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Glass Antenna Turns windows into 5G Base Stations (ieee.org)
376 points by thunderbong 52 days ago | hide | past | favorite | 138 comments



I'm all for more innocuous cell antennas. I'm just not convinced in this case. Just looking at the picture it seems neither innocuous nor particularly transparent even thought it's on glass. Maybe they can make the connections less apparent without exposed coax, and maybe they won't need to add (extra) windows on top of windows, and maybe they can make the conductive areas more transparent, but this is only useful as a proof of concept.

Let's see what they can do for a commercial product. Usually, there are tens of antennas on a single tower so they can't all look like this. Also, I'm going to assume that you have to keep anyone from getting within 3 meters just due to radiated emissions, so don't go just looking out that window!


This is a commercial product, that’s actually been installed and being used. The magic here is a “transparent” antenna. The magic is a carefully tuned, small and innocuous antenna, that when mounted on a window it’s been tuned for, allows 5G to easily propagate through the glass.

Glass facades almost universally use Low-E glass to avoid turning the building into a huge greenhouse. Problem for 5G, is that low-e glass is remarkably good at blocking 5G frequencies[1]. Pair that with 5G smaller propagation distances, and issues of finding viable locations to mount 5G antenna becomes a real problem.

This product neatly solves that problem by allowing carriers to mount these antenna on the inside of a buildings facade, while providing coverage outside the building. Which will substantially reduce the cost and difficulty of installing 5G masts. You can place all your sensitive equipment in normal building voids, without the need for bulky and ugly weather proofing, and you need to break the buildings weather tight seals (which a landlord isn’t gonna let you do without significant assurances you’re going the cover the costs of any water that comes through) to run cables to external antenna.

To make all of this viable, someone has had to do a fair bit of work to figure out how to build an antenna that effectively incorporates the low-e window it’s attached to, into its RF design. The fact the physical antenna is made of glass and partial transparent isn’t actually the interesting part. That’s likely been done because glass is a very rigid material that will make it easy to ensure the conductive parts of the antenna are kept at a specific distance from the window it’s mounted on, to ensure the correct RF coupling occurs.

[1] https://www.ranplanwireless.com/gb/resources/low-e-glass/


I like that this also solves the problem of historically there being bad reception in between really tall buildings downtown. If you can embed towers in the facade of a building this problem is significantly reduced.


Ok, so this is the final commercial design. It's inside the window. You can see the electrodes on the small glass sheet (100cm x 25cm?). There are 8 coax connections to 8 patch antennas. They don't cover the entire window and since I can see them they aren't very transparent (that's pretty normal for off angle low resistance ITO since you can't easily match the index shifts with AR films). The antennas aren't very big (why would they be for GHz+ frequencies) and they still have to go through the windows.

I don't know that a white box on the inside of the same window (which covered the wired coax connections) would be that much more conspicuous, especially from the outside. Maybe they require special exterior windows, but those don't seem to be part of the very visible "transparent" antennas. If you lowered the drop ceiling anything would be less conspicuous on the inside.


> If you lowered the drop ceiling anything would be less conspicuous on the inside.

The product is for fitting into existing buildings, with minimal impact. Being inconspicuous is a secondary concern, it only needs to be inconspicuous enough to not be obvious. Drop the ceiling on an entire floor to hide would not be low impact.

As to a plastic white box, sure you could do that. But it would be a plastic box that contains some kind of antenna on a rigid substrate. At which point you might as well just use glass as the substrate, and get rid of the extra enclosure, and manufacturing fiddlyness involved in assembly.

The cost of a glass antenna vs one housed in a plastic box is going to be negligible compared to overall cost of the installed equipment. At that point you might as well just use glass, simplify the construction and install process, and get a product that’s less visually distracting as a bonus.


PCBs and antennas in general are cheaper than glass. I think that's why this is considered special. Also note that they can do UWB and all sorts of other things. It's not like these glass antennas are using a substrate that already exists, they're just mounting something with exposed wires to a semitransparent 1ft/3ft piece of expensive specialty glass. Any change they have to do to the low e windows, they have to do for both.

The idea that a plastic enclosure is difficult, expensive, or fiddly, is kinda hilarious. Maybe you'd like your monitor or laptop or microwave oven to have it's fiddly enclose removed, but I don't think it's wise.


I'm a little disappointed this IEEE article doesn't give any technical details. As an EE, I'd like to know what they are using for the antenna wire conductor. The quote from the article says it's a transparent conductor, which I've never heard of.

“I don’t think the idea for using transparent conductive materials as an antenna existed before"


You're almost certainly peering through transparent conductors right now as you read this comment: https://en.wikipedia.org/wiki/Transparent_conducting_film

The rest of the design is just the usual microwave antenna black magic, but with a different propagation velocity plugged in.


The touch screen on your laptop/phone are definitely made with "transparent' conductors. These range from ITO and Silver Nanotubes on LCDs to patterned aluminum mesh (Samsung's OCTA is On Cell Touch AMOLED) and semi-transparent cathode (~10nm Ag/Mg ground current return layer) on OLEDs.

