Author here, need help "building" a fictional long-range radio transmitter

[Nigel Goodwin]

Hm, that seems a little extreme given that NASA is still communicating with Voyager at a distance of 10 billion miles and Voyager's dish antenna is only 2.7 meters wide. Also, I've just found a web page stating that "Both Voyagers are so far away from Earth that only the largest DSN antennas — 230 feet in diameter — can send commands to the spacecraft. To do that, they use a 20 kilowatt S-Band transmitter. That's about one-half to one-quarter of the power transmitted by an ordinary commercial AM or FM radio station on Earth."

So I still hold out hope that a nuclear generator is unnecessary, though I am starting to think my heroine may need to remotely hijack one or more of the antennas used by NASA's Deep Space Network to get the job done...

AG was somewhat over the top

You already know what is required, high power (particularly for the frequency in use) and a MASSIVE dish - fairly obviously, you could use lower power and a MUCH smaller dish, as long as the other end has a massive dish and high power, and is perfectly aligned at the required time. Perhaps your story could reflect this? - you mention 'hijack' existing equipment, this is probably the most plausible scenario, but has been done numerous times in SciFi stories.

 

[BobW]

would not affect my "willing suspension of disbelief" in the least.

I have to admit that this is the reason why I almost never read science fiction. The so called "science" is usually so lame, that I find it painful to read. However, if the heroine is wearing a skintight outfit, and her breasts are large enough, then no one will be paying attention to the science, and it should be possible to get away with it.

PS, Regarding energy vs. power, in this case power is more important. You could discharge gigajoules of energy very slowly over a long period and never raise the temperatue of a cup of water enough to boil it, or you could discharge it quickly and turn it into plasma. Radio transmitters are rated in terms of power, not energy.

 

[RJAWriter]

BobW, I am REALLY liking your idea, because the hacker angle is exactly what I'm going for. I want my heroine to join a local hackerspace in the course of the story as a necessary step to getting her machine(s) built, and if she can get the other hackerspace members involved in the project ("Hey guys, who wants to build a flux compression generator? It's kind of important, so can you do it by tomorrow?"), so much the better.

I'm also wondering if there'd be any way to combine your idea with, say, the Algonquin Radio Observatory somehow? Because the book's set in Ontario and more Canadian content is always a bonus...

 

[duffy]

Instead of hijacking one big dish, she could surreptitiously commandeer a number of small antennas and make a phased-array transmitter.

Let's say every cell-phone in a twenty-mile radius could somehow transmit a signal such that its carrier was in a perfect phase relationship to an aggregate waveform based on the geographical distance from the center of transmission and the intended angle of the beam. 200,000 cell phones @ 5W each = 1MW.

 

[RJAWriter]

Perhaps clarifying the situation will help spark some more ideas (and thanks to all of you who've responded so far!) --

My heroine, based on Earth, needs to force a small wormhole somewhere in our solar system (exact position and distance of said wormhole is negotiable at this point) to close. The alien machine that generates/sustains this wormhole is on the other side of the hole, so I was thinking the easiest solution would be for my heroine to send a signal through the wormhole to turn that machine off. (Note: She has a friend who's a computer whiz and who is familiar with both Earth and this particular alien technology, who could do the necessary programming for her. He would presumably know the frequency, modulation and data encoding involved. Those details are also negotiable for my purposes; anything that sounds plausible will do.)

But whatever the solution to the overall problem, I would really like it to depend chiefly on my heroine's ability to build a particular machine or a series of smaller machines, rather than on her colleague's amazing programming skills or what-have-you. So while buying, borrowing or hijacking existing equipment could be a viable part of the solution, I'd greatly prefer that it not be the whole solution. I really want my heroine to Make Something, whatever that Something turns out to be.

So that's why I thought perhaps her constructing a radio transmitter would be useful, but I'm certainly open to other ideas (like BobW's) if they fit the bill better.

 

[duffy]

Here's a picture of one of the most powerful amateur "moonbounce" antennas built so far -



It consists of log-periodic dipole elements, is directional, handles high power, is well known for being able to bounce signals off the moon, and something a motivated science chick could build.

Here's a couple of pages with great pix of high-power finals, to give an idea what might be involved -
**broken link removed**
http://www.nd2x.net/N2UO.html
http://www.cqdx.ru/ham/new-equipment/qro-tsunami-rf-linear-amplifier/

Those are in the 2 - 10 meter range.

Or she might go with a higher frequency and use an array of surplus satellite dish antennas...



...build her own solid-state final amplifier...



...use a microwave signal generator for the exciter, and frequency stabilize it with an atomic clock - both of which can be acquired from eBay relatively cheap.

 

[unclejed613]

.... or she could go the opposite route, and use ELF.... for instance the "hacking" part of it could be toggling many phase balancers on the power grid simultaneously to create a 60hz PSK signal radiated from the whole north american power grid.... or something like that...

 

[Brevor]

Perhaps your heroine could tap into HAARP, It actually exists. And already has lots of controversy.

https://www.youtube.com/watch?v=MnRPZOUVhJ4

 

[duffy]

He said he wants her to build something - give her something to build and quit hacking into everything!

At the most basic level, Space Bunny 2000 (the protagonist's official name because OP hasn't provided one) is going to need:
1. Frequency source
2. RF amplifier
3. Directional antenna
4. Power supply

But she also needs a few key pieces of information before she's going to bother to plug in her soldering iron:
1. Frequency the receiver is tuned to
2. Sensitivity of the receiver
3. Location of the receiver
4. Duration of transmission

What's the alien receiver like? If they have the technology to manipulate wormholes, good chance they aren't detecting RF with transistors and diodes. Maybe they use a ring of superconducting material and look for quantum interference effects, the so-called "SQUID" device. This has been shown to be much more sensitive than ordinary radio receivers.

