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ELF Station Republic, MI

Image from August 26, 2002 of U.S. Navy ELF station Republic, MI
U.S. Navy ELF transmitting station Republic, MI August 26, 2002 (from

The ELF transmitter site in Republic, MI was a cold-war era installation designed for ultra-covert submarine communications at speed and depth. Any short coded message could be transmitted one-way to submarines almost anywhere in the world with 76 Hz electromagnetic waves generated by oscillating over 2 million watts of electricity across over 84 miles of antenna lines in northern Michigan and Wisconsin.

Nuclear Deterrence

Nuclear Deterrence from

Since soon after the close of WWII and the development and widespread proliferation of nuclear weapons, it became clear that the only way to avoid a third world war and the subsequent destruction of the entire planet by nuclear annihilation was to practice extensive nuclear deterrence. Nuclear deterrence follows the assertion that no country would dare strike another with nuclear weapons while they knew that country could score a major retaliatory strike. This makes the survivability of a country’s nuclear capabilities of utmost concern. Any capability which can be easily taken out at the beginning of a nuclear conflict does not contribute to that nations nuclear deterrence, as it does not contribute to the country’s ability to perform a retaliatory strike.

Ballistic missile submarines were, and are still, considered some of the United States’ most survivable nuclear assets, as the enemy ought never to know where they are to be able to destroy them. Land-based assets are much more easily detectable, either by intelligence agents working domestically or by satellite surveillance.

As stealth is paramount to a submarine’s survivability, every effort must be taken to avoid detection by the enemy. In order to evade detection, it is best for the vessel to operate below the thermocline, a layer in the ocean which separates water of 2 different temperatures. This layer disrupts efforts to detect whatever is on the other side of it. However, there are very few communications techniques which allow messages to be sent to submarines below this layer. Extremely Low Frequency (ELF) is one of them. It is also imperative that the submarine stay as mobile as possible, as the enemy will not be able to hone in on its location. This combined requirement for communication at operational depth, speed, and with as much freedom of orientation as possible makes communication very difficult.

In order for the submarine to contribute as much as possible to the nations nuclear deterrence, it must be able to stay in constant communication with National Command Authority (NCA). These the only people who can release nuclear weapons, that is the president and the secretary of defense, or their successors. This is commonly referred to as Command and Control. Otherwise, even in the event of unrestricted nuclear warfare, the weapons aboard will remain dormant. Before the advent of ELF technology, the vessel would have to regularly surface, or at best deploy a buoy near the surface, exponentially increasing its likelihood of being detected and/or severely restricting its mobility. As spotted submarines no longer contribute substantially to the nation’s nuclear deterrence, it quickly became imperative to invent methods of communication which limit or remove entirely the effect of communication on the vessel’s detectability.

Range of ELF transmission based upon transmitter location from

Stated in a briefing on the ELF Communications System, by the office of Capt. Ronald L. Koontz, USN, the program manager for ELF communications, the mission of a ballistic missile submarine has 3 main objectives, as follows: “Remain undetected, maintain continuous communications reception, and maintain a condition of readiness which will ensure successful launch of all missiles if and when directed by NCA” (1, p. 4). The development of an ELF communications system helps these vessels accomplish all 3 parts of that mission, nearly anywhere in the world.


Because of the perceived need for increased nuclear deterrence during the 1970’s and 1980’s, there was widespread support among the defense community for implemented ELF technology. Admiral J. L. Holloway, III wrote in a letter to the Secretary of the Navy in March, 1977,

“I assure you that the need for Seafarer [ELF predecessor system] is real and urgent; that it works, and that there are no adequate alternatives for communicating with our submarines without their having to put an antenna near the surface and run the danger of detection. New technology is rapidly increasing this danger. To keep our submarines safe, we have to keep them deep and their antennas away from the surface. To keep our country safe against the threat of nuclear attack, we must assure the safety of our submarine force.” (2, p. 4).

