SCANFAR

SCANFAR was the first phased array radar system deployed by the United States Navy, developed by Hughes Aircraft Company in the late 1950s and installed aboard the nuclear-powered guided-missile cruiser USS Long Beach (CGN-9) and the aircraft carrier USS Enterprise (CVN-65), with operational capability achieved in 1962.^[1] The system was designed to provide superior multi-target tracking and surveillance compared to conventional rotating-antenna radars, enabling simultaneous monitoring of numerous airborne threats without mechanical scanning.^[1] SCANFAR consisted of two distinct radars: the AN/SPS-32, a two-dimensional long-range air search radar with a 400-mile detection range, featuring a large 40-by-20-foot antenna weighing 48.5 tons; and the AN/SPS-33, a three-dimensional target tracking radar with a narrower 25-by-20-foot antenna weighing 120 tons.^[1] Each radar utilized four fixed antennas mounted in a rectangular array to achieve 360-degree coverage, with the SPS-32 handling initial detection and the SPS-33 focusing on precise elevation and azimuth tracking for weapon guidance.^[1] Despite its pioneering role in electronic scanning technology, SCANFAR's deployment was limited to just two sets due to significant challenges, including its enormous size, high cost, and demanding maintenance requirements that strained shipboard operations.^[1] The system's antennas dominated the superstructures of both vessels, contributing to their distinctive boxy profiles, and it represented an early step toward more advanced integrated systems like Aegis.^[1] By the late 1970s, plans were underway to remove SCANFAR from the USS Long Beach during a mid-life modernization, reflecting the Navy's shift to more compact and reliable phased-array technologies.^[1]

System Overview

Components

The SCANFAR system comprised two primary radars: the AN/SPS-32, operating in the UHF band as a long-range air search radar equipped with four fixed planar arrays, and the AN/SPS-33, functioning in the S-band as a tracking radar with pencil beam capability and four fixed arrays.^[2]^[1] These radars featured a physical configuration of four billboard-style arrays per unit, each measuring approximately 25 feet high by 20 to 40 feet wide, mounted atop a large box-like superstructure to enable 360-degree coverage without mechanical rotation.^[1] Integration with supporting systems included high power requirements driven by vacuum tube technology, which demanded substantial electrical input and frequent maintenance due to tube failures.^[3] Essential cooling systems managed the significant heat generated by the vacuum tubes and transmitters, while basic analog signal processing hardware, characteristic of 1960s-era electronics, handled echo reception and initial data formatting.^[1]^[3] As a frequency-scanning phased array system, SCANFAR achieved beam steering by varying the transmitted frequency, which exploited the arrays' inherent dispersion to electronically direct the beam in elevation or azimuth without physical movement of the antennas.^[1]

Capabilities

The SCANFAR system, comprising the AN/SPS-32 search radar and AN/SPS-33 tracking radar, provided extended detection capabilities for naval air surveillance. The AN/SPS-32 achieved detection ranges of up to 400 nautical miles against large targets and approximately 200 nautical miles against fighter-sized targets under ideal conditions, enabling early warning of potential threats over vast ocean areas.^[1] The AN/SPS-33 complemented this by focusing on precise height-finding and target illumination for missile guidance. As a pioneering phased array system, SCANFAR offered significant advantages over traditional rotating antennas, including the ability to simultaneously track hundreds of targets in three dimensions—providing range, bearing, and altitude data—without mechanical movement.^[1] This was facilitated by rapid electronic beam steering through frequency scanning for elevation adjustments on the AN/SPS-32's fan-shaped beam, which covered wide horizontal sectors for initial search, and a combination of frequency and phase scanning on the AN/SPS-33's narrow pencil beam for accurate, operator-controlled tracking of individual threats.^[1] These features allowed for high-resolution performance against high-speed airborne and surface targets, enhancing defensive response times in dynamic combat scenarios. SCANFAR's integration with the Naval Tactical Data System (NTDS) further amplified its operational strengths by automating data fusion and distribution across networked ships, supporting real-time battle management such as air traffic control and coordinated strikes.^[4] This linkage enabled the system to process and share radar tracks via data links like Link 11, allowing operators to identify friend-or-foe distinctions and vector assets over hundreds of miles, marking an early step toward integrated command and control architectures.^[4]

