development

• Discovery that low-frequency sounds travel great distances in the ocean.
• Realization that submarines radiate identifiable low-frequency energy.
• Bell Laboratories played an important role.

Explore remote sensing systems like Radar and Sonar, which use wave transmissions to determine target size, shape, distance, and speed. Radar, using electromagnetic waves, is ideal for surface and atmospheric observations, while Sonar, using acoustic waves, excels in underwater navigation and detection.