Those electrodes are literally used as capacitive antennas to detect the position of your fingers and they range from about 300ohm/sq to 1ohm/sq. Depending on the capacitive coupling they range from GHz to 100kHz bandwidths.


I was trying to understand if "transparent" was literally a property of the metal, of if it just means "so thin that you can't see it".


That depends. For ITO it can be quite transparent (80-90%), if you do a good job of matching the index of refraction (otherwise you get weird yellowish reflections and blue transmission). For the nanotubes and metal mesh, it looks fairly neutral (grey >90% transmission), if they do a good job darkening the metal so it doesn't reflect. The OLED meshes are only 2-3um wide and actually aligned with the display sub-pixels (to allow their light through) and their reflections are blocked by circular polarizing films which help make the display black as well.

Just for clarification, the reason that ITO can be transparent even though it is conducting is due to a fairly novel effect where the bandgap of the material is just wide enough to allow most visible light (red-blue) through while still allowing electron conduction (degenerate bands due to Sn doping?). It's pretty cool. Most conductors (metals) have conduction bands that reflect visible light (though they might let X-rays or IR through). Most transparent materials (eg. glass, water) are insulators which have wide band gaps, but no conduction carriers (electrons or holes).

One counter example is Ruby (chromium doped sapphire) which looks red. If you heat it up the bandgap narrows and you it turns dark/black because only IR can get through, while if you cool it in LN2 they will turn light pink as the bandgap width increases!


Indium tin oxide.


See also the Pivotal Commware[0] repeater solution.

[0] http://www.pivotalcommware.com/


> “Usually, there are tens of antennas on a single tower so they can't all look like this. Also, I'm going to assume that you have to keep anyone from getting within 3 meters just due to radiated emissions”

Those towers you see with lots of antennas are massive MIMO installations designed for very high capacity and coverage over a wide area. But not all sites need to look like that. In this case, it’s just a small cell designed to improve coverage within a building and/or on a few local streets. Power levels are also much lower, not all that much different to a WiFi base station. People aren’t going to get cooked if they get close to it.


Do you mean inconspicuous?

- innocuous: not harmful

- inconspicuous: not clearly visible or attracting attention


I think it can be used as "non-objectionable" or "non-irritating" which would still work here


Sure although the article says inconspicuous and transparent and the comment it saying it's neither of those things.


The harm considered here is being conspicuous. So you could make an argument for either term.


Innocuous also means inoffensive, which is apt here.


Innocuous means producing no injury or harm, or not likely to give offense or arouse strong feelings.

https://www.merriam-webster.com/dictionary/innocuous


The transparency is hard to judge from this one photo, where there's a flat background to it and a line or two.

This seems not at all unreasonably subtle to me. Even with the array of feeder lines, yeah, maybe it's not for very high end stash places but for most places this seems ay okay.

Given what the alternatives are for urban and commercial spaces, this feels like a big win.

My main concern is power level. How much power can you emit if Joe in accounting is 8 feet away from it, and how does that compare versus normal building mounted or pole mounted antennas? Also, what frequencies is this antenna designed for; it seems like 5g can run on lots of spectrum; is this mmWave gear or lower?

Apologies for soapboxing, but I want to chip in my belief that this world is driven by those who see possibility & potential.


> Also, what frequencies is this antenna designed for; it seems like 5g can run on lots of spectrum; is this mmWave gear or lower?

The article says it's for the "sub-6" 5G bands, a.k.a. normal cellular frequencies, not mmWave.

As always, these are non-ionizing frequencies, they pose absolutely zero risk to health or safety unless you're absorbing enough power to be meaningfully heated by it.

> How much power can you emit if Joe in accounting is 8 feet away from it, and how does that compare versus normal building mounted or pole mounted antennas?

Assuming an antenna gain of 10 dBi, which seems to be "normal" for panel-style antennas in the 5G low band, just short of 30 watts in to the antenna would be safe according to the guidelines the FCC gives us amateur radio operators for "uncontrolled" environments if the antenna were aimed directly at a person eight feet away.

Obviously in the real world these antennas will be aimed outward so the energy being absorbed by anyone in the building will be significantly less than that.

These should not be installed in places someone could directly touch it or the cables feeding it, but there's no reason to believe there's any danger to someone just existing normally in the same room.


The patent indicates there is a ground plane on the back layer. The antenna is presumably only intended to radiate outside the building.

https://patents.google.com/patent/EP3828994B1


> Apologies for soapboxing, but I want to chip in my belief that this world is driven by those who see possibility & potential.

Cynics never lose but optimists win.


Sometimes the only winning move is not to play.


> My main concern is power level. How much power can you emit if Joe in accounting is 8 feet away from it

That was my first takeaway from the photo from outside. The kinds of antennas they put on top of buildings routinely run many hundreds to a thousand watts or more of power directionally out into the city. That's fine when you're putting it on equipment outside the building on a controlled access roof pointing away from the occupants in the building. Everyone actually in the beam pattern is going to be far away from the active elements.