Development

Origins and Design

The development of the SCANFAR radar system was initiated in the late 1950s by Hughes Aircraft Company under contracts from the U.S. Navy, aimed at equipping nuclear-powered surface combatants with advanced sensor capabilities.^[1] This effort aligned with the Navy's push toward nuclear propulsion for major warships, including the cruiser USS Long Beach (CGN-9) and the aircraft carrier USS Enterprise (CVN-65), to enhance detection and engagement in emerging high-threat scenarios during the Cold War.^[1] The primary design goals centered on creating a non-rotating, electronically scanned radar to enable superior multi-target tracking without the vulnerabilities of mechanically rotating antennas, such as susceptibility to jamming or mechanical failure in intense combat environments.^[1] SCANFAR was envisioned as a unified system that could handle both long-range search and precise tracking functions, supporting the integration of nuclear-powered platforms into carrier strike groups with heightened air defense requirements.^[1] Key milestones included prototype development beginning around 1958, with Hughes focusing on frequency-scanning phased array technology as a practical simplification over more ambitious true time-delay systems like the earlier AN/SPG-59 radar, which had proven overly complex for shipboard implementation.^[1] This approach allowed for beam steering via frequency shifts, reducing hardware demands while maintaining electronic scanning advantages. SCANFAR utilized similar frequency-scanning phased array technology being explored for systems like the AN/SPG-59 in the Typhon program. By 1962, the system was installed on the target ships, including USS Long Beach and USS Enterprise, marking the transition from experimental prototypes to operational hardware.^[1] As the lead contractor, Hughes Aircraft played a central role in integrating the search component (AN/SPS-32) and the tracking component (AN/SPS-33) into the cohesive SCANFAR package, ensuring compatibility with the ships' superstructures and associated command systems.^[1] This integration emphasized modularity and reliability for the demanding conditions of nuclear surface warfare.^[1]

Technical Challenges

The development of SCANFAR encountered significant reliability challenges, primarily stemming from its reliance on vacuum tube technology for the phased array elements.^[5] The AN/SPS-32 and AN/SPS-33 radars, which comprised the core of the system, suffered frequent failures and required extensive maintenance, often rendering the system inoperable for extended periods. These issues arose from the inherent limitations of vacuum tubes in handling the complex signal processing and beam steering demands of a passive electronically scanned array, leading to high downtime and operational frustrations aboard equipped vessels.^[5]^[1] Power and cooling requirements further compounded these difficulties, as the system's large antenna arrays demanded enormous electrical input and sophisticated thermal management. The passive design, with its vacuum tube amplifiers, resulted in exceptionally high power consumption, characteristic of early phased array systems and exacerbated by the need to drive numerous tube-based transmit/receive elements.^[5]^[1] This power intensity not only strained shipboard generators but also highlighted the trade-offs in scaling such technology for naval applications. Cost overruns plagued the program from inception, driven by the ambitious scope and unforeseen technical hurdles in fabricating the massive arrays. SCANFAR utilized core phased array principles similar to those in the AN/SPG-59 radar concepts from the Typhon missile system; however, even this approach exceeded budgets due to protracted development and the high expense of custom vacuum tube components. The total investment proved prohibitive, limiting production to just two installations and prompting early program curtailment despite its pioneering role.^[1]^[5] Early testing of prototypes revealed beam instability and control issues inherent to the analog beam steering mechanisms, necessitating multiple iterations to achieve basic functionality. Installed on USS Long Beach and USS Enterprise in 1962, the system underwent rigorous sea trials that exposed these flaws, including inconsistent tracking and vulnerability to environmental factors. Subsequent upgrades, such as the 33-IV modification to the AN/SPS-33 in the late 1960s and early 1970s, introduced solid-state low-noise amplifiers to replace some tube elements, enhancing reliability and reducing weight; yet, these efforts could not fully overcome the foundational limitations, leading to eventual replacement with more robust designs like the AN/SPS-48/49.^[1]^[6]

