Jim Creek Naval Radio Station

Jim Creek Naval Radio Station is a United States Navy very low frequency radio transmitter facility at Jim Creek near Oso, Washington. The primary mission of this site is to communicate orders one-way to submarines of the Pacific fleet. Radio waves in the very low frequency band can penetrate seawater and be received by submerged submarines which cannot be reached by radio communications at other frequencies. Established in 1953, the transmitter radiates on 24.8 kHz with a power of 1.2 megawatts and a callsign of NLK, and is one of the most powerful transmitters in the world. Located near Arlington, Washington, in the foothills of the Cascades, north of Seattle, the site has 5,000 largely forested acres.

Much of the site is devoted to the enormous overhead wire antenna array that is necessary to efficiently radiate the VLF waves. The antenna, shown above, consists of ten catenary cables, 5,640–8,700 ft long, suspended in a zigzag pattern over the valley between Wheeler mountain and Blue mountain on twelve 200 ft. towers on the mountains' crests. Each cable receives energy from a vertical cable attached at the center, which drops down to the valley floor where it is fed by one of two "bus" transmission lines which extend along the valley from the transmitter building in the center.

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