This design doesn't seem to be incredibly directional especially outwards. You're not going to be able to run much power on that antenna, and now you're going to have it on the inside of metallized glass. A lot of that energy is going to stay in the building. I wouldn't want the desk next to this if it's going to run even 100W. Just asking to get some good RF burns.


> ”A lot of that energy is going to stay in the building.”

Right. The point of these small cell sites is usually to improve coverage within the building.

Occupational RF exposure is pretty strictly regulated in most countries. I’m sure there is design/installation guidance to ensure they stay well within legal limits.


> The point of these small cell sites is usually to improve coverage within the building

That's not what the article is stating. If that was its use, there are plenty of 5G antennas that can look like any of the other warts commonly found on office ceilings like smoke detectors and other wireless ap's and what not.

> attached to a building window inside and turn the outdoors into a service area

These aren't specifically for indoor coverage, its specifically for outdoor coverage.


This is a demonstration setup to show that it works.

It's fairly obvious that there are thousands of different ways to camoflauge this equipment in a real-world customer deployment, just like how routers, etc., are hidden in restaurants and stores.


> My main concern is power level. How much power can you emit if Joe in accounting is 8 feet away from it, and how does that compare versus normal building mounted or pole mounted antennas?

My thoughts exactly. Who would like to sit that close to a 5G Base Station?


I don't think it needs to be fully invisible. There are a lot of places in the building where slightly darkened glass panel would not look too out of place, as opposed to a bulky ugly opaque plastic box. Especially if architects really work on integrating it, it can be made very unobtrusive without needing 100% transparency. And, in a lot of buildings there are glass panels which aren't within the foot traffic areas - high windows, ceilings, technical areas, etc.


> Especially if architects really work on integrating it

How long will be the useful life of these antennas be, compared to the useful life of a building that is still early enough in planning for significant integration?


> as opposed to a bulky ugly opaque plastic box

I've never heard a single person complain about wall/ceiling mounted WiFi access point. Do you really think this is something that justifies the added complexit


But this is not wifi, this is mobile antenna, they are usually significantly more bulky. I have no idea if it's justified on the sum of all things, I'm just saying it's a viable idea.


That's the connector. You're missing the fact that it uses the entirety of the rest of the window


> turns a window into a base station that can be attached to a building window inside and turn the outdoors into a service area

You could easily enclose this by some architectural feature on the interior of the building or even use a window that's off the back of a maintenance closet.


Sure if you’ve designed the building around housing an antenna. But I don’t think carriers want to pay the cost of major architectural changes to buildings, so they can better incorporate new 5G antenna.


Is it possible to create a mesh 5G network run by volunteers supplying their connectivity, thus remove the need for mobile network operators?


I participated in community mesh networks for years and even did a startup where people could get paid for installing mesh nodes on their roof. Many others have done this as well over many years, and have either pivoted (Meraki) or gone out of business and sold their assets to conventional ISPs (Common Networks).

The biggest hurdle is that reliably running high performance transmitters is not easy for amateurs, and the payoff for any one transmitter is not that much. I'm going to use the example of a residential ISP but this applies to cell networks as well. The "meshier" the network is, the more people revenue needs to be split between, exacerbating the problem.

Another issue is that reliability is extremely important for internet access. Given the fact that amateurs are not going to be able to maintain high uptime, for a decentralized mesh network to succeed at actually providing internet service, you need to have a lot of redundancy in any given area, further reducing income from any one node.

The solution to this is to have a team of technicians that can go around and fix and optimize nodes as soon as there is any problem. This is basically what an ISP or cell carrier does. An added difference is that in a mesh network, the idea is generally that the property owner owns the node, while with a conventional ISP, the property owner leases to the ISP who owns the node. Property owners generally prefer the latter, since this is the model they are used to operating under as landlords.


Do you think that this could be linked to a decentralized system for paying people to do this ? Similar to bitcoin, when a node goes down technicians arrive and are payed after the node has been fixed. (I see a lot of potential problems of "measuring" how much the node is repaired, who pays for it etc though)


A big problem that comes up a lot when trying to think of ways to replace a centralized business is that the friction inherent in a decentralized system costs more than the profit margin of a centralized business.

An end user wants to pay a steady monthly fee for internet that never goes down. A property owner wants to get a steady monthly check for leasing a site. A technician wants to get a steady salary for fixing nodes.

A decentralized repair network is likely to reduce reliability for end users, predictability for property owners, and job security for technicians. All three of these parties may find it more optimal to have an ISP business which can finance and coordinate things, even if the business is taking profit which could have gone to the other participants.


Apologies for the cynicism, but that immediately makes me think of a node owner dropping a tinfoil hat over their node, waiting for an ACK from the technician, then taking it off again and splitting the "repair" money with the technician. Lather rinse repeat. It could even be automated.

You'd just need one crooked technician who can recruit some number of node owners. (If the tech did it via remote-controlled power interruption and only did it on scattered nodes in areas with lots of redundancy, they wouldn't even need to recruit node owners and split the cash. But they'd also be leaving evidence that could easily get them in trouble once someone started getting wise to it.)


how about reversing it and paying users for a mixture of uptime and quality of service?