Deployment and Operation

Installations on Ships

The SCANFAR radar system, comprising the AN/SPS-32 long-range search radar and the AN/SPS-33 height-finding radar, was installed on two landmark U.S. Navy vessels as their primary sensor suite: the nuclear-powered guided-missile cruiser USS Long Beach (CGN-9) and the nuclear-powered aircraft carrier USS Enterprise (CVN-65). Both ships were commissioned in 1961, with SCANFAR integrated during their construction phases to serve as testbeds for this advanced phased-array technology.^[7]^[3] Hughes Aircraft Company led the installation efforts, embedding the system's four-faced antenna arrays into the ships' superstructures as part of the original design and fitting-out processes. On USS Long Beach, built at Bethlehem Steel's Fore River Shipyard, SCANFAR was fitted during initial construction, becoming fully operational by 1962 following shakedown trials. For USS Enterprise, constructed at Newport News Shipbuilding, the system was installed during the final outfitting stage before commissioning, leveraging the carrier's expansive island structure.^[6]^[7]^[3] To accommodate the bulky, billboard-style arrays—the AN/SPS-32 antennas measuring 40 by 20 feet and the AN/SPS-33 antennas measuring 25 by 20 feet—the ships underwent significant structural modifications that defined their distinctive profiles. USS Long Beach received a tall, box-like superstructure rising prominently from its amidships deck, which housed the radars and provided elevated vantage points for all-around coverage, though it increased the ship's topweight and required careful ballast adjustments. USS Enterprise's island was similarly expanded with a large, cubic enclosure atop the bridge levels, enlarging the overall silhouette and integrating the arrays seamlessly with the carrier's flight operations layout. These adaptations, while innovative, imposed notable demands on the vessels' stability and aesthetics.^[7]^[3]^[8]^[1] The integration process extended beyond the radars themselves, linking SCANFAR to the ships' Naval Tactical Data System (NTDS) computers for automated track processing and to the nuclear propulsion power plants for reliable high-voltage supply. This setup, powered by the C1W reactor on Long Beach and the A2W reactors on Enterprise, ensured uninterrupted operation of the power-hungry vacuum-tube-based electronics, marking SCANFAR as the cornerstone sensor for these inaugural nuclear surface combatants and enabling robust all-weather detection capabilities from inception.^[9]^[7]^[3]

Service History

The SCANFAR radar system underwent its first at-sea trials in 1962 aboard the USS Long Beach (CGN-9) and USS Enterprise (CVN-65), marking the initial operational testing of this pioneering phased-array technology in the U.S. Navy. These trials validated the system's long-range detection capabilities, with the AN/SPS-32 providing air search up to 400 nautical miles and the AN/SPS-33 enabling height-finding and tracking.^[10]^[3] Following successful integration, SCANFAR became operational on both vessels, supporting early Cold War missions such as Operation Sea Orbit in 1964, where the ships demonstrated global nuclear-powered endurance.^[10] SCANFAR entered combat service during the Vietnam War, with the USS Enterprise deploying to the Gulf of Tonkin in November 1965 to provide air defense for carrier operations. The system supported carrier air wings on Enterprise during combat patrols, offering real-time tracking for strike missions against North Vietnam and enabling positive identification of friendly and hostile aircraft within the Positive Identification Radar Advisory Zone (PIRAZ).^[3] The USS Long Beach followed in 1966, serving as a PIRAZ station and contributing to air defense by directing intercepts, including the downing of North Vietnamese MiG-21s in May and June 1968 using Talos missiles guided by SCANFAR data.^[10] Beyond Vietnam, SCANFAR tracked Soviet aircraft, such as Tu-95 Bears, during tense Cold War encounters in the 1960s and 1970s, enhancing fleet situational awareness.^[3]^[10] In operational scenarios, SCANFAR demonstrated effective multi-target tracking, handling dozens of simultaneous contacts for air defense coordination, but it frequently suffered outages due to the unreliability of its vacuum-tube electronics, which required constant maintenance and limited uptime.^[1]^[10] These issues persisted through the 1970s, when SCANFAR remained the primary radar on both ships, but interim upgrades—such as the 1967 conversion to solid-state electronics on Long Beach—improved reliability and reduced system weight by 20 tons, extending its viability for ongoing deployments.^[10]^[1]

