Yes. To an extent. The skin depth for W-band waves is very small in aluminum, at most a few mils. Ergo, to the degree that your aluminum foil "sheild" looks like a ground plane, most W-band energy will be reflected. You will experience a problem with diffraction, as waves bend around gaps in the aluminum foil as small as 1mm, leading to a good deal of energy still coupling to your "pain receptacles." Another problem is that aluminum foil is isn't a very good conductor. The surface currents excited by the wave are going to heat up the aluminum very quickly. This problem is exacerbated with small metal objects. Like coins. The wave will couple somewhat to the coin, then pretty much just form current eddys around the coin until the inherent resistivity of the metals heats the coin up until it leaves a nice burn. Then the money will literally be "burning a hole in your pocket."
On the side...aren't LPDA's not especially directional...just fairly wideband? Darnit. Now I'll have to fire up NEC2D and model it. So much for my productivity at work.
A: Yagi antennas are strongly directional. Use the null points in the far-field pattern to reduce the multi-path issue (if this is possible considering the physicalities of the individual situation). B: Use a smaller yagi...I've seen yagi antennas implemented up to W-band(~100GHz). and... C: It was meant to be a joke. I don't expect your average home user to take an antennas course just to figure out how to make an antenna that'll pick up stations they should be able to recieve with set-top bunny-earys. Who in their right mind would put up a VHF yagi-uda antenna in their living room? Not me, my 8-month old son would be using it to pull himself up to stand, and then either bending the antenna elements or de-aiming the thing. No, I'd put it in the attic!
Why not put up a Yagi-Uda in the living room to realy bring in those VHF stations? An 8 foot by 12 foot antenna in the living room makes a great conversation piece, and the kids love it!!
I'd give a similar review to Mepis, though I don't know that I'd use it in an enterprise situation. I recently got rid of Mepis in favor of vanilla Debian sarge (+ the 2.6 kernel), and have had very little trouble with it.
BPL is wrong on so many levels it should die. The FCC hopefully let this theft of the spectrum continue to exist, even in it's present early-testing phase. If a device doesn't comply with the "no harmful interference" regulations, then whoever implements it needs to be seriously fined into compliance.
True, they could choose a carrier frequency that's less obtrusive. The downside is that the power lines (unless I've missed a critical discussion regarding massively altering the power lines themselves) will look more and more like inductors at higher frequencies, thus increasing the T-L's impedance, and screwing with all the matching. It's not that any one particular bend would radiate greatly, but rather that even a small series of them is going to start looking like a much more ominous array of antennas. Perhaps call it a traveling-wave antenna... or a phased-array of small transmitters. Either way, it'll still contribute both background noise and interference around the carrier frequency.
1. Pretty tough to do much data transmission when your carrier frequency is only 60Hz. Though I'm sure that radio astronomers would've been happy to be able to use that VVLF portion of the spectrum. Obviously they can't, as it's massively polluted.
2. To get significant bandwidth over your transmission line, your signal is going to vary by at least +/- the frequency of your signal. Ergo, to get a lot of data on there, they will be emitting a very wide-band signal, possibly...nay... probably interfering with many differently-used portions of the spectrum.
Why? Putting the shield close enough to let the line work well as an RF transmission line is gonna cause some serious issues with most materials that are used as dielectrics. The high voltages (14kV or higher) would rapidly reduce the nominal lifespane of the teflon or whatever dielectric material was chosen. And don't even start with air-spacing the grounding-shield. With the range of conditions out there in the wild... That's sudden-fusing-of-the powerline-to-ground waiting to happen.
I concur, let it die. Even if the power lines are susceptible to EM interference, one must remember that antennas are reciprocal: if they receive well, they'll transmit well. It is really stupid to not consider the possibility of radiation with a transmission-line system anything like our 3-phase power lines. Not only are power-lines poor candidates for RF transmission, but they also have many (as in at every pole) slight bends. Any time you bend your transmission line without very carefully controlling the design, you will have some radiation. With how many millions of power poles there are out there, you can bet that there will be a large increase in the background noise levels for normal RF applications.
Personally, I hate potato salad, as a food, and to some degree as an operating system. It is my least favorite pot-luck dish ever.
And yes, I love those burritos. Makes me hungry. I think I'll leave work early and go home to use Mepis, which sounds rather like a fish burrito, though I don't like fish. Dang. Maybe I'll have a real burrito with some ground beef and an oversized flour tortilla, with lots of cheese and refried beans!
Back on topic...I don't particularly like or dislike Pb & J sandwiches, and if some Pb&J sandwich builder started dissing on burritos, I'd probably say that person was an irrational jerk, and then go to the burrito shop.
I suppose I may be over-literal about the use of the "and" operator, but it doesn't say "or". I may be wrong, and they may mean that any one of those criteria would qualify something to be science, but I think I'll stand by my interpretation...