Is it possible? Sure, its possible. Would it actually be feasible and good? Probably not.

Take a look at WiFi-dense apartment buildings. So much crowding, no centralized assignment or management of the bands. It is a wild west of people transmitting on whatever channels and whatever power levels they want (within the legal limits). It ends up with few people actually having a good experience when there's no centralized management. 5GHz/6GHz makes WiFi more usable because it naturally limits your ability to hear your neighbors. Going to 700MHz/900MHz/1.2GHz (the normal frequencies used in a lot of 5G deployments) is only going the opposite direction of where WiFi has been going to solve this problem. Expect more noisy neighbor problems as you lower the frequencies.

Then we're not only going to saturate the bands with people doing whatever they want (within legal limits), we're going to depend on mesh routing through all that noise? There goes your reliability and efficiency of sending data.


I'm talking about creating a single mesh network, not a Wifi-like situation with many networks on the same bands.


There is no difference in the end. It is still a single collision domain for everyone talking.

And who's to say they want to join your mesh and not Bob's super awesome mesh? Or start their own mesh? Oh, you get to decide how to operate the mesh but I can't? I guess you'll end up getting some kind of license so you can standardize how this particular mesh should operate and prevent others from running competing services on the same frequencies as your one mesh.

You'll put out standards on what kinds of devices are certified to work on it and ensure certain settings so tx/rx errors are reduced to ensure good usage. You'll start encouraging people to not put up more nodes in a certain area because it's just getting too crowded here, but hey we need to incentivize someone to set up a node on the other side of town.

Snap now it seems like we're running a regular carrier.

I participate and use city-sized WiFi mesh networks in the amateur radio world. They're not anywhere near a replacement for what normal people think of as internet connectivity. I can't imagine swapping WiFi for 5G cellular stacks would end up making a radical difference. The issues are largely with having to make multiple wireless hops, mesh routing inefficiencies/problems, and having everyone actually play nice all the time.


How do you prevent selfish leechers that use network bandwidth, but don't contribute to it, like on public torrents? Using people's cellphones as relay nodes is a non-starter because it's going to be a massive drain on battery life, so you'll have to rely on volunteers setting up their own wired base stations.


That should be fine. If it's part of every modem/gateway router, there should be so much bandwidth it doesn't matter. Standard QoS techniques can apply - don't allow someone to take it all when there are more people who want bandwidth.


>If it's part of every modem/gateway router, there should be so much bandwidth it doesn't matter.

Why would it be part of every modem/gateway? Since there's no monetary incentive to participate, in all likelihood all nodes would be run by volunteers who are shelling out extra for a compatible modem/router.

Actually come to think of it, you can run a volunteer network providing internet connectivity with off the shelf equipment right now. It's called setting your wifi network to "open". Why don't people do that? How would your mesh network fix those issues?


Not only just shelling out more for that compatible modem/router, that volunteer would also have to be willing to set up at least the antennas in a place optimal for others to actually use it instead of potentially optimal placement for their own services. A client on the street is not going to get good connectivity to someone's cell repeater tucked deep in their media cabinet next to their game console and under their TV in the center of their home. You'll need to get your volunteers to bother placing these antennas on their roofs, on the top of flagpoles, etc. to get good propagation. They better have properly grounded it as well and put fourth good lightning protection for this new wire high point at the top of their home.


> If it's part of every modem/gateway router

That's not really a "mesh" then. It is just a bunch of infrastructure AP's everywhere.


Why is it not a mesh? There are fundamental differences between normal and mesh networks in the ways they route packets, and I think this is still a mesh network.


> If it's part of every modem/gateway router

If it's a part of every modem/gateway router, why would you bother routing it through a bunch of mesh hops just to eventually get out instead of just routing it through the far more reliable wired networking available at every modem/gateway router?

Those regular WiFi networks only have tons of available bandwidth because they're not trying to repeat a bunch of wireless traffic. Even the current mesh WiFi networks only really work when you're using frequencies that aren't trying to compete with neighbors. Start getting actual density and it'll all fall apart.

Also your idea of "standard QoS can still apply" isn't exactly true. That QoS is only going to work if people play along with it. In the end its a shared medium. Get some clients to not play along with your configurations, you'll start getting collisions regardless of what you configure your QoS settings.


If it isn't doing mesh routing, then it isn't a mesh.

The question is can devices connect to other devices that route to router with internet. Is it possible to have router for house without internet connection that routes to the neighbors that do?


Yes, that should be possible.


> If it's part of every modem/gateway router, there should be so much bandwidth it doesn't matter.

The bandwidth you care about in this scenario, where you don't have backhaul, is in the air. And very limited.


5G for just internet is somewhat doable, but unlikely reasonable. There is a volunteer-driven LoRaWAN Helium[0] mesh network which added 5G some 2 years back. But it's cryptocurrency-driven and apparently unprofitable for volunteers investing in radios and antennas. At least where I live.