Replacement and Legacy

Decommissioning

The decommissioning of the SCANFAR radar system marked the end of its operational life on U.S. Navy vessels, driven by technological and logistical considerations. The system was first removed from the USS Long Beach (CGN-9) during a mid-life overhaul at the Puget Sound Naval Shipyard from 1980 to 1983, where it was replaced by the AN/SPS-48 3D air search radar and the AN/SPS-49 long-range air search radar.^[10] On the USS Enterprise (CVN-65), SCANFAR began to be phased out during an extensive refit starting in January 1979 and lasting until February 1982, with replacement by AN/SPS-48 and AN/SPS-49 radars completed upon the refit's end in February 1982.^[3] The primary rationale for SCANFAR's retirement stemmed from its growing obsolescence amid advancing radar technologies. The system's reliance on vacuum-tube components contributed to significant reliability issues and high maintenance demands, with the AN/SPS-32 weighing 48.5 tons and the AN/SPS-33 weighing 120 tons, complicating upkeep and power consumption on ships.^[1] These factors, combined with escalating costs, made SCANFAR less viable compared to emerging solid-state radars, while conventional rotating antennas like the AN/SPS-48 and AN/SPS-49 offered comparable performance at lower operational and maintenance expenses.^[1] The transition also aligned with broader Navy efforts to standardize radar suites across the fleet for improved interoperability and cost savings. Refit processes for SCANFAR removal required careful engineering to dismantle the system's massive fixed-array structures without compromising ship integrity or extended downtime. On both vessels, the overhauls involved physically extracting the bulky phased-array antennas and associated electronics from the superstructure, often necessitating temporary modifications to maintain balance and radar coverage during the transition.^[1] New rotating radars were then integrated into redesigned island configurations, with efforts focused on minimizing disruptions to ongoing operations—such as scheduling work during planned availabilities—to ensure the ships could return to service promptly.^[3] By the end of the 20th century, no SCANFAR systems remained operational in the U.S. Navy fleet, as both host ships underwent final decommissionings—the USS Long Beach in 1995 and the USS Enterprise in 2017—with all components scrapped during these processes or earlier refits.^[3]

Influence on Future Systems

SCANFAR demonstrated the operational feasibility of fixed-antenna phased-array radars for naval applications, marking a pivotal shift from mechanical scanning systems to electronic ones in U.S. Navy warfare capabilities. As the first such system deployed on ships like USS Long Beach (CGN-9) and USS Enterprise (CVN-65) in the early 1960s, it proved that phased arrays could provide rapid beam steering and multi-target tracking without moving parts, influencing subsequent passive electronically scanned array (PESA) designs. This legacy directly contributed to the development of the AN/SPY-1 radar in the Aegis system, which adopted a more compact, multi-function phased-array architecture to achieve similar capabilities with reduced size and improved reliability.^[1] The system's challenges, including high maintenance demands due to its reliance on vacuum tube technology and massive antenna sizes (e.g., the AN/SPS-32's 40x20-foot array weighing 48.5 tons), underscored the need for advancements in solid-state electronics and more efficient beamforming techniques. These lessons informed the design of successors like the AN/SPY-1, which incorporated solid-state components to enhance reliability and reduce weight, enabling deployment on Ticonderoga-class cruisers starting in the 1980s. SCANFAR's operational temperamental nature, which led to its replacement on Long Beach with conventional radars like the AN/SPS-48 and AN/SPS-49, accelerated the Navy's push toward digital processing and integrated systems for better performance against evolving threats.^[1]^[11] Beyond specific radar evolutions, SCANFAR's multi-target tracking prowess—capable of handling numerous simultaneous engagements—influenced the broader architecture of modern air defense networks by validating the integration of radar with command-and-control systems. It spurred U.S. Navy investments in comprehensive combat systems like Aegis, which combined phased-array sensing with automated fire control to counter saturation attacks, a concept refined from SCANFAR's early demonstrations. This historical milestone not only bridged the gap between experimental arrays and fleet-wide adoption but also took over two decades to realize in a successful form, with Aegis achieving initial deployment in 1983.^[1]^[11]