Sounds alot like what I remember of elementary school "science". Well, the "billions and billions of eons ago" might be a stretch, as it was more like "millions and millions of years ago." In fact, if I recall 9th grade Biology...that's what the teacher said there too!!!(he was the cross-country team's coach as well as the bio teacher...Jorgensen or something like that, but that was back in '94)
Actually, you may be affected by radiation directly below an antenna. While there is a null in the far-field pattern in this direction, you must consider the near-field effects. Assuming a vertical dipole, there is a 1/(R^3) field in that very direction! An example: Verizon recently wanted to put a cell station on top of the engineering building at my campus. The EE department is on the top couple floors, and a professor was very concerned about the 200 kW station that Verizon wanted to install interfering with experiments in the labs which are about 20 feet below where the antennas would be located. The professor had to convince the Verizon people that the far-field pattern did not completely describe the field, especially at such close ranges. In the end, Verizon put a less-powerful cell station on another building on campus (I believe it is where the school's administrators offices are housed).
Softwood lumber?..... You must be Canadian...Alberta? BC? If I recall that seems to be from where we would import softwood (e.g. pine) lumber. Normally, I would be against such protectionist tariffs, but I live in a place which has an economy strongly dependent upon local logging. I also know that the Canadian timber industry is MUCH more well-subsidised by the government than the U.S. timber industry is. Loggers and sawmills in the States have no hope of competing against their subsidised counterparts, especially with the restrictive process required to simply begin to log a section of forest.
Yes, but even traditional light sensors (e.g. a standard visible-senstive photodiode) can be operated in a photovoltaic mode, without the aid of a biasing current. The output voltages aren't very impressive, of course. I don't recall much of Silicon band-gaps and electron mobilities from my materials courses, but it can be done nonetheless.
The "picocells" should be fairly easy to realizse, simply use an array of microstrip patch anennas pointing *relatively* down. Thus, you could have a nice flying repeater for the phones, thereby reducing the transmit power they need to use, and also reducing the noise pollution. The patch antennas would be very easy to realize, as they already use such devices to communicate to satellites for the on-board phones that you have to pay an arm and a leg for.
Slashdot Mirror
"Can aluminum foil reflect a 95 GHz wave?"
Yes. To an extent.
The skin depth for W-band waves is very small in aluminum, at most a few mils. Ergo, to the degree that your aluminum foil "sheild" looks like a ground plane, most W-band energy will be reflected. You will experience a problem with diffraction, as waves bend around gaps in the aluminum foil as small as 1mm, leading to a good deal of energy still coupling to your "pain receptacles."
Another problem is that aluminum foil is isn't a very good conductor. The surface currents excited by the wave are going to heat up the aluminum very quickly. This problem is exacerbated with small metal objects. Like coins. The wave will couple somewhat to the coin, then pretty much just form current eddys around the coin until the inherent resistivity of the metals heats the coin up until it leaves a nice burn. Then the money will literally be "burning a hole in your pocket."
"The uses of this keyboard could prove to be enless."
Well, you could configure the keyboard to be "n"-less if you wanted to...
"Be nice or I'll get my Wouff Hong."
Ok, ok... No need to get violent.
On the side...aren't LPDA's not especially directional...just fairly wideband? Darnit. Now I'll have to fire up NEC2D and model it. So much for my productivity at work.
A: Yagi antennas are strongly directional. Use the null points in the far-field pattern to reduce the multi-path issue (if this is possible considering the physicalities of the individual situation).
B: Use a smaller yagi...I've seen yagi antennas implemented up to W-band(~100GHz).
and...
C: It was meant to be a joke. I don't expect your average home user to take an antennas course just to figure out how to make an antenna that'll pick up stations they should be able to recieve with set-top bunny-earys. Who in their right mind would put up a VHF yagi-uda antenna in their living room? Not me, my 8-month old son would be using it to pull himself up to stand, and then either bending the antenna elements or de-aiming the thing. No, I'd put it in the attic!
Why not put up a Yagi-Uda in the living room to realy bring in those VHF stations?
An 8 foot by 12 foot antenna in the living room makes a great conversation piece, and the kids love it!!
I'd give a similar review to Mepis, though I don't know that I'd use it in an enterprise situation. I recently got rid of Mepis in favor of vanilla Debian sarge (+ the 2.6 kernel), and have had very little trouble with it.
I, for one, found your post quite amusing. It was so wrong that it had to be either sad or funny.
Well thought-out commentary, sir (or madam).
BPL is wrong on so many levels it should die. The FCC hopefully let this theft of the spectrum continue to exist, even in it's present early-testing phase. If a device doesn't comply with the "no harmful interference" regulations, then whoever implements it needs to be seriously fined into compliance.
True, they could choose a carrier frequency that's less obtrusive. The downside is that the power lines (unless I've missed a critical discussion regarding massively altering the power lines themselves) will look more and more like inductors at higher frequencies, thus increasing the T-L's impedance, and screwing with all the matching.
It's not that any one particular bend would radiate greatly, but rather that even a small series of them is going to start looking like a much more ominous array of antennas. Perhaps call it a traveling-wave antenna... or a phased-array of small transmitters. Either way, it'll still contribute both background noise and interference around the carrier frequency.