My neighbor still has the Helium antenna and radio on his balcony but it's offline due to costs/profits disproportion. It's the LoRaWAN, pre-5G hardware though, and I don't know anyone running the 5G version, if it's even a real thing. I liked the idea from technical perspective but the project itself was off-putting for me due to being built around a crypto token and having overall web3 smell.

[0] https://en.wikipedia.org/wiki/Helium_Network


There are a few problems with this. Mesh is cool for other uses but can't replace the infrastructure of mobile operator.

One, what frequency are you going to use? If you use 2.4GHz or 5GHz, your Wifi-using neighbors will hate you. There is the 6GHz spectrum but has problems with long ranges. The 3.5GHz CBRS is probably the best bet but that requires spectrum allocation and organization to run it. The mobile operators have all the good low frequency, long range spectrum.

Two, the range with home routers is going to be pretty short, maybe 1mi. That means lots of node to cover a city. Also, 5G routers are not that cheap. It also means that there will be no reception away from the city. Most routers are meant to be used inside, and good coverage, requires mounting them outside on a pole.

Three, I'm not sure there is 5G device-to-device. There was LTE-Direct but it never got implemented. There D2D in 5G spec but I can't find any implementations.


Yes it is possible. However, it would probably require regulatory changes. It would really suck to have your internet shutdown because someone was pirating movies on the mesh.


Let's start with the technology, then it can be used to argue for legal changes.


I think the technology is already there to hook into a 5g network and repeat it. However, you would need to create a network "Provider" for the mesh. Then you would need to connect all the nodes. In the end you have made one more wireless company. I think the governance model for the mesh provider would be way more important than the tech itself.

However, creating the Wikipedia/Internet Archive of wireless ISPs would be pretty awesome.


Connecting the nodes through a common backbone shouldn't be necessary in a mesh network. Nodes can provide connectivity by relaying even if they don't have access to internet directly.


You still need a governance model for the mesh. IP, NAT, anti-DDOS, certificate authorities, emergency services, phone network integration, etc... Otherwise you just end up with the worlds biggest open wifi network. About as safe as a hat full of mercury fulminate.


Yes via sidelink: https://www.abiresearch.com/blogs/2022/11/08/5g-sidelink/

Not used everywhere, but seen as something that would be rolled out for critical communications, natural disasters, etc.


There's some specs out for 5G on unlicensed bands, but even that uses licensed bands for coordination.

So, if you want to run legally, you're going to need spectrum licenses and transmitter licenses and all that. That will make you a mobile network operator, regardless of how you arrange labor and sites.


Not sure I'd classify this under "volunteers", but you can run a 5G hotspot on the Helium network: https://www.helium.com/5G


It feels like they've partially given up on the whole Helium 5G model as much as it still exists. Their current sham is instead to rely on user-installed Wi-Fi hotspots that use Passpoint 2.0 it looks like, and they're steering more adoption of their cursed WiFi implementation.


Helium 5G in USA is doing exactly that, CBRS powered.


mesh is a pipe dream

change my view



That's less a "mesh" than it is a community-run WISP.

Mesh would be each home (or some percentage of the homes) act as nodes. These have all the homes hit a few towers around the city. Traffic isn't routed directly between (or through) the homes in this example, it is all centralized. They hit a single big tower that then does all the routing.


The link in the Vice article to the project's site is old. Here's a current one; https://detroitcommunitytech.org/eii


Maybe we’d have a chance if you told us why you have that view in the first place.


You're absolutely correct. People have been trying for decades and it's never gone beyond toy deployments. Even scenarios where it would be critically useful such as mobile military haven't really made it work. The latency problem is unfixable.

(It doesn't help that people in this thread are confusing "mesh" with "collection of access points each of which is individually connected to a wired ISP", which is not a mesh.)


Can’t find an article but I thought emergency services used an old mesh network for emergency communication in NYC on 9/11? Could be wrong though since I can’t find anything on it


Why is it a pipe dream? It could also be something like roaming (in foreign countries), whatever - just a community mobile network that anyone can join.


If you're talking about wireless-only mesh and using it as the only form of connectivity, sure, you're right. If it's just another way to connect then it is very practical for use in high-density urban areas, but highly unlikely to be widely implemented as ISPs are the main distributors of the most suitable node devices and they are the ones with the most to lose if mesh is easily available.


> I don’t think the idea for using transparent conductive materials as an antenna existed before

Many slightly older cars (2000-2020) had antennas embedded in glass. The idea is solid. Antennas in glass are protected, so they can be very thin and almost invisible, more aesthetically pleasing than a shark fin or a rod on the roof.

I would consider this an aesthetic choice, not so much engineering. A small antenna sticking out on the roof solves the engineering problem adequately.


They still do, I believe. Cars usually have several antennas embedded in e.g. the rear glass. Even something like the FM radio often has 3+ antennas in different locations and the receiver switches between them to get the best signal. One shark fin isn't enough.


Now shark fins are in vogue again because they house multiple antennas — FM/AM, DAB, GPS, and recently more importantly, 4G. Maybe even WiFi — weird as it sounds, I saw some strings for WiFi antennas in a popular stock media/head unit’s firmware.