In this case, a crummy little 500W rig isn't unreasonable to get to a location just this side of Neptune (2bn miles). It would take about 3 hours.

What's the duration of the transmission? Unless this is a very brief burst, she's going to need her antenna to track the object to compensate for the rotation of the Earth. So, at least one motor and gearbox on an equatorial mount.

 

[RJAWriter]

Duffy, you are my hero (wow, that was a girly thing to say, but well, guilty as charged). This is exactly the kind of information I'm looking for and am capable of understanding at my level of non-expertise, as well as good questions for me to think about.

Love the idea of the SQUID as well, as a ring of superconducting material capable of detecting quantum interference would fit perfectly with my wheel-shaped alien space station. And "Space Bunny 2000" cracked me up -- though for the record, her name is Niki, which is much shorter to type!

So perhaps Niki's job could be to build or cobble together Parts 1, 2 and 4 to the necessary specifications (provided by her Clever Alien Programmer Friend)? And as for the antenna, perhaps she could hijack that Algonquin Radio Telescope I linked to before, since it's not that far away? (Note: There are some great pictures of the exterior and interior before its recent restoration on this page.) A five-hour road trip for Niki and her friends would not be a bad thing at all in the context of the plot, so might it be possible to use the ART as the directional antenna if my characters sneaked through the bush at an appropriate time of day/night and set up their homemade rig close by? Or would using an existing telescope negate the need for any kind of homemade equipment?

As for the answers to those questions about frequency, sensitivity, location and duration, they can be whatever I need them to be, so any plausible values will do. Though duration, I would think, would be a very brief burst, since it's a simple "OFF" command. (Unless I am greatly underestimating the complexity of telling a device to turn itself off, which is entirely possible. See: Not An Expert, Me.)

Thanks again to all of you for giving me so many great ideas and food for thought.

 

[duffy]

Glad to see you're writing "hard" sci-fi, this is far and away my favorite kind. Matter of fact, I question whether the rest is really even science fiction at all. Soft sci-fi just seems to be fantasy with a style treatment.

I searched through the pages on Algonquin, it does not have a transmitter listed, just receivers. So Niki would still need to build a transmitter and connect it somehow.

The text mentions that it has both a prime focus and Gregorian focus. This says the feed is sometimes in the "Focus Cabin" on the end of the arms in front. The Focus Cabin also contains a smaller dish reflector, and sometimes they will use that to reflect the signal to the "Vertex Room", located just behind the main dish and just in front of the "alt bearing" pivot.

 

[RJAWriter]

Duffy, I'm not sure anything with wormholes in it can really be considered hard SF, as the whole area of wormhole theory is pretty much pure speculation, and once you start talking about "exotic matter" with "negative mass" you might as well get out your magic wand. However, I do want to write something that doesn't flagrantly contradict known science if I can help it!

I'm totally fine with Algonquin not having a transmitter, as this would explain why Niki has to build hers. If they need a big antenna, and the Algonquin is the biggest radio telescope within driving distance, it makes sense. All I need to figure out now is a plausible way for them to "hijack" the antenna for the purposes of transmitting their signal. Then they could use the receivers, perhaps, to confirm whether that signal went through properly?

I've finally made up my mind about where the wormhole is, as well. Definitely further than the 2 million miles I mistyped the first time, but a lot closer than the 2 billion I originally proposed -- I'm putting it just inside the closest (to Earth) point of Mars' orbit, 35 million miles out. Since the receiver on the alien space station is so sensitive and they can aim the antenna directly at the wormhole, a 500 watt rig should still be enough, yes? (I hope?)

 

[unclejed613]

if i had myself a machine that could create a stable wormhole, and had used it to open one, i might not be inclined to make it simple to turn off. i might have a complex "key" to turn it off, most likely the sequence would be heavily encrypted. maybe several layers of encryption. i have seen one sci-fi series where an alien race had left a 9-dimensional puzzle for humanity to solve , and that puzzle was the key to both race's survival. if, on the other hand, the thing were dangerous in the event it became unstable, i might also want a "panic button" to shut it down quickly in an emergency. i gather your heroine is trying to hit the "panic button" on the thing... maybe there's a hidden danger in hitting the panic button, that the normal shutdown process avoids...

 

[duffy]

the whole area of wormhole theory is pretty much pure speculation

Wormhole = Einstein-Rosen bridge. Einstein = street cred.

use the receivers, perhaps, to confirm whether that signal went through properly?
a 500 watt rig should still be enough, yes? (I hope?)

Algonquin is designed to receive signals in the 1 - 12 GHz range. Voyager's 11 billion miles away and it transmits to Earth with only 18 watts, so 500 watts is, you know, 27.7x stronger. The sensitivity of the receiver and the noise environment make a huge difference, outer space is normally very quiet on the frequencies space probes communicate on. I have no idea what the noise environment of a wormhole would be, don't think anybody does.

 

[RJAWriter]

As a final addendum to this thread, I thought I should mention that the book I was researching has now been published in the US: Quicksilver by R.J. Anderson (Carolrhoda Lab/Lerner Books, January 2013). I have gratefully mentioned those forum members who were kind enough to answer my questions, correct my errors, and make such great suggestions in the book's Acknowledgments. Thanks again to you all.

 

[cowboybob]

Can't wait to get a copy!!

 

[ronv]

$10.50 for a kindle version.