chuckb@fluke.UUCP (Chuck Bowden) (01/11/84)
phere (much more
during the day then at night).
FM Broadcast is limited to line of sight (actually about 1/3 farther
than line of sight) because it is in the VHF portion of the spectrum,
where in most cases, signals pass right through the ionosphere without
being refracted downward at all.
In the shortwave part of the spectrum, however, signals are refracted
back to earth, even bouncing multiple times. This phenomenon varies
quite a bit with changes in the earth's magnetic field, the amount of
charged particles coming from the sun, and from day to night.
For a shortwave radio (if by major news services you meant BBC, Radio
Moscow, etc.) anything but the very lowest quality "all-band" jobs will
be fine. Since ionospheric conditions the major factor in whether you
will hear a station, and government SW broadcast stations use a lot of
power, most shortwave receivers work fine for this. Sony's very small
SW receivers are good. If you want to cover everything in the SW
spectrum with a top quality receiver and can afford it, an Icom R-70 is
hard to beat.
For getting the baseball games on AM, though, there are some problems.
The MW frequencies are noisy, so a very sensitive receiver will still
get a lot of static. A good antenna is always important, but an ideal
antenna for MW reception would be too big to be practical. One
designed like a TV antenna would probably be bigger than a city block.
The longest wire you can string up will help bring in any distant AM
broadcast stations you can get, though.
Chuck Bowden, KD7LZ
caf@cdi.UUCP (caf) (01/15/84)
Concerning MW listening: A loop antenna with amplifier is often the best bet. Another good alternative is an active antenna (uses a short whip) mounted in the clear, well away from power lines et al., with the mast well grounded. Then again, maybe you are lucky and live where the power lines are clean and the neighbors don't use light dimmers. Then fifty feet of wire strung into a tree will do great! -- Chuck Forsberg WA7KGX CDI Portland OR (503)-646-1599 cdi!caf