The 4 GHz Bandwidth Millimeter - Wave Radar

The landmark construction of the Advanced Research Projects Agency (ARPA)–Lincoln C-band Observables Radar (ALCOR) at Kwajalein Atoll in 1970 sparked significant interest in the ballistic missile defense (BMD) and satellite-identification communities [1]. ALCOR's 50 cm range resolution using 512 MHz bandwidth data confirmed the viability of valuable new BMD discrimination techniques and provided invaluable intelligence information to the space community. The revolutionary wideband range-Doppler images of satellites provided by ALCOR stoked a desire within the satellite-identification community for more and higher-resolution data. In addition, there was a strong need to image the increasing number of highly valuable satellites in the geosynchronous belt. In 1978, the Haystack Long-Range Imaging Radar (LRIR) was completed at Millstone Hill in Westford, Massachusetts, with a 1 GHz bandwidth X-band capability to image satellites with 25 cm range resolution at up to 40,000 km range [2]. It was the early success of ALCOR and LRIR that led to the next generation of higher-frequency wideband radars. Meanwhile in the BMD community, there was growing interest in gathering wideband signature data of reentry vehicles (RV) at millimeter wavelengths to better quantify the potential performance of millimeter-wave seekers on interceptors. The prospect of building a 35 GHz radar with sufficient sensitivity to collect useful RV data was unprecedented. Even if such a radar could be built, its beamwidth would be miniscule, posing a significant challenge to target acquisition. In 1979, Lin-coln Laboratory solidified plans for a Ka-and W-band ALCOR-adjunct radar that would take advantage of accu-The Millimeter-Wave Radar (MMW) on Roi-Namur is the highest resolution, highest metric accuracy radar at the Reagan Test Site on Kwajalein Atoll in the Marshall Islands. Originally designed as a 1 GHz bandwidth Ka-and W-band adjunct to the Advanced Research Projects Agency Lincoln C-band Observables Radar, the original charter for MMW was to provide a database of millimeter-wave signature data of missile reentry phenomenology. MMW has been upgraded several times over nearly 30 years of operations in response to evolving missions and requirements. Most recently, a 4 GHz bandwidth capability (33.0 to 37.0 GHz) was added that improves the radar image resolution to 6 cm, making MMW the highest-resolution coherent instrumentation radar in the world.