RF shielding to keep signals inside

[DaveC426913]

I may have blown a hole in my plot I can't sew back up.

I need a way to shield RF emissions to keep them from escaping into the wilderness.
It has to be impractical enough that it can only be implemented on a large scale such as a settlement, not on, say, a vessel.Core premises of the story:

- human colony world about 80 years in
- 22nd century (by Earth reckoning)
- have ftl drive (sigh... to immigrate/emmigrate from/to colony) but that is outside the scope of the story
- have advanced materials such as "smart" skinsuits, strong light alloys, pseudo-molly-wire, chemical processors, etc. that wilderness adventurers make excellent use of.

- ocean world - few large islands but thousands of small islands
- most of population, commerce and industry is concentrated on large island(s)

- indigenous wildlife is sensitive to radio frequencies - can emit and sense in radio range
- first colonists charted world by plane, only to discover that indigenous life would go bananas around RF, attacking and bashing themselves to death
- in a unilateral move, electronics were forbidden everywhere outside high population areas - maybe only until they find a solutionThe rationale for this premise is that this is a man-versus-nature story on the waves and in the sky. If they had GPS, autopilots and island-hopping shuttles, it would be a very dull story indeed.

In first broad strokes, I envisioned
- the dense settlements would have use of electronic devices, industry/commerce machinery (because, otherwise, this colony world is going to be awfully primitive)
- these dense areas would be shielded, so that radio frequencies would not disturb wildlife outside the settlements.

But I am beginning to think that shielding an entire settlement to prevent emission of RF will be quite impractical. I wasn't envisioning them trapped under a Faraday dome!

(I'm aware that, even here on 21st century Earth, FCC regulations require that most small devices have shielding so they don't emit radio noise. I need to explain that away.)

Can you help with some ideas whereby I can have 95% of a world free from electronics, without plunging the populated areas into the stone age?It can't be voluntary on the part of the adventurers. The suspense of the story is driven by the needs of the mission to go into danger while only minimally equipped. Plausibly, if they had the option to override the restrictions, they would do so.

 

[undefined314]

Perhaps the only readily-available materials for sufficient shielding are very brittle and/or dense, making them unsuitable for use on vehicles/tents/portable things. Building and maintaining them might also be so cost-prohibitive that only the well-populated areas are worth the investment.

 

[Rive]

...indigenous life would go bananas around RF, attacking and bashing themselves to death

Well, you know human nerve system also works with electricity (kind of)?

Maybe you can limit the effect to slew rate instead of general 'RF'?

 

[jbriggs444]

How about if you just use the inverse square law? Large islands can afford to have a kilometers-wide exclusion zone on the beaches where electronic equipment is not permitted. Small islands cannot afford such an exclusion zone without reducing the usable "electronics permitted" area to a zero of negligible size.

 

[DaveC426913]

Well, you know human nerve system also works with electricity (kind of)?

Maybe you can limit the effect to slew rate instead of general 'RF'?

Can you elaborate?

 

[DaveC426913]

How about if you just use the inverse square law? Large islands can afford to have a kilometers-wide exclusion zone on the beaches where electronic equipment is not permitted. Small islands cannot afford such an exclusion zone without reducing the usable "electronics permitted" area to a zero of negligible size.

Hm.
I see problems with that:
- the wildlife won't cooperate. Flying critters will be drawn over land and affected.
- even small devices are enough to affect the wildlife. You can't bring a phone for example. I don't think a settlement's radio footprint could drop to effectively zero in any reasonable range.

So the thing is: it's not like radio is mere pollution - it's not like 'polluting the shore is not so bad'. The animals go nuts.

 

[DaveC426913]

Perhaps the only readily-available materials for sufficient shielding are very brittle and/or dense, making them unsuitable for use on vehicles/tents/portable things. Building and maintaining them might also be so cost-prohibitive that only the well-populated areas are worth the investment.

Or, combining it with Rive's idea, maybe devices can have their emissions converted to something harmless, but the add-on machinery to do so is bulky.

So you can have a cellphone, but the RF "catalytic converter" attached to it weighs ten pounds.
It would be nice if the individual devices didn't have to have special electronics to keep them from polluting. It would be nice if there were some sort of cleaning plant that "purified" a zone's RF signals. But that seems a bit of a stretch.

 

[jbriggs444]

I don't think a settlement's radio footprint could drop to effectively zero in any reasonable range.

Such things are not unprecedented. Though the scale may not be as I suggested.

https://en.wikipedia.org/wiki/United_States_National_Radio_Quiet_Zone

 

[BillTre]

Use something like a Harry Potter RF invisibility cloak.
People are now working on visibility cloaking methods that involve bending light around tiny objects.
Extend it to RF wavelengths in your story's future.

 

[crashcat]

A Faraday cage would be expensive to build and probably wouldn't be everywhere, and it makes sense that they would spend the resources on population centers because it gives you the most internal volume per material use, to make large population centers rather than a bunch of small villages.

 

[jasonRF]

Does your world have atmosphere and weather similar to Earth?

If so, and there are phenomena such as lightning, then the wildlife would need to be insensitive to lower frequencies otherwise they would be going nuts near a storm. Or perhaps that is one of the quirks of the planet? Anyway, if there is an ionosphere (and atmosphere + nearby star probably means some sort of ionosphere, although a geomagnetic field can play a large role ...), then the RF from lightning might travel around the planet so the wildlife would usually be in the presence of long-wavelength RF (at least if things are like on Earth). If wildlife is insensitive to it, then humans could radiate long wavelengths safely, in the same way that they can (I presume) radiate at visible frequencies . Implications? Slow electronics. Long-wavelength communication links, which means lots of real-estate for a transmitter if the "threshold" wavelength is large enough. This would, however, allow small vessels to receive, but not transmit over those links.

For shielding - perhaps an active system (same idea as noise-cancelling headphones)? Maybe you just cannot get the required isolation with a small system...

These ideas might create more problems than they solve, but perhaps might spark better ideas ...

edit: in any case, most (if not all) planets would have some sort of natural radiation levels so there might be frequency bands that wildlife is not sensitive to. Or perhaps, perhaps the wildlife evolved sensitivity to it in order to avoid storms / earthquakes / etc., and the rest of the RF frequencies came along for the ride.

jason