CXAM radar

CXAM radar
U.S. Navy · Public domain · source
Name	CXAM radar
Caption	CXAM air-search radar installation aboard a USS Saratoga (CV-3) in 1941
Country	United States
Introduced	1940
Manufacturer	Radio Corporation of America (RCA) and General Electric Company (GE)
Type	Air-search radar
Frequency	S-band
Range	up to 100 nmi (air targets)
Platform	Aircraft carriers, battleship, cruisers

CXAM radar was an early United States naval long-range air-search radar deployed aboard United States Navy capital ships and carriers in the early 1940s. Developed from experimental work by Naval Research Laboratory engineers and commercial developers such as RCA and General Electric Company (GE), the set provided crucial early-warning capability during the opening years of World War II. It bridged laboratory prototypes and later production sets used across the Pacific Theater and Atlantic Ocean.

Development and Design

Development began from research at the Naval Research Laboratory and associated projects with Massachusetts Institute of Technology and the Radiation Laboratory at MIT. Key industrial partners included RCA and General Electric Company (GE), working with Navy bureaus such as the Bureau of Ships and the Bureau of Aeronautics. Influences came from British radar efforts exemplified by Chain Home and radar scientists connected to Tizard Mission exchanges. Design work addressed shipboard constraints encountered on vessels like USS Lexington (CV-2), USS Saratoga (CV-3), and USS Enterprise (CV-6). Engineers drew on vacuum-tube transmitter developments seen in projects at Bell Labs and signal-processing ideas tested at Harvard University and Princeton University. Project management involved officers from Office of Naval Intelligence coordinating with industrialists such as David Sarnoff (RCA) and executives at General Electric Company (GE).

Technical Specifications

The CXAM operated in the S-band frequency range using high-power magnetron and klystron-derived transmitter technology similar to sets under development at Cavity Magnetron programs. Antennae were stabilized on masts and featured rotating arrays adapted to ship superstructures like those on USS Pennsylvania (BB-38) and USS California (BB-44). Signal processing used vacuum-tube receivers and cathode-ray tube displays influenced by oscilloscope advances at RCA laboratories. Electronics packages included recognitions from Western Electric component suppliers and cooling systems comparable to those in Douglas TBD Devastator avionics. Installation required integration with fire-control directors such as those produced by Ford Instrument Company and power supplies derived from shipboard generators used on Yorktown-class vessels.

Operational History

First installations appeared on fleet units assigned to Pacific Fleet and Atlantic Fleet task forces prior to Pearl Harbor attack. CXAM-equipped ships participated in early-war actions across the Coral Sea, Midway Atoll, and carrier battles involving units like USS Yorktown (CV-5) and USS Hornet (CV-8). Crews trained in shore schools at Annapolis, Maryland and at RADAR training schools established by the Navy with instructors from MIT Radiation Laboratory. Operational reports were relayed through chains involving Commander in Chief, United States Fleet and fleet commanders such as Admiral Ernest J. King and Admiral William F. Halsey Jr.. The capability influenced tactics tested in engagements near Solomon Islands and during convoy escort missions in cooperation with Royal Navy units.

Variants and Modifications

Field modifications were performed by fleet maintenance yards like those at Pearl Harbor Naval Shipyard and Norfolk Naval Shipyard. Subsequent production and improved designs led to derivatives used on destroyers, cruisers, and escort carriers; these successors traced lineage to designs produced by RCA and General Electric Company (GE). Modifications implemented lessons from battles involving USS Enterprise (CV-6) and USS Lexington (CV-2), with shipboard technicians and industrial engineers from Bethlehem Steel and contractors such as Western Electric adapting antenna mounts and receiver sensitivity. Later Navy radar series such as those by Mk 3 radar families incorporated improvements in frequency stability and pulse modulation inspired by CXAM experience.

Performance and Limitations

In service, CXAM provided early warning of incoming aircraft at ranges that exceeded the visual horizon, contributing to carrier group defense during operations near Midway Atoll and the Aleutian Islands Campaign. Limitations included size, weight, and maintenance demands driven by vacuum-tube reliability issues noted in reports to Bureau of Ships. Electronic countermeasures developed by adversaries and rapid advances at institutions like MIT Radiation Laboratory and Bell Labs soon outpaced CXAM performance; ships refitted with later models such as those influenced by SG radar and SC radar families reduced reliance on early sets. Operators contended with false returns in heavy seas and clutter conditions observed during operations in areas around Guam and Wake Island.

Preservation and Surviving Examples

A number of early CXAM components and documentation survive in collections held by institutions such as the Smithsonian Institution, National Air and Space Museum, and archives at Naval History and Heritage Command. Restorations and exhibits have involved curators from Naval Historical Center and collaboration with museums like Intrepid Sea, Air & Space Museum and USS Midway Museum. Surviving antenna assemblies and control consoles appear in naval technology exhibits alongside artifacts from World War II naval aviation, often interpreted in panels referencing figures like Frank Knox and operations involving Admiral Chester W. Nimitz.

Category:Naval radars