engineering

VLF Transmitter Cutler

VLF Transmitter Cutler is a engineering topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand VLF Transmitter Cutler rather than just read about it. In short: The VLF Transmitter Cutler is the United States Navy's very low frequency (VLF) shore radio station at Cutler, Maine. The station provides one-way communication to submarines of the Navy's Atlantic Fleet, both on the surface and submerged.

Key takeaways

VLF Transmitter Cutler belongs to engineering; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect VLF Transmitter Cutler to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of VLF Transmitter Cutler from memory before moving on to harder problems.

Reference excerpt

The VLF Transmitter Cutler is the United States Navy's very low frequency (VLF) shore radio station at Cutler, Maine. The station provides one-way communication to submarines of the Navy's Atlantic Fleet, both on the surface and submerged. It transmits with call sign NAA, at a frequency of 24 kHz and input power of up to 1.8 megawatts, and is one of the most powerful radio transmitters in the world.

Description The current Cutler Naval Station was built during 1960 and became operational on January 4, 1961. It has a transmission power of 2 megawatts. As with all VLF stations, the transmitter has a very small bandwidth, meaning it can only transmit coded text messages, at a relatively low data rate. The transmission consists of a continuously encrypted minimum-shift keying (MSK) signal capable of multi channel operations. The transmitter uses the frequency 24.0 kHz. During the past it used 17.8 kHz. The callsign of the station is NAA.

Antenna

The extensive antenna system consists of two separate identical specialized umbrella antenna arrays, designated the "north array" and the "south array". Each array has a tall metal mast in the center, surrounded by twelve more masts in two concentric rings of six, all supporting a network of horizontal cables. The cables are arranged to form six diamond-shaped (rhombic) "panels" radiating from the central tower at angles of 60°, so each array has a snowflake shape when viewed from above. Each panel is suspended from four masts: the central one, two in the inner ring, and one in the outer ring. The two arrays normally operate together as one antenna, but each is designed to function independently to allow the other one to be shut down for maintenance. The central mast of each array is 304 m (997.5 ft) tall. Six 266.7 m (875 ft) tall masts are at a radius of 556 m (1,825 ft) around it. The remaining six masts in the array are 243.5 m (799 ft) tall, at a radius of 935.7 m (3,070 ft) from the center. Each array's diameter is 6,140 ft (1.87 km; 1.16 miles); the station's transmission wavelength is about 12.5 km (7.76 miles). This type of antenna is called a trideco antenna. It functions as a capacitively top-loaded electrically short monopole. Vertical wires surrounding each central mast radiate the VLF radio waves, while the array of suspended horizontal cables functions as a large capacitor, increasing the efficiency of the vertical radiators. Under the antenna is a huge earthing system consisting of a radial network of cables buried in the ground, that serves as the bottom plate of the "capacitor". The climate in Maine results in severe icing of the antenna wires during the winter; the antenna structures cannot support the large increase in weight that this causes. Therefore, the antenna cables are connected to a deicing system. When in use, it heats the wires by running a 60 Hz electric current through them. The power required to deice one array within a reasonable time is 3 MW or more – considerably higher than the transmitter output power. An antenna array cannot transmit while it is being deiced, and one reason for having two arrays is to allow one array to be deiced while transmission continues uninterrupted on the other one.

Antenna maintenance Antenna maintenance is performed during the summer months. During maintenance periods the station transmits using one array while work is performed on the other array, which is grounded. This allows continuous transmission, crucial since the Navy closed Annapolis (NSS), the only other East Coast VLF station. The region where the two arrays come close together, near the transmitter house, is called the "bow-tie area". There are two panels and three towers from each array in this area. The fields on the grounded array are highest in the bow-tie area due to proximity to the active array. The present station operating procedure, based on a past RADHAZ survey, does not allow work on the bow-tie area towers or panels while transmitting either array. There is an ongoing tower painting project at Cutler scheduled for completion during the next few years. By the present station policy, completion of this project would require several months of total downtime. Test transmissions have been arranged, during which only four panels of one array are connected to the transmitter. The objective of the four-panel tests was to allow painting and normal maintenance on the bow-tie area towers of the array which is entirely inactive. A secondary objective of the tests is to characterize the antenna operating parameters which had not been measured since changing to 24.0 kHz.

See also Jim Creek Naval Radio Station Naval Communication Station Harold E. Holt Lualualei VLF transmitter Aguada transmission station List of masts

References

Illustrations

Worked examples

Example 1 — a first encounter with VLF Transmitter Cutler

Start with the simplest possible case. Write down what VLF Transmitter Cutler claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In engineering, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to VLF Transmitter Cutler before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about VLF Transmitter Cutler ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of VLF Transmitter Cutler

In research: VLF Transmitter Cutler appears in engineering research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses VLF Transmitter Cutler in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: VLF Transmitter Cutler is common in secondary-school and first-year university syllabi. It links to neighbouring topics Buildings and structures in Washington County, Maine, Communications and electronic installations of the United States Navy, Military equipment introduced in the 1960s, so understanding it makes those chapters shorter.
In everyday life: Look for VLF Transmitter Cutler outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study VLF Transmitter Cutler in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what VLF Transmitter Cutler means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain VLF Transmitter Cutler out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is VLF Transmitter Cutler in simple terms?

Why does VLF Transmitter Cutler matter?

Because it connects several engineering ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study VLF Transmitter Cutler?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on VLF Transmitter Cutler.