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Antenna Arrays Could Replace Satellite TV Dishes
Zothecula writes "There was a time not so very long ago when people who wanted satellite TV or radio required dishes several feet across. Those have since been replaced by today's compact dishes, but now it looks like even those might be on the road to obsolescence. A recent PhD graduate from The Netherlands' University of Twente has designed a microchip that allows for a grid array of almost-flat antennae to receive satellite signals."
Surely the small parabolic dish is more compact/efficient than an antenna array? I looked at the article but it doesn't show any pictures of what these new antennas would look like.
It would be cool if something like this could be used to replace the big, bulky antennas needed for Broadcast TV and Radio.
"I disapprove of what you say, but I will defend to the death your right to say it." - historian Evelyn Beatrice Hall
so now I can have an array of small (?) flat antenna instead of one medium sized one? Is that better? I'm sure there's some cool scientific breakthrough here, but the article left me wondering what it is.
So, I'm no expert on signal analysis, but I understand the whole concept of Satellite Dish arrays and why we have those big fields of Giant Dishes pointed at the stars to read incoming data.
This article doesn't seem to point out any of the information that might be handy. How far apart do your antenna's need to be, how big exactly do they need to be, how many, all that good stuff.
For all I know, it might need a hundred of centimeter long antenna's spread across the entire length of my yard. Would THAT make a dish obsolete?
Marcel van de Burgwal's system would not need to be aimed. Instead, the antenna array would electronically "aim" itself. It is a concept similar to the LOFAR project, in which numerous antennas located across the northeast Dutch countryside are linked together to form a virtual radiotelescopy dish. LOFAR requires a lot of calculations and fast communications, as would van de Burgwal's system - that's where the chip comes in.
Instead of the usual elaborate, energy-hungry processors, his system contains multiple smaller, simpler processors on a single chip. They can carry out tasks more flexibly, and can be turned off when not in use. The system's infrastructure operates as a miniature network, in which TV or radio receivers are defined by software, as opposed to the traditional coils and crystals. The approach allows an entire computer network to be constructed over a space of just a few millimeters.
"Software-defined radio may seem much more complex, but we can pack so much computing power into the space taken up by, for example, a coil that it more than repays the effort", he stated.
Van de Burgwal also discovered that his multi-processor chip would work well for digital radio reception on smartphones, due to its low energy use. The technology is being further developed by U Twente spin-off company Recore Systems.
It must have been something you assimilated. . . .
This does appear to be a solution in search of a problem. Today's dishes are already tiny enough to easily mount on an RV. Although, someone needs to tell Allstate insurance, because their commercial seems to indicate they believe a 25 pound dish can obliterate a carport.
Gamingmuseum.com: Give your 3D accelerator a rest.
if you connect it with Monster cables.
Eloi are stupid, throw morlocks at them!
Raw size does matter here. A larger receptor is better.
Which explains why the small dishes now do similar things that the old big ones did?
I suspect it *is* the software that can filter out/account for that interference on a slightly less quality signal that makes the smaller dishes do just fine.
Bigger is better at the extreme end of a broadcast range; i.e. listening for something from outside the solar system or something incredibly weak compared to background noise.
I would also bet that the satellites being used now are more powerful than the original communications sats. So higher signal means, smaller dishes are workable.
If a flat antenna can pickup the signal, I'm sure it will be a bit different than a parabolic concentrating dish. That's exactly was software is made to do. (aren't most internal cell phone antennas these days flat by design? thought I something a while back on fractals in antenna design towards that effect)
People in cars cause accidents....accidents in cars cause people
There are a lot of phased array sat antennas on the market, e.g. http://www.raysat.com/ - TFS makes it sounds like a new idea.
Phased-array antennas really do work but they are not new. The nice thing about them is that they have electronic steering, so they can steer really fast while a conventional antenna of equivalent size would take much more time to move.
The problem with articles like this (and their Slashdot introductions) is that they always come off as student makes big scientific break-through rather than student applies well-known science.
Bruce Perens.
The real news is the last paragraph of the article:
"Van de Burgwal also discovered that his multi-processor chip would work well for digital radio reception on smartphones, due to its low energy use. The technology is being further developed by U Twente spin-off company Recore Systems."
There is more money to be had from a general purpose antenna receiver in smartphones. At the very minimum, faster ROI which is what will drive the faster development/implementation into the consumer market.
What the article doesn't say is just as interesting. I'd be more interested in signal loss ratios and other engineering things. Maybe the dishes are better at what they do than what this chip can do. Still, it's nice to see promising research like this that will drive further research projects.
and how well does this work with rain fade?
When they can eliminate LOS requirements, THEN they have a breakthrough. Also, Sirius Satellite Radio has an antenna about the size of a half dollar. It works anywhere there's no obstruction of the general sky. Why do TV antenna's need to be so much bigger and point "dead on" at a very precise location of the sky. Also fix rain fade and we've got a winning product.
Substantially the same story has been popping up regularly for about twenty years. It's like the flying car story. It's always just around the corner, but it never reaches the market, at least not at a competitive price.
Those who would give up essential liberty to purchase a little temporary safety, deserve neither liberty nor safety.
does it snow a lot where you live ? If it does, can you please tell me the model of your small dish ?
Jehovah be praised, Oracle was not selected
Raw size does matter here.
A larger receptor is better.
Which explains why the small dishes now do similar things that the old big ones did?
Or it could have something to do with the wavelength of the radio signal being received. Longer wavelengths require larger receivers. For an example compare your eyes (wavelengths measured in angstroms) with a radio telescope (wavelength measured in meters). (of course, power and efficiency also enter into it, but the bigger factor at play is the wavelength)
The observatory consists of 27 independent antennas, each of which has a dish diameter of 25 meters (82 feet) and weighs 209 metric tons (230 Short tons).
http://en.wikipedia.org/wiki/Very_Large_Array.
The flat surface to dish per the original article is a trick where you vary the electrical distances of each of the patches on the flat surface to shift the signals as though they were spatially received by a dish shaped surface. You can apply the same trick to dish antennas which have much better directional gain than flat patches and do a super gain antenna.
A collection of links on antenna arrays at a ham radio antenna design site: http://www.dxzone.com/catalog/Antennas/Array/
It's not all about signal strength. Sensitivity these days is rarely an issue; the electronics in the receiver are excellent. Of greater relevance are polarization, rejection of off-axis noise, directivity, and the ability to reject signals from adjacent bands. There are also issues of setup difficulty, and this is what the primary focus of the design in question is.
Aiming a dish antenna is a chore, and high winds which shake a parabolic dish can cause signal strength to fluctuate dramatically. An electronically controlled phased array can, by introducing delays to various antenna elements, "steer" itself and lock onto a satellite with great accuracy (within a few degrees of the direction the array is aimed). A small antenna, perfectly aimed, will outperform a larger antenna poorly aimed, and if the antenna's controller can aim itself without physical adjustments many thousands of times per second, wind and a... coarse job of aiming the antenna are non-factors.
A military example: PAVE-PAWS, a 435Mhz missile detection array used by the US Air Force. The antennas in question are made of thousands of smaller elements (a single dipole element at 435MHz is about 35cm long), do not move, but the transmitted radar beam and the reception-aiming can be extremely precise. The more elements you have, the narrower the beam but the higher the gain.
L-band, commonly used by companies like satellite TV providers, is 1 to 2 GHz. An array of 16 log-periodic (wideband) antenna elements would therefore be 60cm square. A 4-element array would be 30cm square. Pretty compact, and if it gets rid of the most common cause of poor signal strength (a poorly-aimed dish), it's a win.
Everybody gets what the majority deserves.
What's new isn't a phased array antenna for satellite TV, you can get them now, though they might cost several thousand dollars vs less than $100 for the small dish.
The Gizmag article mentions the new chip being cheaper and lower power as opposed to what is currently used. Besides being "flat" and sticking out a phased array satellite TV antenna would be easier to install as it could be aimed electronically rather than physically pointing the antenna. It would still need to be pointed in the general direction, but would require less fiddling with.
802.11n directionality is achieved by phase summing the signals from 2 or more dipoles.
Yawn.
Oh yeah the patent for 2 or more phase locked receivers on one chips is pretty old. So even getting it onto one chip is not new.
http://www.freepatentsonline.com/7636554.html
A MIMO radio transceiver to support processing of multiple signals for simultaneous transmission via corresponding ones of a plurality of antennas and to support receive processing of multiple signals detected by corresponding ones of the plurality of antennas. The radio transceiver provides, on a single semiconductor integrated circuit, a receiver circuit or path for each of a plurality of antennas and a transmit circuit or path for each of the plurality of antennas. Each receiver circuit downconverts the RF signal detected by its associated antenna to a baseband signal. Similarly, each transmit path upconverts a baseband signal to be transmitted by an assigned antenna.
Granted, they are not phased array so you need to aim them, but flat Ku band satellite antennas have been around for over a decade around here. Here is a random example a quick googling turned up: http://www.techradar.com/reviews/audio-visual/digital-tv-receivers/sqish-selfsat-h10d-420191/review
/greger
This isn't new, BSB here in the UK had a flat satellite receiver which they called the "Squarial". It was a phased array, like other people have said.
Now, if it could be electronically adjusted to pick up different satellites without having to physically move it, that would be interesting. I believe some military radars do this.
No. The LNB has gotten better, the 'antenna' that a dish uses, they used to be 1.2 dB, and 0.9 dB if you wanted something expensive. todays standard is 0.3 dB, so you have enough with about a quarter of the original signal.
My not so expensive 6 year old dish system still receives the same signal strenght.
Phased arrays for DirecTV reception have been on the market for at least a few years. Here's one:
http://www.solidsignal.com/pview.asp?mc=06&p=KVHA7&d=KVH-TracVision-A7-InMotion-SUVMiniVan-DIRECTV-Satellite-TV-Antenna-System-(A7)&c=Satellite%20Dishes%20for%20SUVs&sku=
Supposedly the student has developed a signal processor that will reduce power consumption and/or cost, but the article is REALLY slim on details as to how they did this and whether they really have made any significant breakthroughs beyond what's already there.
retrorocket.o not found, launch anyway?
Have the wavelengths of the sat broadcasts changed? This about using a new type of antenna to handle an existing broadcast, not trying to receive a different signal, no?
I suppose the old sats might use a different wavelength than say DirecTV sats I guess.
People in cars cause accidents....accidents in cars cause people
Forget about snow. A friend used to lose his TV signal about 45 minutes before it rained.
Lost at C:>. Found at C.
GP is correct - the dish size has all to do with the gain of the antenna, not the resonant frequency. The actual antenna is at the focal point of the dish and it's length IS frequency-critical. The surface area of the dish directly corresponds to its gain.
The reason we no longer use giant 6' dishes is twofold - because they are using 24 GHz instead of 5 GHz means the antenna at the focal point is much smaller, and the area of the dish is relatively the same size - with relationship to the wavelength - which is also much smaller.
The other reason is the peak power of, say the DirecTV sats, is as high as 150W for some transponders, whereas the older C-Band stuff was about 10W peak.
Dishes typically are designed to produce somewhere around 30dB of gain, which is 1000x magnification of the signal over a straight dipole with no reflector.
-- You are in a maze of little, twisty passages, all different... --
The amount of spectrum bandwidth required to transmit a few hundred audio channels is a fraction of what is needed to transmit a few hundred TV channels.
So given a constant amount of power available, the power spectral density when transmitting audio only is significantly higher than when transmitting television.
Also, Sirius uses satellites in Tundra or Molniya orbits (I don't remember which), which are geosynchronous, but not geostationary.
retrorocket.o not found, launch anyway?
Raw size does matter here. A larger receptor is better.
If you RTFA (yes I know it is Slashdot but hope springs eternal) you'll see that the system uses a GRID of flat antenna which it combines to simulate a larger antenna. By altering how the signals are combined i.e. the delays between them you can "point" the antenna at different sources. Hence you not only have a large detector from combining several smaller one but you can also point the thing without having to mechanically move it. It's brilliant idea and one that radio astronomers have been using for quite a while.
Your attribution of this effect is wrong.
The old 2m-3m satellite dishes were for receiving analogue signals. By going digital, it is far easier to detect and sufficiently correct for using a very weak signal. That gets the dish size down to about 1m. The other 50cm difference in size is due to the newer satellites using a higher power output.
www.wavefront-av.com
Yes, and no.
The old satellites did use a longer wavelength, it is true. In both cases, however, the parabolic reflector in use is several orders of magnitude larger than any dimensions dictated by the wavelength. The only tuned element (which is where wavelength comes into play) is found at the narrow end of the feedhorn, up in the LNB.