Many people were especially worried about the increase in Soviet Anti-Submarine Warfare (ASW) capabilities with regards to the detection of United States’ ballistic missile submarines. These improvements are nearly meaningless if our submarines can stay below the thermocline, as would be possible with the widespread use of ELF communications. In 1980, Dr. Gerald Dinneen, the Assistant Secretary of Defense for Communications Command, Control, and Intelligence, responding to a question before the Senate Armed Services R&D Subcommittee said,

“We should go ahead now. Significant gains in Soviet ASW capabilities are possible during the next six to seven years, which is the time required to acquire a full scale operational ELF Communications system if we start right now … We must continue to improve our own capabilities, including ELF communications in order to maintain our technological advantage over the Soviet Union in submarine warfare.” (2, p. 4).

On behalf of those operating the submarines, and as someone who knew firsthand the danger inherent in operating a vessel in utmost secrecy, Vice Admiral R. Y. Kaufman the Director of Command and Control, Office of the Chief of Naval Operations, said the following in 1980 to the House Defense Appropriations Subcommitee,

“We, the operators, the people who have to make the ships work and do our jobs, who know the threat because it threatens us, have seen the flexibility it provides in operations and the increases in survivability it can provide for our missile submarines and we, without qualification, state that it is necessary and that we can find no alternative to ELF to do this job.” (2, p. 4).

Kaufman argues primarily from a human perspective, that United States’ ships and men would be in a lot less danger if ELF were to be implemented.

The United States Senate Committee on Armed Services (SASC) also presented support for Project ELF, mentioning specifically that tests already completed proved very promising, giving the project the most important vote of confidence of all, that of budgetary appropriation.

“The administration requested $58.5 million for continued research and development on the extremely low frequency system in fiscal year 1984. The elf communications system will enhance the survivability and effectiveness of our submarine force by allowing it to maneuver, transit, and perform its mission at operational speeds and depths without losing essential communications connectivity. The committee has strongly supported the elf program over the years during which the requirement for this system has been debated and redefined. The committee is pleased to note that recent tests of the reactivated extremely low frequency site have been most encouraging and reaffirms the committee’s confidence in the ultimate utility of this strategic communications system. The committee recommends the authorization of the requested amount for research and development of the elf system” (1 , p. 44).

Ultimately, President Ronald Reagan decided to support the project as well. In a 1981 memo to the Secretary of Defense, Caspar W. Weinberger, he wrote that he had

“advised the congress … to proceed with the ELF communications system deployment. The system will include upgrading of the existing ELF facility in Wisconsin, construction of a new transmitter facility … with 56 miles of antenna in Michigan, and elf receivers for submarines. … the navy should support this decision … that will provide an initial operating capability in … 1985.” (1, p. 2).

The project probably would never have been completed without his direct support.

ELF Station, Republic, MI

Generally, ocean water attenuates any electromagnetic signals with surprising efficiency. However, this efficiency drops off at low frequencies. Thus, for maximum penetration of ocean water and hence, the maximum operating range and depth for the system, an Extremely Low Frequency is required. The waves used, 76 Hz, have a wavelength of 2500 miles. For maximum antenna efficiency, the length of an antenna should approach the wavelength of the waves generated. However, ELF waves are so long that making an antenna large enough to approach this wavelength was entirely politically unfeasible. Thus, designers simply increased the input power to the antennas to over 2 million watts. Even with this amount of power, the waves generated by the transmitters have only 2 or 3 watts of power.

Display of the geographic placement of the two transmitters of Project ELF (from

The transmitter site in Republic, MI, called the Michigan Transmitter Facility (MTF), is the sister site to the Wisconsin Transmitter Facility (WTF), in Clam Lake, WI. Finished in 1988, this site completed project ELF, the downgraded version of the never completed Project Sanguine. ELF and Sanguine have several distinct differences. Unlike Sanguine, ELF was never designed to be survivable in the case of a nuclear strike. Sanguine was designed to have 6000 miles of antenna, taking up 20,000 square miles, 41% of the land area in the state of Wisconsin, using 240 transmitters and 800 megawatts of power.  By comparison, Project ELF takes up 8 acres, has 2 transmitters, and uses just over 2 megawatts of electrical input power. The two transmitters, Michigan and Wisconsin, are connected by an underground cable which allows them to work in concert, as 1 giant antenna, with 2 probes 148 miles apart, still a mere fraction of the generated wavelength.

