is part of a Radio World series in which we share industry
opinions about AM revitalization.
thing about the medium waves is that there isn’t very much you can
do with them.
controls, high data rate links, phone calls are all rather useless at
MW. Unlike UHF, no one wants to pay anyone to clear out any chunk of
any spectrum below 3 MHz for any new technology or service. The whole
MW band (300 kHz–3 MHz) is less than half the bandwidth of a single
seems as if virtually half of all the noise in the entire radio
spectrum lands in MW. Efficient MW antennas inconveniently measure in
the hundreds of feet.
was reinvented at least once before. The original 1920s link budget
had a few 250 Watt class transmitters on clear channels being
received by long-wire antennas strung up to the silos on radio quiet
land. The current link budget is kilowatts being received on ferrite
loops and tiny wires buried in windshield glass.
MW’s good traits are a mixed blessing.
night, MW stations can cover the continent. Good if there are
desolate places to reach and few stations (think agricultural 1930
America) … not so good if that coverage is just interference for
other stations (think today, post urbanization and AM’s birth
and UHF are much better behaved. They better stay in their markets,
are high fidelity with low noise, and exhibit good penetration (MW’s
aperture effect won’t even let it go under a bridge or through an
far, any attempt to “compatibly fix” the AM band with digital
technology loads two adjacent channels with digital noise for
everyone that it attempts to save, and it doesn’t seem to work that
well at distances at night. Any conversion to all-digital would make
zillions of radios into decorative furniture.
listeners looking for more stations to listen to can get an infinite
number via the Internet right now, making the idea of running out to
buy a new digital MW radio feature seem unreasonable. Oddly enough,
if one just has to have more broadcast stations, and too
stations aren’t necessarily a good thing, the old TV spectrum
adjacent to the FM band is much underused.
let’s just agree that trying to make MW into something that can
compete with VHF, Internet and satellite is … well … as silly as
building in a flood plain and expecting to not float away
periodically. However, moving all AM stations to the old and much
underused VHF TV slots works just fine.
it be that unwinding the MW/AM service with the goal of providing a
few simulcast (from their new VHF allotments), wide area coverage and
some really very accessible community low-power services is a more
desirable revitalization of the MW band?
would do two other things with the MW/AM band.
I’d provide space for a low-power AM service with a very low
barrier to entry.
really should be a way that any school, church, travelers information
service or what-have-you can broadcast for a few miles for not a lot
of money or brain damage, when they want, in such a way that it
doesn’t hurt anyone. The top of the MW/AM band is perfect for that.
One might even split that unused 1700–1800 between the hams and
hyper-band broadcast AM. One might make this unlicensed and lightly
other tweak is making all the big AM guys suppress one sideband.
a 1000 kHz in New York and Los Angeles, but on opposite sidebands so
a good radio here in Denver can select between them. Let every
top-100 metro have one or two 250 kW services, and not a lot else.
Let every state have another one or two boomers.
the sideband technique, we have essentially 200 clear channel
stations, giving every location a dozen or so daytime services and of
course 200 nighttime. Canada and Mexico, which have more MW needy
territory to cover, might play along, considering that a MW radio in
much of the world receives nothing at all as MW services have been
retired. In fact, Canada and Mexico should have more of a share of MW
than the U.S. does in a fair world.
are that this revitalized MW service would result in an interesting
and convenient service that better answers the public interest,
convenience and necessity. Even marginal AM stations move to better
spectral ground too. Even the syndication guys win with FM (or
digital) VHF signals in their markets, backed up by the occasional
wide-area MW simulcast service for the truckers and denizens of the
deserts and north woods. This is a case where we
move from flood plane to hilltop and build nicer places.
mostly, a world of many interference-free diverse voices (all also
available locally on VHF simulcasts) seems a better revitalization of
the MW band than does a cacophony of sizzling digital wideband
signals battling the laws of nature and nighttime propagation in an
attempt to deliver a purely local service into places where MW just
campers, DXers, arm chair travelers, ultra rural residents and owners
of antique furniture-quality AM radios, two dollar transistor radios
and marginal MW stations … all win. That leaves only the
digital-on-MW folks in the cold. Let’s hope they will be happy with
being able to do all-digital on the VHF expansion and migration.
MW return to what it was born to do: a handful of low-fidelity
services with divergent voices to the distant corners of the
continent ... a place for the unique voices of distant lands. MW is
not incurably sick, and extraordinary high-tech resuscitation is not
author is a broadcast engineer active in industry education and
cutting-edge technology, mostly on the streaming and video side. His
first love is AM radio. He says he has four 1,800-foot Beverage
antennas and is “rebuilding a Gates BC-1F like some people rebuild
old Mustang convertibles.”
on this or any story. Email firstname.lastname@example.org with
“Letter to the Editor” in the subject field.