Though you are probably right and many cars with just FM/AM and DAB still put them in windshields.

I’m not sure about that 3+ antenna claim for FM. Do a fact-check there. ;) I think most diversity antenna systems that you describe use 2. And they are still considered “premium”. 3 is a bit overkill for FM, FM is very resilient against obstacles.

If I’m wrong, would be interesting to see an example of a car that uses 3 or more. Probably far outside of my pay grade to say the least.


I'm going by the BMW E90 (Top HiFi option) which has 3 physical FM antennas FM1, FM2 and FM3, all in the rear glass, and a fourth "FM4" which is not a physical antenna but a combination of FM1 and FM2.

They really didn't want you losing signal!

This isn't even mentioning the festoon of other antennas for DAB, mobile (which has a backup too and phones home in a crash: in case the shark fin is broken in a crash)


I could be wrong, but E90 with the best HiFi package is a very rare exception to the rule. I wouldn’t say you often see such configurations.

It’s cool they did that but it’s almost like they are trying to prove some point — maybe to be the best in the market for FM by a hair. :) One antenna is more common than 3 to my knowledge, by far.


Fair enough, I just happened to have an E92 and one day I read all about its systems when it had some major electrical issues :) (Turned out they were due to someone forgetting to clip a piece of harness back in place after some work, and as a result the harness rubbed against something in a wheel arch, eroding the insulation and letting water in intermittently screwing up the CAN bus!)


My (old) E36 BMW had a switched multi-element array in the rear glass that served as the FM antenna.

It had a magic box that used feedback from the stock radio's IF section to (try to) erect the best pattern for good reception at any given time, and which presented one unified RF output to that radio's singular input.

Cadillac has used the same, or very similar, system as well.

Which is neat and all, I guess, but we seem to be getting off into the weeds: These antenna elements were not invisible at all except for the fact that they blended in with the heated defroster elements that were also printed onto the glass.


> WiFi — weird as it sounds, I saw some strings for WiFi antennas

This is probably so the car can act as a Wifi hotspot, with the Wifi antennas located in the interior rather than in the sharkfin.


Sometimes both. My car can connect to my home's WiFi for its software updates. I doubt that antenna is inside the cabin of the car.

It also can act as a hotspot if I bothered paying for its data plan. I'd rather if I could just load an eSIM for my existing service to have it be a hotspot for me. Since its antennas are on the outside it should get way better GPS and cellular connectivity than my phone in my pocket deep in a metal box.


I've seen strings for selecting a WiFi network in an SSID list :) I'm guessing for OTA updates when the car is at home or there is another use that involves your phone's hotspot.

I've seen what you are talking about, too. My VW RNS had settings to use the car's 4G for passenger WiFi.

Cars really want to phone home these days


I'd like to see a version that doubles as exit signage.

https://www.exitsignwarehouse.com/products/esw-el-r


They do that in this article towards the end: https://wavebyagc.com/en/hidden-antennas-for-urban-environme...


Very cool, thanks. It looks like they can be used for WIFI as well, which would make these perfect for business mesh networks.


The new HSR trains in my country use similar tech to improve cell phone reception while traveling

https://press.siemens.com/global/en/pressrelease/obb-puts-fi...


No. The article is about windows as active antennas. Meanwhile, trains now start having permeable windows that let the radio coverage from outside through. Train windows are metallized to protect from the sun - unfortunately blocking radio waves as well.


Maybe not in your country but I know there's cell repeaters all over civic infrastructure in Europe


It took me a moment to realise this is about window not an operating system even though 'windows' was lowercase


Exactly the same here... Same happens when I see the word 'file' written somewhere (which in Italian means queues, and I'm Italian), and I read it as the English IT word 'file'. This always make me lightly smile.


What or which "teams" are you taking about? Oh, the Microsoft Teams' teams.


Won't tapping on the glass disrupt the signal, or simply wind or heavy rain against it disrupt it as well?


It would if this was actually mm-wave 5g. The article says this antenna only functions in the sub 5ghz range, which makes a lot of sense.

Most modern windows use an aluminuzed coating for UV reflection (usually called low-e glass), which surprise surprise, is absolutely great at attenuating mm-wave frequencies, making windows pretty much the worst possible place on a building to place an antenna.

But, turns out most people also dont need gigabit wifi for their phones and other devices, so true mm-wave 5g seems to mostly be reserved for wireless home internet at the moment.


Would this work with peptide glass?

"A self-healing multispectral transparent adhesive peptide glass" https://www.nature.com/articles/s41586-024-07408-x :

> Moreover, the supramolecular glass is an extremely strong adhesive yet it is transparent in a wide spectral range from visible to mid-infrared. This exceptional set of characteristics is observed in a simple bioorganic peptide glass composed of natural amino acids, presenting a multi-functional material that could be highly advantageous for various applications in science and engineering.

Is there a phononic reason for why antenna + window?


Bass kickers, vibration speakers like SoundBug, and bone conductance microphones like Jawbone headsets are all transducers, too

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

https://news.ycombinator.com/item?id=41442489 :

> FWIU rotating the lingams causes vibrations which scare birds away.


