Editing Midway Atoll (section)

==== Eastern Island ====
[[Nomoi Islands|Eastern Island]], part of Midway Atoll, played a significant role during the [[Cold War]] as a site for U.S. naval intelligence operations. From July 1, 1954, to February 1971, it hosted the Naval Security Group Activity (NSGA), Midway Island, which was responsible for operating the AN/GRD-6 High-Frequency Direction Finding (HFDF) system. This system was integral to both the Eastern and Western Pacific HFDF networks, providing critical capabilities in tracking and monitoring high-frequency radio communications.

The AN/GRD-6 HFDF system was designed to automatically provide [[azimuth]] indications within the frequency range of 2 to 32&nbsp;MHz. It featured two antenna arrays: a low-frequency array covering 2 to 8&nbsp;MHz and a high-frequency array covering 8 to 32&nbsp;MHz. Each array consisted of multiple [[Monopole antenna|monopole]] antennas arranged in a circular pattern, with a sense antenna positioned at the center.<ref name=":2">{{Cite web |title=AN/GRD-6 DF Set |url=https://jproc.ca/rrp/grd_6.html |access-date=2025-03-29 |website=jproc.ca}}</ref> Beneath each array, a circular copper wire mesh ground mat was buried to ensure consistent and reliable direction-finding performance, independent of local ground conductivity.<ref>{{Cite web |title=AN/GRD-6 HF Direction Finding System (HFDF) |url=https://navy-radio.com/grd6.htm |access-date=2025-03-29 |website=navy-radio.com}}</ref><ref name=":2" /> The system included [[Superheterodyne receiver|superheterodyne]] receivers and cathode ray tube indicators to display the direction of incoming signals.<ref name=":2" />

The strategic location of Eastern Island allowed the NSGA to monitor vast expanses of the [[Pacific Ocean]], contributing to the [[United States Navy|U.S. Navy's]] efforts in signals intelligence and maritime surveillance during a period marked by heightened geopolitical tensions. The data collected through the AN/GRD-6 system supported various military operations and enhanced the United States' situational awareness in the region.

[[File:NSGA Midway Sign.jpg|thumb|NSGA sign 1970.]]

[[File:NSGA, Eastern Island 1970.jpg|alt=|thumb|NSGA Eastern Island 1970]]