The new ones are smaller because digital signalling has replaced analogue, in turn making error correction possible and sufficient for 99% of the time, and by the fact that the newer satellites put out a more powerful signal.
www.wavefront-av.com
Yes, size matters, but an array of small antennas can have the same effective size (or larger) than one large parabolic dish and still take up less physical volume (it could lie flat against your roof). The bigger advantage is that such arrays can be steered electronically so you don't need to do fine mechanical adjustments to a dish to aim at the satellite and can even aim at a different satellite without any mechanical gears or motors.
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It's the difference between C band and Ku band. C band is 5.850–6.425Ghz while the Ku Band is 12 to 18 GHz. you need a LOT LARGER dish for C band to get the same gain that a small dish at Ku band will get. THIS is the reason why today's home TV dishes are smaller. NOT technology or power. In fact a Lot of TV is still available on the C band. I have friends that have a couple of the big dishes and get a lot of channels, two pay for HBO and STARZ and get about 40 channels of them in the pack for about $100.00 a year.
The biggest advantages have been in low noise temperature Amplifiers and block converters.
With a small 36-38" dish and a premium LNB I can pull in DishTV through a tree during a massive rainstorm. My FTA setup regularly pulls in the europe birds through the neighbors trees with it's 120cm dish and it's invacom 0.3db quad LNB. The garbage grade 28" dish and trash grade LNB they give you when you get your "free install" can barely pull a good signal through a cloud.
Do not look at laser with remaining good eye.
cheap weather radar
- just to name a few applications beside simple satellite reception.
- It is not a ground breaking technology - but also computers were known before the PC came!
Have the wavelengths of the sat broadcasts changed?This about using a new type of antenna to handle an existing broadcast, not trying to receive a different signal, no? I suppose the old sats might use a different wavelength than say DirecTV sats I guess.
Yes, the old C-band has a much greater wavelength than the present Ku-band.
"The likes of Facebook and WhatsApp are free to those whose privacy is of zero value."
there really hasn't been anything worth while on TV (dish, ota, cable, ip, you name it.) ...
GP and YOU are mildly incorrect. WaveLength of the signal is impotant to the gain of the dish. a 5ghz signal has less gain on a 5 foot dish than a 20ghz signal does.
a 3 meter dish at 5 ghz has 21.704db of gain.
the same dish at 20 ghz has 54.415db of gain....
massively more gain on the same size of dish simply because of the frequency of the signal.
you also ignore that the LNA's used today are 20 times better than the ones from only 5 year ago.
But during heavy showers you'll need more amplification than under a clear sky.
How you achieve the amplification, larger dish or better electronics, is fairly immaterial for the end result.
"The likes of Facebook and WhatsApp are free to those whose privacy is of zero value."
Any directional antenna needs to be aimed. Bump it an you loose the signal. with a phased array, you can combine the signals from each 'antenna-let' to act like a dish as far as signal strength is concerned. If you want to connect to multiple satellites, you don't need to move anything, you just have the signal processor combine the signals with different phases to lock into a different direction.
Think global, act loco
The article states that this work is being done by a recent graduate in a PhD program. That doesn't make him a student. A young Ph.D. has developed a low power controller for a phased array radio receiver. This is a nice piece of kit with a range of applications in mobile devices. It builds upon technologies that have in the past been dominated by defense contractors. Our young Ph.D. is helping to make this technology more accessible to the 99% of the world who are not spooks. This is all good, even if it is not groundbreaking.
Think global, act loco
Sirius Satellites Radiosat 1 through Radiosat 3 fly in geosynchronous highly elliptical orbit (Tundra orbit) in a 24-hour orbital period. The elliptical path of its satellite constellation ensures that each satellite spends about 16 hours a day over the continental United States, with at least one satellite over the country at all times. The orbit allows the satellites to broadcast from directly overhead the continental United States, avoiding the problem of large buildings or objects blocking the signal and requiring a much smaller terrestrial repeater network than does sister network XM.
They are also not higher power, they are transmitting a lot less bandwith than a TV bird is. lower data amount = lower power needed.
Finally their orbit makes them a lot closer to the earth than a geostationary orbit... giving them a simple boost from less distance and the advantages of the inverse square law.
Do not look at laser with remaining good eye.
Oh wait, I have one in my pocket.
Think global, act loco
ok thanks for the insight that: "How you achieve the amplification, larger dish or better electronics, is fairly immaterial for the end result."