Schematic of ELF Antenna Function (from

Each site has several above-ground wires running from the transmission station to giant grounding poles which each make up part of the antenna. The circuit is completed by currents traveling deep underground. The Upper Great Lakes region was chosen for these transmitters because of a peculiar geological formation, called the Laurentian Shield. This formation is a very large area of very low conductivity rock. The low conductivity of the rock forces the current loop created by each of the antennas to find a longer path to complete the circuit, increasing the effective length of the antennas and their efficiency.

Since ELF waves have such long wavelengths, their data transmission rate is very slow, to the point that it takes 10 to 15 minutes to send a single 3-letter code group. This means that rather than being able to send very specific instructions to a submerged vessel, such as release of nuclear weapons and targeting information in the event of direction by  National Command Authority, instructions to surface and communicate by other means would be sent via ELF. Even with this limitation, ELF capability gives a major boost to the command and control of ballistic missile submarines, as they can, with this technology, be alerted to surface for orders at once, rather than at the next scheduled report time. The skipper of the USS Batfish commented that the ELF system gave a “…significant improvement in submarine coordination, communication, command, and control” (1, p. 36).

ELF Termination

After the Collapse of the Soviet Union in 1991 the need for nuclear deterrence diminished significantly. By the first session of the 104th congress, in 1995, a bill was submitted by Russ Feingold, of Wisconsin, to shut down the ELF program entirely. He has the following to say about the program, “Did Project ELF play a role in helping to minimize the Soviet threat? Perhaps. Did it do so at risk to the community? Perhaps. Does it continue to play a vital security role to the Nation? No” (3, p. S232). Feingold does not argue that ELF was not useful during the cold war, merely that it can no longer be justified by the soviet threat, as the USSR has dissolved.

Though project ELF was never shut down by any act of congress, the Navy unilaterally decided to shut down the program on September 30, 2004 as it was outdated and unnecessary (4). With the decreased security concerns submarines could now again regularly surface for instruction from their chains of command without having to overly fear detection by the USSR. Additionally, improvements in VHF technology diminished the chance of detection as submarines came near to the surface, within range of communications. In many respects, the need for nuclear deterrence was severely diminished. As such, the ELF stations in Republic, MI and Clam Lake, WI were no longer necessary.

In the end, the Republic, MI ELF station operated for 36 years in defense, through nuclear deterrence, of the United States and her allies.

Primary Sources:

  1. Office of Capt. Ronald L. Koontz, Program Manager ELF Communications. (1984). “ELF Communications System“.
  2. General Telephone & Electronics Corporation. (1982). “Information about ELF Communications“.
  3. Feingold, Russ. (1995). “Extremely Low Frequency Communication System Termination and Deficit Reduction Act“. Congressional Record  – Senate – January 4, 1995 141.1: S231- S232.
  4. The Nuclear Resister. (2004). “Project ELF Closes“. The Nuclear Resister: 135.

Secondary Sources:

  • Heppenheimer, T. A. (1987). “Signaling Subs”, Popular Science 230.4: 44-48.
  • Naval Electronic Systems Command (1981). Extremely Low Frequency (ELF) Communications Program In Wisconsin and Michigan, System and Site Definition, Program Plans, Environmental Summary and Supplemental Information. Washington, D.C.
  • Marshall, Eliot (1983). “ELF Finally Wins a Vote”, Science 221.4611: 630-631.
  • Altgelt, Carlos. “The World’s Largest “Radio Station“. The Broadcaster’s Desktop Resource.
  • Marshall, Eliot (1981). “ELF Resurrected after Drwoning by Navy”, Science 212.4495:644-645.
  • O’Laughlin, Terry (1988). “The ELF Is Here!”, Popular Communications

Further Reading: