Tag Archives: Clear Channel

AM Radio History: 80th Anniversary of the “Havana Treaty,”

Radio World: History of Directional AM Broadcast Antennas

Many thanks to SWLing Post contributor, Marty, who shares the following article by John Schneider in Radio World:

In the early years of AM radio broadcasting, all stations utilized non-directional antennas. Most all of these were wire antennas suspended between towers or buildings. Interference, especially at night, was severe. An interfering signal of 5% or less in signal strength was enough to disrupt reception of the desired station, and if the frequencies of the two stations were slightly separated, there would be a heterodyne beat note. As a result, only a few widely-spaced stations could operate on each of the AM broadcast channels in the entire country at night. This limited the number of stations that could coexist to about 500 nationwide, with many of them sharing time on a single frequency.

As antenna technologies were developed and improved in the early 1930s, a few progressive stations began experimenting with multi-element directional arrays. This approach offered two attractive benefits: 1) It could reduce radiation towards other stations on the same or adjacent frequencies, permitting more stations to share a frequency; and 2) a broadcaster could direct more signal towards the desired coverage area, and away from wasted areas such as open water in the case of coastal stations.

WFLA-WSUN

The first known use of a directional antenna was by a pair of stations in Tampa/St. Petersburg, Fla. In 1927, the Clearwater Chamber of Commerce acquired station WGHB and changed the call sign to WFLA. A companion station, WSUN, was operated by the St. Petersburg Chamber of Commerce. The two stations shared the frequency of 900 kHz, broadcasting on alternate evenings to promote tourism and business opportunities in their respective communities. In reality, they operated with two station licenses, but there was only one transmitter and one antenna.[…]

Click here to to continue reading the full article in Radio World.

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Peter Tannenwald asks, “Are we really ‘revitalizing’ AM?”

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(Source: RadioWorld via Bill Patalon)

On AM revitalization, Peter Tannenwald asks, Are we really “revitalizing” AM, or are we walking around in circles?

Late on Friday, October 5, the Federal Communications Commission (“FCC”) released a Second Further Notice of Proposed Rulemaking in a five-year ongoing effort to “revitalize” the AM radio broadcast service. The new proposals continue a trend toward allowing higher power operation by smaller stations, by reducing nighttime signal protection for some 60 Class A AM stations located in the continental United States and 16 stations in Alaska. The end result would be less wide area coverage and more local radio service to the public.

To understand why the FCC is considering this action, it helps to understand a bit of the science behind AM signal propagation. AM radio signals travel through both the ground and through the air. At night, the airborne signal component (“skywave”) is reflected back to the earth from the ionosphere — a layer of the atmosphere extending from about 50 to 600 miles above the earth’s surface. The reflected signals may come back down to earth hundreds, if not thousands, of miles away from a station’s transmitter. Class A AM stations — formerly known as “clear channel” stations (no relation to Clear Channel/now iHeartMedia) — are powerhouses, transmitting with 50 kilowatts of power 24 hours a day – 200 or more times the power of the smallest AM stations.

[…]Signal reflection doesn’t work so well during the day, so the FCC has allowed other stations to occupy the Class A frequencies in other markets. But those stations have to curtail power during “critical hours” (two hours before sunrise and after sunset) and often have to reduce power to nearly nothing or shut down altogether at night. In today’s 24-hour-a-day, nonstop world, not being able to reach an audience at night is a losing proposition; so the FCC has yielded to constant pressure over the years to allow more power and longer hours of operation by those “other” stations, at the expense of long distance reception of Class A signals.

Now the FCC is proposing to go further, rolling back some previous restrictions on non-Class A AM stations and perhaps eliminating whatever remains (and it’s not much) of the protection of far-away reception. Under the proposals, which are sufficiently complicated that you should talk to your engineer if you really want to understand the details, Class A AM stations would be protected only within a higher strength signal contour (and so within a smaller area) than they are now; at least some, if not all, skywave protection would be eliminated.[…]

Click here to read the full article at RadioWorld.

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FCC might reduce AM clear channel power

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(Source: Tom Taylor Now)

Are the protected night signals of monster 50,000-watt AMs “an anachronism?”
And is the FCC poised to do something that will frustrate late-night DX’ers? The Commission tries again to balance the role of Class A signals like KMOX St. Louis/1120, designed to serve listeners hundreds of miles away, with the desires of local AMs. The “skywave” debate is decades-old – but particularly urgent now, given the rising noise floor from all kinds of interference. The Commission just issued a “Second further notice of proposed rulemaking,” noting the rise of “FM stations, satellite radio and other media.” The first notice drew “a voluminous and diverse set of comments,” with some pointing out that “AM skywave service is sporadic and unreliable, often subject to overwhelming environmental interference, and unlikely to consist of programming tailored to the needs of distant communities.” But then there are questions about hurricane and other weather/safety warnings. In this notice, the Commission has ideas about changes to daytime, “critical hours” operation after sunrise and before sunset, and “nighttime hours.” One observer tells this NOW Newsletter says that cutting through the thicket of details, “It’s clear that there will be a further reduction in protection to the clear channel Class A stations, particularly at night. The main questions are how much protection they will retain.”

Click here to read at Tom Taylor Now.

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iHeartMedia may collapse under debt

When WLW was the one and only “Super Station”

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WLW’s diamond-shaped Blaw-Knox radio tower at night (Original photo by RP Piper via Creative Commons 2.0)

(Source: National Endowment for the Humanities)

For a Brief Time in the 1930s, Radio Station WLW in Ohio Became America’s One and Only “Super Station”

by Katy June-Friesen

When President Franklin Roosevelt, sitting in the White House, pushed a ceremonial button on his desk in May 1934, a five hundred thousand-watt (500 kW) behemoth stirred in a field outside Cincinnati. Rows of five-foot glass tubes warmed. Water flowed around them at more than six hundred gallons per minute. Dozens of engineers lit filaments and flipped switches, and, within the hour, enough power to supply a town of one hundred thousand coursed through an 831-foot tower.

Thus began WLW’s five-year, twenty-four-hour-a-day experiment: a radio station that used more power and transmitted more miles than any station in the United States had or would. The so-called super station—licensed by the new Federal Communications Commission (FCC) on a temporary basis—amped up the debate among broadcasters, government regulators, and listeners about how radio should be delivered to serve the “public interest,” a mandate laid out in the Radio Act of 1927, and influenced legal, programming, and technical decisions that shape the broadcast system we know today.

Since radio’s beginnings in the early 1920s, industry and government leaders promoted it as the great homogenizer, a cultural uplift project that could, among other things, help modernize and acculturate rural areas. The challenge was how to reach these areas, many of which received few or no radio signals in the mid-1930s. One solution was high-powered, clear-channel stations that could blanket large swaths of the country with a strong signal. These stations operated on “cleared” frequencies that the government assigned to only one station to prevent interference.

WLW had operated on one of forty designated clear channels since 1928. The station’s creator and owner, an entrepreneur, inventor, and manufacturer named Powel Crosley Jr. frequently increased the station’s wattage as technology and regulation allowed. In 1934, when WLW increased its power from 50 kW to 500 kW, all other clear-channel stations were operating at 50 kW or less. Now, WLW had the ability to reach most of the country, especially at night, when AM radio waves interact differently with the earth’s ionosphere and become “skywaves.” People living near the transmitter site often got better reception than they wanted; some lights would not turn off until WLW engineers helped rewire houses. Gutters rattled loose from buildings. A neon hotel sign near the transmitter never went dark. Farmers reported hearing WLW through their barbed-wire fences.

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