Jehovah be praised, Oracle was not selected
How long ago was that? Up until I got U-Verse I had been a Dish customer and I never lost signal even during hurricane Ike (I live in Houston). Well at least I didn't until the power went out. My next door neighbor lost her comcast cable about an hour after the storm hit and it was out for six weeks.
"A person is smart. People are dumb, panicky dangerous animals and you know it." - K
After 2000, before 2004 for that particular person. I've seen the same on other dishes more recently, but I don't see it very often (satellite that is).
May be our latitude (I'm a fair bit North of you) and because our dishes are only tilted up about 15-20 degrees ... who knows. But, I've definitely seen it on numerous occasions, and still occasionally see it in bars when they have satellite TV.
Lost at C:>. Found at C.
This is not new or even especially clever compared to some antenna designs. And it does actually work and has benefits.
Aegis cruisers use a phased-array radar set that solves a multitude of problems - flat panel does not need to be physically articulated or rotated, it 'aims' virtually instananeously, allowing the system to track multiple targets with high precision, and I bet it consumes substantially less power than a moving dish or other types of antennae.
Replacing various reflectors with an array, one managed by a dedicated logic device, sounds like a very cleaver solution. Among the advantages:
- Flat-panel mounting on the side of your building. Neighbors might like the look better.
- Simplified aiming. Let the chip make the adjustments. Might even get an aiming aid built into the array some day, making ti a lot simpler than it has been.
- Possibly, just maybe, this would be a dual-purpose antenna, supporting satellite video and neighborhood WiFi or the equivalent. That's a play some ISPs might be interested in. Probably not your cable company.
The most obvious disadvantages to me are potentially fragile electronics and longevity, same coin different sides.
But this stuff does work.
Now to get it micro-sized to fit into a phone.
deleting the extra space after periods so i can stay relevant, yeah.
"The actual antenna is at the focal point of the dish and it's length IS frequency-critical."
The dish is a simple parabola, it's focal point is not frequency dependent. Its gain IS frequency dependent however. Achieving the same gain at half the frequency requires double the dish size (or, double the frequency and you can halve the dish size for the same gain).
As long as the dish is smooth enough its focal point is not frequency dependent. At the extreme low end things fall apart (i.e. the dish becomes on the order of a wavelength in size).
Satellite dishes are smaller now because the original C band transponders were power limited compared to the current Ku band transponders. As well, antenna size is related to wavelength so equivalent antenna designs for a high frequency (Ku band) will be proportionately smaller than for a low frequency (C band).
So... sat-TV receiving dishes are smaller because both the satellite transmit power and frequency increased.
Digital Signal Processors (DSPs) can do a lot, but all receiver processing (analog or digital) depends on getting an analog signal from the antenna that has sufficient S/N and power. Think GIGO. It is the same with radio signals. With sat-TV DSPs are not the reason for the change to smaller antennas. It is almost entirely due to the change to higher power Ku-band transponders.
Various array antennas have been around for a long time. TFA doesn't give much detail and isn't even clear about what is being proposed but there is a better description here:
http://wwwhome.cs.utwente.nl/~burgwal/research.php
What is interesting about Burgwal's chip is that it could make a mass-produced array practical for a lot of purposes, including sat-TV receivers. That may not be the killer app for the chip tho since the dishes are cheap, efficient, and easy to set up.
Although, it would be nice to just stick a flat antenna device on a wall without any set up. A lot of installers would be out of work!
The change in size was due to a move to Digital, NOT just an improvement in reception technology.
"Draco dormiens nunquam titillandus."
Being susceptible to interference does not mean that a minimum size is required or has been reached for the detector.
You could just as easily and with as much validity use the same argument on the old style large satellite dishes. However for most consumers' needs the new smaller ones work just as well, are easier to deploy and cheaper.
These new arrays when they come to market will probably be just as good for the average consumer, smaller and thus easier to deploy.
I'm already getting sat radio through a device that could almost be hand-held for my car. Video signal is just more throughput.
1) Your first paragraph was jacked from wikipedia.
2) Sure it takes more power to transmit over a larger frequency, but if you have a device transmitting across 10Mhz @ 1 watt, it will take more power than a device transmitting across 20Mhz@1mW. Just because you are transmitting a large amount of data (or small) doesn't mean you can't have high power.
