Comment by kurthr

Comment by kurthr 10 months ago

37 replies

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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!

avianlyric 10 months ago

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/

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  • SOLAR_FIELDS 10 months ago

    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.

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  • kurthr 10 months ago

    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.

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    • avianlyric 10 months ago

      > 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.

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      • kurthr 10 months ago

        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.

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  • venusenvy47 10 months ago

    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"

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    • kurthr 10 months ago

      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.

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      • venusenvy47 10 months ago

        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".

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        • kurthr 10 months ago

          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!

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Reason077 10 months ago

> “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.

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juancn 10 months ago

Do you mean inconspicuous?

- innocuous: not harmful

- inconspicuous: not clearly visible or attracting attention

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  • Bjartr 10 months ago

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

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    • furyofantares 10 months ago

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

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  • asveikau 10 months ago

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

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  • stackghost 10 months ago

    Innocuous also means inoffensive, which is apt here.

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jauntywundrkind 10 months ago

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.

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  • wolrah 10 months ago

    > 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.

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  • Swizec 10 months ago

    > 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.

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  • vel0city 10 months ago

    > 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.

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    • Reason077 10 months ago

      > ”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.

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      • vel0city 10 months ago

        > 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.

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  • gamblor956 10 months ago

    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.

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  • generic92034 10 months ago

    > 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?

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smsm42 10 months ago

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.

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  • me-vs-cat 10 months ago

    > 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?

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  • bmicraft 10 months ago

    > 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

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    • smsm42 10 months ago

      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.

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homero 10 months ago

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

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4star3star 10 months ago

> 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.

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  • avianlyric 10 months ago

    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.

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