1. Pretty tough to do much data transmission when your carrier frequency is only 60Hz. Though I'm sure that radio astronomers would've been happy to be able to use that VVLF portion of the spectrum. Obviously they can't, as it's massively polluted.
2. To get significant bandwidth over your transmission line, your signal is going to vary by at least +/- the frequency of your signal. Ergo, to get a lot of data on there, they will be emitting a very wide-band signal, possibly...nay... probably interfering with many differently-used portions of the spectrum.
Why?
Putting the shield close enough to let the line work well as an RF transmission line is gonna cause some serious issues with most materials that are used as dielectrics. The high voltages (14kV or higher) would rapidly reduce the nominal lifespane of the teflon or whatever dielectric material was chosen.
And don't even start with air-spacing the grounding-shield. With the range of conditions out there in the wild... That's sudden-fusing-of-the powerline-to-ground waiting to happen.
I concur, let it die.
Even if the power lines are susceptible to EM interference, one must remember that antennas are reciprocal: if they receive well, they'll transmit well.
It is really stupid to not consider the possibility of radiation with a transmission-line system anything like our 3-phase power lines. Not only are power-lines poor candidates for RF transmission, but they also have many (as in at every pole) slight bends. Any time you bend your transmission line without very carefully controlling the design, you will have some radiation. With how many millions of power poles there are out there, you can bet that there will be a large increase in the background noise levels for normal RF applications.
Thank you...
Excellent commentary on the subject.
Personally, I hate potato salad, as a food, and to some degree as an operating system. It is my least favorite pot-luck dish ever.
And yes, I love those burritos. Makes me hungry. I think I'll leave work early and go home to use Mepis, which sounds rather like a fish burrito, though I don't like fish. Dang. Maybe I'll have a real burrito with some ground beef and an oversized flour tortilla, with lots of cheese and refried beans!
Back on topic...I don't particularly like or dislike Pb & J sandwiches, and if some Pb&J sandwich builder started dissing on burritos, I'd probably say that person was an irrational jerk, and then go to the burrito shop.
Food? Water?
No, no, no...
What about my addiction to AIR??!!
I suppose I may be over-literal about the use of the "and" operator, but it doesn't say "or".
I may be wrong, and they may mean that any one of those criteria would qualify something to be science, but I think I'll stand by my interpretation...
Sounds alot like what I remember of elementary school "science".
Well, the "billions and billions of eons ago" might be a stretch, as it was more like "millions and millions of years ago."
In fact, if I recall 9th grade Biology...that's what the teacher said there too!!!(he was the cross-country team's coach as well as the bio teacher...Jorgensen or something like that, but that was back in '94)
Notice the "and" statement...
If any one of the criteria are not met, then whatever is being discussed is not science:
1*1*1*0*1*1=0
Doomed? Especially those of us who live within 50 miles of it!
Actually, you may be affected by radiation directly below an antenna. While there is a null in the far-field pattern in this direction, you must consider the near-field effects. Assuming a vertical dipole, there is a 1/(R^3) field in that very direction!
An example:
Verizon recently wanted to put a cell station on top of the engineering building at my campus. The EE department is on the top couple floors, and a professor was very concerned about the 200 kW station that Verizon wanted to install interfering with experiments in the labs which are about 20 feet below where the antennas would be located. The professor had to convince the Verizon people that the far-field pattern did not completely describe the field, especially at such close ranges. In the end, Verizon put a less-powerful cell station on another building on campus (I believe it is where the school's administrators offices are housed).
Softwood lumber?..... You must be Canadian...Alberta? BC? If I recall that seems to be from where we would import softwood (e.g. pine) lumber.
Normally, I would be against such protectionist tariffs, but I live in a place which has an economy strongly dependent upon local logging. I also know that the Canadian timber industry is MUCH more well-subsidised by the government than the U.S. timber industry is. Loggers and sawmills in the States have no hope of competing against their subsidised counterparts, especially with the restrictive process required to simply begin to log a section of forest.
Yes, but even traditional light sensors (e.g. a standard visible-senstive photodiode) can be operated in a photovoltaic mode, without the aid of a biasing current. The output voltages aren't very impressive, of course. I don't recall much of Silicon band-gaps and electron mobilities from my materials courses, but it can be done nonetheless.
I didn't read all of the parent's post before replying, thus repeating part of his post!
Even lazier than not reading the article.
Don't forget when you're playing as the batter, they need the feature, "Charge the Mound(with or without your bat in hand)."
The "picocells" should be fairly easy to realizse, simply use an array of microstrip patch anennas pointing *relatively* down. Thus, you could have a nice flying repeater for the phones, thereby reducing the transmit power they need to use, and also reducing the noise pollution.
The patch antennas would be very easy to realize, as they already use such devices to communicate to satellites for the on-board phones that you have to pay an arm and a leg for.
I'm from Montana...
And DUH!! Moscow is in Idaho!
So much for your "good geography skills".