A Simple Way to Increase Radio Reception Range
A
lengthened antenna wire
, that is, adding additional wire to the end of the standard Base-Loaded-Coax antenna,
will usually result in better range. This
random-length antenna
wire will probably not be resonant at the operating
frequency, but this is generally offset by a stronger signal available to the receiver. An improvement will
probably not be seen until the antenna is longer than approximately 10 feet. Lengthening the antenna is a
simple technique for increasing range — for example, a wire may be run up a wall corner and along the
ceiling corner for 10 or 20 feet. Thin bus wire (an uninsulated, silver-color solid wire; e.g.: Radio Shack
#278-1341 is 24 gauge tinned solid wire) almost disappears against a wall when stretched tightly. Simply
drive small nails or brads into the wall corners where the wire will be run, and then wrap a few turns of the
bus wire around each nail head as the wire is stretched into position. Then, strip a small portion of
insulation off the end of the wire on the Vaux-supplied Standard Antenna, and then twist the new bus wire
with it to complete the installation.
Folded Dipole Antenna (Vaux Model ANT-3)
A Folded Dipole Antenna is quite sensitive, and a version of it is often provided with FM receivers (which is,
of course, cut to around 3 feet for the center frequency of the FM band). The Folded Dipole Antenna is
constructed using 300-ohm TV twinlead, which is shorted at each end, and which has one of the conductors
cut at the center. The antenna's impedance at this point is 300 ohms, and a 300-to-75-ohm TV matching
transformer (a 4:1 balun) is connected to provide a 75-ohm impedance for connecting to 75-ohm coax
such as RG-59 or RG-6. Additional twinlead may be inserted between the antenna and the matching
transformer, but it is generally convenient to simply splice the transformer's 300-ohm pigtail directly to the
cut side of the antenna twinlead.
Due to its size, this antenna is best suited to attic installations, where it can be tacked to rafters and
positioned centrally over the home. Best results are obtained using a straight antenna, but it can be bent or
drooped if necessary (with somewhat lowered performance). The coax should exit the antenna at a 90°
angle as much as is practical, and a side or top exit is preferred over a bottom exit to keep the coax out of
the desired reception direction (down in the case of an attic installation).
The Folded Dipole Antenna gives excellent reception (e.g.: 600 feet open-field), is inexpensive and easy to
construct, and uses standard 75-ohm coax installation (cabling, wallplates, etc.). An assembled Folded
Dipole Antenna (the components marked with * below) is available from Vaux (Model ANT-3).
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