Next time you feel put out because you have to reach out the window to clean a connection on your radio antenna lead in, give a thought to the problems which confront the Navy men who operate the Naval Radio Station at Haiku, Hawaii. Theirs is the job of maintaining an antenna array which stretches 7,500 feet across a valley at a height on either end of 2,000 feet above the ground. No masts are needed to support the five radiators in the array. The Navy suspended the wires by simply anchoring them at either end on the tops of two mountains which form a mile-wide box canyon.
From the valley floor, the five antennae overhead are almost invisible, and the huge twenty foot anchor insulators appear as tiny dots against the clouds. Nothing can be seen of the actual anchor sites on the tops of the mountains.
Construction of the unique antenna system was begun early in 1942 when the Navy faced the need for a high-powered low frequency transmitter to communicate with Navy raiders on their distant forays into the Japanese home waters. The breadth of the valley suited the requirements for a resonant antenna to radiate low frequency signals with maximum efficiency. By the summer of 1943 Radio Haiku was in operation, and the whine of its 200,000-watt alternator replaced the eerie voices of ghostly warriors of the past who, according to Hawaiian lore, had made the haunted valley of Haiku their headquarters.
In addition to the 200,000-watt alternator transmitter, the station has a 50,000-watt vacuum tube transmitter. The transmitters feed the six miles of antennae through 1,250- foot vertical leads to the center of each of the five spans of antenna.
This installation is one of the Navy’s largest and most powerful low-frequency transmitting stations.
In addition to its constant communications with the raiders, the station served to augment the regular Navy communications to far-flung Pacific Fleet and island bases.
Each of the stainless steel, copper-sheathed antennae is about 1-inch in diameter. They are connected to the 7/8-inch anchoring cable by a series of insulators totalling almost twenty feet. The outer ends of the over-all insulators are protected by corona shields which are about 3 ½ feet in diameter.
The vertical leads are built in the form of eight-wire cages, the wires being riveted to 6-inch spacer rings. One-ton counterweights, attached to the bottom of the vertical leads with 300 feet of cable, compensate for the swing of both the antenna and the vertical leads.
The largest transmitter is multiple-tuned, having four 125-ampere coils; one for each of the four main antennae. When using only one antenna, the transmitter can load that antenna with 450 amperes at 130,000 volts.
The generator for the larger transmitter is driven by a 600 horsepower electric motor. For emergency operation the station has a 1,000 horsepower diesel engine which drives a 750 KW generator—enough to supply power for both transmitters and the entire installation.
Every Monday, rain or shine, and it rains almost every day in winter, the maintenance crews climb into the cage-cars at the valley floor and are whisked to the top of the cliffs for a check of the anchor sites and the high frequency relay station. The cable cars make the 2,000-foot ascent in about eight minutes, but there is also a stairway built to the summit almost straight up from the valley floor. During the war a Marine climbed the stairs as fast as he could “just to keep in condition.” His time for the backbreaking climb, two and a half hours, is a record that has not been equalled.
From the cage-car landing, a concrete anchored steel ladder threads its way along the three foot wide razor-back summit to the high frequency relay stations which relays line-of-sight transmissions from stations on one side of the island to receivers on the other side. Buffeted by high winds and as often as not enveloped in fog, the ladder provides an awe-inspiring stroll. Two thousand feet down, through an occasional hole in the clouds, the buildings of the radio station and the banana plantations appear in miniature.
From this vantage point, the antennae stretch down and across the valley into nothingness. They become invisible long before they begin to curve upward to the anchors on the opposite cliff.