your antenna properly
John Doty (firstname.lastname@example.org)
Date: February 11, 1995
Original source: Usenet's rec.radio.shortwave
system is the key to reception at shortwave frequencies.
The antenna itself can be very cheap: $2 worth of hookup wire
can make a great antenna. It's the installation of the wire that
counts. Coax is not magic: it basically works by conducting noise
pickup to ground. It is therefore essential to ground the coaxial
shield well: fanatics will use two ground stakes, one near the
house, one at the base of the antenna, and bury the coax cable
I've experimented with pickup of my computer's 25 MHz clock, and
found that ungrounded coax picks up 36 dB more than grounded coax
in my setup. That's a factor of 4000 in power!
antenna itself away from all kinds of utility lines: power,
CATV, and telephone. Remember that your house is full of this
stuff, so keep the antenna away from your house. An "inverted
L" run up a tree and then over to another tree works very well.
transformer will prevent the "deaf spots" that you may get
at antiresonant frequencies. For an end fed wire antenna, these
occur when it is near a multiple of 1/2 wavelength in length).
Generally, the longer the wire, the less you'll notice these.
If you want
to buy a matching transformer, I like the Model 180 from ICE at
(800) 423-2666 or (317) 545-5412 (no interest, just a satisfied
customer). I've also posted instructions for winding your own;
maybe I should repost.
name antennas will perform well if properly installed, but so
will simple wires. Spend your money on ground stakes.
tuner will improve signal transfer from the antenna to the
receiver, but that's usually useless: modern receivers are so
sensitive that this will rarely make a difference in your signal
to noise ratio. A passive preselector may help with overloading
due to out of band signals. At shortwave frequencies, active preselectors
and preamplifiers only increase your susceptibility to overload
in an otherwise properly functioning system. If a preamplifier
helps, there's almost certainly something wrong with your receiver
or antenna system, and you'll get better results if you fix that.
the advice changes at VHF and microwave frequencies: scanner folks
may well find that careful matching and low noise preamplifiers
are worthwhile. The reason is that the natural noise level declines
with increasing frequency, so greater sensitivity can be useful.)
that the difference in the number of listenable signals between
an indoor antenna and a properly installed outdoor antenna
is often a factor of ten or more. The difference between a $200
receiver and a $1000 receiver is more like a factor of two in
the number of listenable signals, and some find no difference
at all: the extra performance of the fancy receivers costs not
only money, but knowledge and skill as well.