Yes, it's pretty easy to build shortwave antennas. You can make simple ones out of wire (like a dipole or longwire) which work well but aren't very directional. You can move up to more complex antennas and, other than construction details, they're easy to build out of tubing or wire. Of course, making one that works over a wide frequency range is more difficult, and would require a log periodic antenna; with enough space, you could build a log periodic to cover 3-30 MHz without too much trouble.
If not having an antenna is all that's keeping you from shortwave listening, then buy a 100 foot spool of wire from Radio Shack, hook one end up to your receiver, and throw the other end over the nearest tree.
It's equally important, however, to ground the radio. Without a good ground, the radio can't perform up to its potential, no matter how good your antenna system is.
The ARRL (arrl.org) sells a number of excellent books on antenna design and construction.
Computer space vs. outer space
on
Ask Larry Niven
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· Score: 5, Interesting
Mr. Niven, in many of your books, space travel plays a much more prominent role than does the contemporary computer network. The network is usually there, and its presence is implicit in the story, but it's not really important to the story. Here on earth in the present day, the computer network is much more important than space travel, except on the rare occasions when space travel goes wrong. Even space travel seems to be mostly for further propagation of the computer/communications network.
As I was growing up, reading science fiction of all varieties, I had dreams of one day flying in spaceships, living on the moon, etc. It just didn't seem that far away. Now, however, the dream of space seems further and further away -- it feels as though my generation (I'm near the end of Generation X, though I despise the term) has traded the difficult goal of space for the easy goal of computers.
How do you feel about this apparent trend in modern history as compared to the predicted space-based future of many older SF stories? Would you have steered humanity's course differently if you had the chance?
i'd just like to point out that the energy of an electromagnetic emmission does not vary with the type or frequency of emission. a 10 watt FM broadcast radio wave (~100 MHz) carries just as much energy as a 10 watt PCS signal (~1.8 GHz), or a 10 watt light bulb (~700 nm to ~350 nm, or ~400 GHz to ~1000 GHz). as the frequency changes, the signal's ability to interact with your body changes -- your body is resonant at about 100 MHz, and your head is resonant at about 1 GHz.
the fact that cell phones use microwaves to communicate doesn't prevent them from potentially harming you, even at 100 mW. not that they do, but they might. no one knows for sure.
your cell phone would only have to generate about 1 watt to cause gradual damage to your eyes, usually leading to glaucoma and cataracts over a span of years. this could also cause cancer, or have other unpredictable side effects, in your brain. one report even suggested that using a cell phone makes your brain work and respond faster.
gamma and X-rays don't cause mutuations, usually. they cause cancer. (although, if you wanted to argue that cancer was a mutation, i guess i couldn't present a good counter argument.) nuclear radiation only causes superpowers in comic books.
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Yes, it's pretty easy to build shortwave antennas. You can make simple ones out of wire (like a dipole or longwire) which work well but aren't very directional. You can move up to more complex antennas and, other than construction details, they're easy to build out of tubing or wire. Of course, making one that works over a wide frequency range is more difficult, and would require a log periodic antenna; with enough space, you could build a log periodic to cover 3-30 MHz without too much trouble.
If not having an antenna is all that's keeping you from shortwave listening, then buy a 100 foot spool of wire from Radio Shack, hook one end up to your receiver, and throw the other end over the nearest tree.
It's equally important, however, to ground the radio. Without a good ground, the radio can't perform up to its potential, no matter how good your antenna system is.
The ARRL (arrl.org) sells a number of excellent books on antenna design and construction.
Mr. Niven, in many of your books, space travel plays a much more prominent role than does the contemporary computer network. The network is usually there, and its presence is implicit in the story, but it's not really important to the story. Here on earth in the present day, the computer network is much more important than space travel, except on the rare occasions when space travel goes wrong. Even space travel seems to be mostly for further propagation of the computer/communications network.
As I was growing up, reading science fiction of all varieties, I had dreams of one day flying in spaceships, living on the moon, etc. It just didn't seem that far away. Now, however, the dream of space seems further and further away -- it feels as though my generation (I'm near the end of Generation X, though I despise the term) has traded the difficult goal of space for the easy goal of computers.
How do you feel about this apparent trend in modern history as compared to the predicted space-based future of many older SF stories? Would you have steered humanity's course differently if you had the chance?
i'd just like to point out that the energy of an electromagnetic emmission does not vary with the type or frequency of emission. a 10 watt FM broadcast radio wave (~100 MHz) carries just as much energy as a 10 watt PCS signal (~1.8 GHz), or a 10 watt light bulb (~700 nm to ~350 nm, or ~400 GHz to ~1000 GHz). as the frequency changes, the signal's ability to interact with your body changes -- your body is resonant at about 100 MHz, and your head is resonant at about 1 GHz.
the fact that cell phones use microwaves to communicate doesn't prevent them from potentially harming you, even at 100 mW. not that they do, but they might. no one knows for sure.
your cell phone would only have to generate about 1 watt to cause gradual damage to your eyes, usually leading to glaucoma and cataracts over a span of years. this could also cause cancer, or have other unpredictable side effects, in your brain. one report even suggested that using a cell phone makes your brain work and respond faster.
gamma and X-rays don't cause mutuations, usually. they cause cancer. (although, if you wanted to argue that cancer was a mutation, i guess i couldn't present a good counter argument.) nuclear radiation only causes superpowers in comic books.
a good link to check if you're interested in the spectrum: NASA's page on the spectrum.