THE
BEGINNER’S GUIDE TO SHORTWAVE LISTENING
Bob Grove, Publisher, Monitoring Times
Planning your Antenna
Any length of wire
will pick up signals, but a well-planned antenna installation will pick them up
better. For shortwave reception, antenna efficiency and impedance matching are
not as important as directivity and noise immunity. That’s because the
"better" the shortwave antenna, the better it picks up both signals
and noise--and there's plenty of noise on shortwave! Directivity favors the signal
direction, while noise immunity rejects the interference.
The maximum signal
pickup comes when the horizontal antenna wire is broadside to the arriving
signal(s); if the desired signals are from the east, the wire should run north
and south. To determine the optimum signal direction for your antenna, acquire
a world globe and stretch a string between you and the signal source. The best
orientation would be when the string (and your wire antenna) are broadside to
the direction of the arriving signal.
Modern, sensitive,
shortwave receivers do not need more than 20-40 feet of antenna, and it can be
think or thin, stranded or solid, insulated or uninsulated. Choose the wire for
strength, flexibility and solderability. Try to get it at least 15-20 feet
above the ground and as far as possible from electrical power lines (NEVER run
it over a power line!); it should also be away from large metallic surfaces
like sheet metal roofing, metalized foil insulation, and aluminum siding.
The simplest antenna
is hard to beat--it's a dipole, a horizontal wire broken at or near the center
by an insulator, and the two sides connected respectively to the center
conductor and a shield of a coaxial cable which runs to your radio. You may
even attach the center conductor of the coax to the near end of an unbroken
wire antenna, ignoring the coax shield; but at the radio, both the center
conductor and the shield (ground) must be connected to the radio for local
electrical interference reduction.
When an outdoor antenna
is impossible to erect, mount it in a high indoor area like an attic crawl
space, although you may have to tolerate electrical interference from household
appliances and computerized equipment. Keep it away from nearby wiring.
Active antennas are simply short elements connected to high-gain amplifiers and, as such, require power, have electronic parts that may fail, are vulnerable to strong signal overload and static burnout, may add noise (“hiss”) to the signal, and are more costly than a wire antenna. The better ones, however, are a good substitute when an adequate passive antenna is not an option.
Tuning In
Spinning the
tuning dial through the frequency range of your receiver is lot like shooting
in the dark; you may hit something, but you never known what it might be! A
good program schedule is essential. Two comprehensive listening guides are
published annually, Passport to World Band Radio and the World Radio TV
Handbook, but for current English language schedules, you need the most authoritative
monthly publication available: Monitoring Times. All three of these
publications are available from Grove Enterprises (toll-free 1-800-438-8155).
Just because a
station is listed doesn't mean you will hear it. factors affecting reception include
signal propagation conditions, changes in the station's schedule,
"beaming" (pattern direction) selected by the station, transmitter
power, distance, interference from other close-frequency signals, and your
receiving antenna and equipment.
Although English
is the official second language for the majority of foreign stations, this
doesn't mean they've chosen it for the time you might be listening. Some
countries use shortwave for outreach to their own nationals.
In general, listening below 10 MHz is best at night, while above 10 MHz is best during daytime.
Megahertz, Kilohertz or Meters?
With modern tuning
accuracy and precision, radio signals are identified by their frequency rather
than wavelength, although broadcasters still refer to the time-worn "meter
band" as a swath of spectrum where they will be heard. The conversion is
simple: to change meters to megahertz (or vice versa), simply divide either
into 300. For example, 75 meters is
equivalent to 4 MHz (300 divided by 75 is 4, and 300 divided by 4 is 75).
To avoid dealing with unwieldy numbers, we choose megahertz (million hertz) or kilohertz (thousand hertz); thus, there are 1000 kilohertz in 1 megahertz, a movement of 3 decimal places. For example, 11,850 kHz is the same as 11.850 MHz. To make it even easier, just replace the comma in kHz with a period to make it MHz, or replace the period in MHz with a comma to make it kHz!
What Time is it?
There are 24 time
zones (meridians) around the earth corresponding to the 24 hours of the day. It
all starts at 0000 Universal Coordinated Time, or UTC (formerly Greenwich Mean
Time, or GMT). When it's
To change your
local time to UTC, simply convert your time to 24 hour time (
Utilities versus Broadcasters
Virtually all
radio transmissions are classified into two groups, broadcasting and utilities.
Broadcasters intend their one-way radio transmissions to be heard by a wide
audience; utilities are everything else, most notably the two-way
communicators.
Broadcasters still
use the venerable amplitude modulation (AM) mode of transmission; nearly all
other signals on the air can be monitored in one of two single-sideband modes,
upper sideband (USB; the majority) or lower sideband (LSB).
Always read the instructions which accompany your equipment and accessories; most complaints are the result of failure to read the instructions.