3) When the Sirius satellites are actually transmitting, they are actually FURTHER out than a geostationary orbit. It's actually kind of neat. They are pretty far out when they are "hovering" over Saskatchewan which causes their relative movement to slow (the earth actually rotates faster for a bit creating a 'loop' in the orbit), and allows them to spend more time over North America. As they head south, they get closer to the Earth so that they can quickly fly over South America and get back up North and start transmitting again. This is what creates the 16 hours a day over our head. If the satellite was at a constant height, acheiving 16 hours would be impossible.
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I don't believe that DSP implementation in receivers was responsible for smaller antennas. If you have some references you can point me at I would appreciate it.
In a 40 Mbs tv digital stream there is about 17 Mbs of forward error correction. This allows the base fairweather signal to still be usable when rain/snow deteriorates the reception. This means that instead of losing your reception when it rains, you can still watch Jersey Shore (or Big Bang).
DSP implemented communication sets usually don't have any better sensitivity specs than analog units but they do have a lot more flexibility and functionality. For example: an NRD 545 receiver is almost all DSP and is very sensitive (.32uv for 10db) but an analog Drake receiver is better at 0.25uv. I kno this is an analog audio modulation and not digital video but very basically it is about pulling a usable signal out of the noise.
However, the NRD has an incredible set of features for dealing with the signal, including notch filters and continuously variable bandwidth.
Basically, though, what comes out of the analog front-end is what is important and what determines whether or not a signal is useful. The error correction allows signal deterioration due to weather or other conditions to not affect reception until things get really bad.
Raw size does matter here.
That's what she said.
Where is the "Ignorant" mod tag?
Antenna performance (in this case a parabolic dish) depends on several factors. The old C-Band dishes needed to be 10 feet across due to relatively low power on the downlink, and because the gain of a dish depends on its size relative to the wavelength of the signal. C-Band used a 4.7 Ghz signal, which has a wavelength of about 6.3 cm, or about an 2.5 inches. Later dishes received Ku band signals, where were about 11 Ghz, which have a wavelength of 2.7cm, or a little bit more than an inch. Proportionately, a 4 foot Ku band dish has about the same theoretical gain as a 10 C-Band dish. The newer satellites are also more powerful, and preamp performance is improved as well, which is why a 2 foot "hubcap" dish can pretty much do the same thing as the old 10 foot C-band dishes.
Too much gain can have drawbacks as well. If you can aim one of the old 10 foot dishes adequately, you will get EXCELLENT performance on Ku band, but with increased gain comes a narrower beamwidth, which makes the dish harder to aim at the desired satellite. The smaller dishes are a much more rugged, stable, and less expensive platform than the 10 footers of old, which needed massive foundations and supports to maintain stability, particularly in high winds.
You probably caught the Nova Episode about fractals, it has a segment where it talks about fractal phone antennas:
http://www.hulu.com/watch/181084/nova-hunting-the-hidden-dimension
Here's some other stuff:
http://en.wikipedia.org/wiki/Fractal_antenna
http://classes.yale.edu/fractals/Panorama/ManuFractals/FractalAntennas/FractalAntennas.html
http://www.fractenna.com/
loose: not fitting closely or tightly != lose: to suffer the deprivation of
dB is log, so that's not really right.
for example (I don't know which units sat uses, but it isn't really relevant except in absolute terms)
0,3dBm = 1.07mW
1,2dBm = 1.32mW
It's a slight improvement, not 4 fold.
Sent from my PDP-11
>The change in size was due to a move to Digital, NOT just an improvement in reception technology.
Ummm ... yes and no. If you listen to talk radio, virtually all of those voices (whether conservative or liberal) have two things in common: (1) they're distributed digitally (typically with some variant of MPEG or AAC, for the curious. and with VERY robust error correction) and virtually all of them are delivered via C-band satellite. Rush, Phil Hendrie, Laura Ingraham, you name it. We have both a 3 meter and a 3.2 meter dish at our radio stations. The satellite providers recommend these dish sizes, even with digital signals.
As others here have pointed out, the higher the frequency, the smaller the dish can be for the same gain. You could use a humongous dish for Ku Band, but it would be a waste, especially with a digital signal. (That's where you're partially correct, which is why I said, "yes and no.")
However, also in fairness to you, there's beamwidth (i.e., the ability to reject other satellites to either side of the one you want). That's one big reason why we still have to use the giant, honkin', hateful, heavy and HUGE 3 meter dishes. The C band is a nightmare and has been for years.
By the way, on the original subject ... phased/grid arrays have been around for decades. The fact that someone has developed a better chip is interesting news, but it's hardly earth-shattering.
