Radio: Wave Focus

To U. S. pioneers in the old West, there seemed to be land enough for everybody. So, too, to radio pioneers there seemed to be wave lengths enough for all comers. Firstcomers, who had their pick, staked out their claims on the easy frequencies, the most readily exploitable wave lengths. Ultrashort waves (frequencies of 30,000 kilocycles and higher) were the wasteland. It was known that they were reliably effective only as far as the horizon, a paltry range for services which sought to blanket the whole earth.

Now radiomen are trying to conquer radio’s last frontier—the ultra-high frequencies. Most avid explorers of this wilderness are television engineers. But televisors cannot simply establish squatters’ rights, they must compete before the Federal Communications Commission with other services that seek room for expansion (TIME, July11). Meanwhile the inventors and engineers are concentrated on the problem of stretching this narrow field, increasing its effective range beyond the horizon. RCA-NBC boosted its television transmitter to the top of Manhattan’s Empire State Building, claims reliable reception for its experimental telecasts over a radius of 43 miles, receives reports of sporadic reception some 100 miles away.

For ultrashort waves do spray beyond the horizon. When they travel far, however, they become as shifty and unaccountable as ricocheting bullets, cannot be relied upon to hit any particular target. Radiomen are appalled at the cost of setting up a network of ultra-short-wave stations, piping programs from station to station by cable or ordinary short-range radio-relay links. Last week was announced the invention by RCA’s Inventor Vladimir Kosma Zworykin of a system designed to eliminate such costly cables.

As ultrashort waves pass through the atmosphere beyond the horizon, they encounter a constantly varying complex of atmospheric conditions. They are bent, reflected, shifted with every change in the constantly shifting atmosphere, like spray from a hose in the hands of a drunken gardener. Such waves hit a receiving antenna beyond the horizon only sporadically and by accident. The Zworykin invention, using two receiving antennae hooked up to a single receiving station, and an automatic device to match the wave length at the transmitter and receiver to the atmospheric conditions of the moment, is designed to assure unbroken, even, ultra-high frequency communication between a transmitter and one receiving station beyond the horizon. It would keep the uncertain spray steadily pouring on its objective.

Neither RCA nor Inventor Zworykin will predict the specific use to which this system will be put. They describe it as a “forward looking” invention which might be used to carry television programs to a relay station for rebroadcasting, or else for wireless telegraph communication. The equally forward-looking FCC is already nursing a headache over the prospective problem of assigning ultra-high-frequency wave lengths when each television station needs a slice of the radio spectrum six times as big as the total band of kilocycles now occupied by all U.S. broadcasting stations. This idea of an ultra-high-frequency transmitter which needs an even larger slice of the radio spectrum should make FCCommissioners scream for aspirin.