The photo caption reads: "An interior photo of a rectangular glass device attached to a building's window, with cables going between it and the ceiling."

But it is clearly an AI-generated image. Look at the reflection of the lamp in the window, it overlaps the window frame.

Is this now the norm, AI-generated images pawned off as begin real? Good lord...


The company Alcan Sytems also produces 5G glass antennas. But they use LCD (Display Technology) to create a phased array to dynamically direct the signal. https://www.alcansystems.com/


So you are telling me this looks better than a simple dish antenna resembling a Unifi AP dish? This thing might be a concept, but when it is implemented, it will still show a bunch of wires encased in glass. I am also not into being blasted by radio waves all day long from every angle.


What advantage does this actually confer over just a normal antenna you place at the top of your window? The "look it's glass!" hype claims it won't obstruct your view, but on an 8ft tall window, nothing is obstructing your view up there anyway!


The entire window itself is the antenna, and that antenna is transparent.

The shit you see at the top are the wired connectors for the antenna that is inside of the window.


how do we end up with statements like 'millimeter waves can deliver typically between 10 and 50 GHz of bandwidth' getting published in ieee spectrum? are there no electrical engineers at the ieee anymore? apparently this article is by a 'tim hornyak' with a degree in journalism from carleton university in ottawa. what the fuck?


Is "between 10 and 50GHz" not a description of a range of widths of a band?

Are bands of that width not typically delivered with mm waves?

(There's more definitions of the word "bandwidth" than counting bits per second. It has, at least, uses in both RF and in data networking -- and the former use is predates the latter.)


10 to 50 gigahertz is a range of bandwidths, yes. that's not the problem

i don't know why you're bringing up bits per second. neither i nor the clueless loser who wrote the article were talking about bits per second

the quote doesn't say 'designs that deliver 10 to 50 gigahertz of bandwidth typically use millimeter waves'. it says the opposite: 'millimeter waves can deliver typically between 10 and 50 GHz of bandwidth'. that's clueless nonsense. it's not even wrong. bandwidth is delivered by a medium, not by a signal in it; the signal is closer to being what the bandwidth is delivered to. the signal occupies or consumes or has bandwidth, which is close to the opposite of delivering it. and a millimeter-wave signal can be of any bandwidth at all up to about 300 gigahertz, including—obviously, one would hope—bandwidths of well under a megahertz. (in theory you could transmit or detect a millihertz-bandwidth millimeter-wave signal, but that probably requires exotic instruments like an atomic clock.)

it's complete nonsense to try to describe the 'typical' bandwidth of a millimeter-wave signal. it's like talking about the typical mass of objects made out of atomic matter, or the typical distance traveled by photons. is jupiter or a tardigrade a more typical-sized atomic-matter object? it depends entirely on context. there is an upper limit (objects much larger than jupiter will stop being made of atomic matter pretty soon) and a lower limit (probably you need at least a dozen or so atoms of lithium before you have an 'object') but there are many orders of magnitude of slop within that limit

if we were talking about bits per second, it might make sense to talk about a signal delivering something, but even in that case the information capacity of the signal depends on many more considerations than just the wavelength. the bandwidth, for one, but also the relevant sources of noise, the transmit power, the path loss, and the efficiency of the coding scheme used. so you'd still have a lot of orders of magnitude of slop, and plenty of mmwave signals aren't even used for communication, so trying to characterize their shannon capacity is a somewhat questionable enterprise


It's not nonsense, though. It's just a generalization.

Here's another generalization: A car typically weighs between 1 and 3 tons, and typically travels on the highway between at speeds between 50 and 80MPH.

This generalization misses (many!) rather common outliers, and that's OK since it not meant to be particularly precise. That's the way of generalizations: They're generalized.

Meanwhile, please take a moment to read this: https://news.ycombinator.com/newsguidelines.html


yes, i agree that it's reasonable to talk about the typical weight of cars. that is because they vary over many fewer orders of magnitude than the weights of objects made out of atoms or the bandwidths of submillimeter-wave signals, so it makes sense to talk about 'outliers' and edge cases such as golf carts and tanks. by contrast, there is no sense in which that is true of the bandwidths of submillimeter-wave signals, in part because they are mostly not of human origin, so your implied analogy is invalid

but, as i explained, that's not the only dimension along which the statement is nonsense; millimeter waves also don't deliver any hertz of bandwidth. it's a really multifaceted gem of cluelessness

the implication of the last line of your comment seems to be that you think i am not familiar with the site's guidelines, but it is unclear why. perhaps you think criticism of the ieee's editorial and human resources choices runs counter to the guidelines? perhaps you think there is nothing to be learned from my criticism? you'll have to be more specific if you want to have a substantive conversation


I think that your directly-insulting attitude is undeserved, unnecessary, and that it is also counter to the general good.