The real reason why dishes continue to outsell most other types of antennas is cost-vs-benefit ratio. They're cheap, they provide a "good enough" signal, and they get the job done.
Cogito, igitur comedam pizza.
The older analog receivers required more bandwidth per channel. Modern satellite TV is digital, the compression means each channel needs less bandwidth, and will work with lower SNR than the analog channels.
It's not just the LNAs. It's also that we are no longer using separate LNA and LNCs. Less parts means less signal losses.
I can remember having to choose a feedhorn, then the LNA, then the optimal LNC and worrying about terrifying coax losses trying to get the signal received and down converted and in the house. Sure it worked but it could be interesting when it didn't.
Now, all of that is handled right in the LNB and the whole part is $40 new, or less at flea markets. This is the unsung innovation of DBS. Stuff that used to be close to home brew or at least contain a good deal of magic is now off the shelf and stuck on the sides of millions of homes.
1 - EXACTLY! I'm not going to retype something that is clearly spelled out. This is slashdot, not my PHD dissertation... Or my weekly article in Wired...
2 - You are correct, but that is NOT what I said.
3 - The Articles I found about it are wrong then, all info I could find mentioned they were closer. got any links to details on that so that I can read more on it?
Do not look at laser with remaining good eye.
I replaced the 18" oval dish that normally comes with DirecTV installs now with an older 1 meter K band dish. I used the LNBF and cables from my current install - just replaced the cheap metal dish and mounting arm itself. Why did I bother? I used to lose signal whenever the rain got to over about one inch per hour. The service terms actually warned of possible losses for any rate above 1/2 an inch per hour, so we can safely assume the old dish was an above average install. I had a spare 1 meter dish that I acquired doing a free to air steerable install, and so it cost me nothing except time sighting the system in. The new version has never lost signal during severe weather. Now ask yourself one more question and the point should be clear - Is it more likely to be raining less than 1/2 inch per hour when they broadcast a killer F-5 tornado warning, or more than that?
See, it's your statement about "small dishes now do similar things that the old big ones did" - the design specs for the original 1 meter disk specify two inches of rain an hour, and the new ones specify 1/2 an inch. The people who sell them don't claim the new design does everything the old one does, they promise only 1/4 of the performance in that one particular respect. 1/2 an inch of rain an hour is now that extreme end of the broadcast range you thought was only about talking to the Mars Observer. (And that's measured well south of, say, New York City or Toronto or Boston, where the line of sight is passing through much more thick air. See, we are operating on the fringes of the feasible much more than most people recognise).
Incidentally, you can get cheap K frequency transparent plastic domes to fit the concave face of a full meter dish, so it offers less wind response than an unshielded smaller dish, further improving your reliability. I found out about those because the NOAA lab and the local police and fire stations all put them up at the same time and there was a piece in the local paper about it. I don't think anyone bothers to make those for the little dishes.
This is still a neat technology though. If I lived in an apartment where a full meter object on the roof was awkward, I'd be looking into it more.
Who is John Cabal?
That's why God invented FEC. Isn't it?
http://www.bbc.co.uk/rd/pubs/reports/1970-27.pdf
Now add variable delay lines and there you go.
You can watch it in action with a google earth plugin, but you have to fight with the camera to see what is going on. I know I have seen a good real-time animation before, but I can't remember where. It might have been J-track.
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No. An analog receiver could work with way worse signals. The image wouldn't be good but there would be an image, while the digital receiver would state something like: "no signal". Many a farmer in my area was appalled by that. As many educated people have stated: the frequency is the change that caused the dishes to be smaller.
Well, I might have a way, but it only works on a semi spherical planet in a vacuum.
You can get a phased-array receive antenna now, to receive satellite TV on your SUV or RV while driving. This has been a common military technology for decades.
One for stationary use could be simpler. The mobile units have a full GPS/inertial/compass setup, so they know where to aim as the vehicle moves. A stationary unit doesn't need all that. It can just scan around after installation, find the desired sats, and store the direction.
The sad thing is that some people consider this an "invention". Just another random giveaway by people who make it their life's work to destroy the U.S. economy.
Not having read TFA, I bet it has something to do with synchronising the signals of the different part of the array...
Privacy is terrorism.
Yeah, I should be a well paid politician :)
"The likes of Facebook and WhatsApp are free to those whose privacy is of zero value."