I have nothing further to discuss.


my criticism of the ieee is deserved, necessary, in the public interest, and, furthermore, substantial and informative. why does it bother you? is your sister editor of ieee spectrum or something? obviously you're not tim hornyak because if you'd graduated from journalism school you'd be in favor of robust, substantial criticisms of public institutions like the ieee when they're failing society like this, and you're not an electrical engineer either


Why the hostile nature of your question? Sounds like there's some context to note.


because i think that kind of ignorant schlock discredits the ieee as an organization


I'm exited to see if an array of antennas in the glass can 'beamform' in the building and increase signal strengths intelligently.


This device in this article seems to be mainly for serving signal outside of the building. However, devices like the one you descibe exist, such as: https://pivotalcommware.com/echo-5g/

(Full disclosure, I'm a previous employee)


So give it a few years and all new car windows could be mobile network antennas?

Can imagine both good and horrible points to that happening.


Why not just make a hawk silouhette into an antenna? They paste those on windows all the time to minimize bird strikes.


This may be out of context, but I wonder if this will have any effects on cell tower REITs.


Next step is to develop the use case for smartphones, then for foldable smartphones.


Perfect for businesses in San Francisco :D


Does that mean we’LL no longer need vaccines to get 5G at home? :D :D

More seriously, the terrible nature of start up/project names meant I actually read this as being

“Glass Antenna[software name] turns windows [operating System] in base stations [an actual base station or network hub]”

And it was not until I saw Ieee.org that I realized it actually meant real antennas, and even then my incorrect interpretation of the headline still seems plausible to me


Which way up is that picture?


Pretty sure we're lookup up at a slight angle. Those high hat lights are usually on the ceiling and not walls or floors.


The product website has a bit more helpful pictures: https://wavebyagc.com/en/hidden-antennas-for-urban-environme...


I don’t 100% get the story. TLDR, skeptical due to the issue of the two 5G frequency ranges.

> Because 5G networks include spectrum comprising higher frequencies than 4G, base stations for 5G networks serve a smaller coverage footprint.

Sure

> It [the window antenna] is compatible with frequencies in the 5G Sub6 band—meaning signals that are less than 6 gigahertz (GHz). Sub6 antennas represent critical portions of a 5G deployment, as their lower frequency ranges penetrate barriers like walls and buildings better than the substantially higher-bandwidth millimeter-wave portions of the 5G spectrum.

But 4G seems to go into at least the 3-ish GHz range just fine. At least my layman understanding is that sub-6Ghz doesn’t have the range problem, the whole point of adding that (IMO, less-than-intuitive-to-consumers) frequency band was that (while it didn’t fulfill the bandwidth promises of 5G) it also didn’t have the range problem. So it is there to fill the gaps.

The ability to deploy sub-6GHz antennas everywhere seems like it misses the whole point of that band.

I’m sure there’s some advantage to the 5G tech in general, because it is newer. But that’s a different pitch, right?


Sub6 is more or less the same frequencies as 4G. I know there's more low frequency (additional spectrum formerly used for over the air TV), and there might be some slightly higher frequency too, but this is the general purpose stuff. The mmWave stuff is really for locations with dense crowds like stadiums and maybe airports and busy train/transit stations.

5G is still better than 4G on sub6 for lots of reasons, but yeah, it doesn't have the oodles of bandwidth that 5G promised.

Being able to put more sub6 base stations in more places is still good though. There's plenty of areas with poor coverage, and sometimes the reason there's no coverage is the aesthetics of the base stations are poor. Blending in helps. Which is why some antennas look like weird saguaro or palm trees and pine trees. It might be nice to have antennas in windows in office buildings instead hanging on the side, and it might be easier to install as well.


That's not a glass antenna. That is an antenna encased in glass.


The glass and the antenna have been designed and tuned to work together. The antenna will not work without the glass, its part of its RF characteristics.


Agreed, also the article becomes orders of magnitude less interesting once you get past the click bait title.


My first thought was, which windows version does it need? /s


Glass is silicon and silicon is conductive metal, after all…


Glass is a resistor, it is not conductive. Its actually a pretty good resistor, its often used to separate extremely high voltages. Those little discs you often see holding high-voltage power lines are often made from glass.

Silicon is not a conductive metal. Its a semi-conductor, it needs doping to become a good conductor. That's why its used in IC's. Naturally not very conductive but react a little with something else and suddenly it becomes a pretty good conductor. Make a mask of the channels where you want that conductivity, and suddenly you can draw little wires.


Also why this system needs to be customized and tweeked to work with each specific panel of building glass it is placed with to get the full RF signal pass through


It's not using the glass itself as an antenna though:

>NTT Docomo reports that it uses transparent conductive materials as the basis for its antenna, sandwiching the conductive material along with a transparent resin, the kind used in laminated windshields, in between two sheets of glass.


a semiconductor.


“Silicon substrate, as one of the most important materials for the integrated circuit industry, can be used to manufacture mm-wave antennas for a highly integrated purpose”

Here’s an interesting paper on how to make it work efficiently:

https://www.mdpi.com/2079-9292/12/24/4983#:~:text=Silicon%20....


That neither makes silicon a metal, nor glass silicon (it's silicon oxide at best, and oxides generally have radically different chemical and electrical properties than the pure element).




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