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Low-cost 60GHZ phased array antenna (opens in new tab)

(eenewseurope.com)

208 pointsttsda6y ago75 comments

75 comments

47 comments · 10 top-level

jtbayly6y ago· 13 in thread

You can buy a set of pre-paired (configured) devices from Microtik for $195 that are 60Ghz 1Gbit full duplex that don't require any dish. I've used them, and they work well. (https://www.amazon.com/dp/B077992GG3)

The difference here seems to be a substantial increase in distance. 1.5km is a lot more than the 100-200m promised by Microtik.

Also, yes, any 60Ghz device is going to be line-of-sight only.

The "wireless wire" are too short range to be useful for many things. A better example of an 802.11ad product shipping right now is this:

https://mikrotik.com/product/lhg_60g

Or this, which is $299 per end:

https://store.ui.com/products/af60-us

If you're going over 300-400 meters with these you need to keep in mind that the 60 GHz band sees EXTREME rain fade. People try to build links that are too long with these and have no fade margin. RSL should be something like -40 to -42 when properly aimed, which gives you about 20dB of fade margin.

Sure you can get a radio set to link up at 1.5km+ at -60 on a clear sunny day, but the slightest rain shower will have adverse affects on it.

tssva6y ago

With 60GHz it would take a storm with a rate of rain approaching 55mm (2") per hour to exceed a 20dB fade margin. That is quite a severe rain. A slight rain shower should not significantly impact a 1.5km link at 60GHz.

xfs6y ago

The wireless wire is intended for indoor use, where you can move it around. Here automatic beam forming is more appropriate than a dish which means fixed installation requiring precision alignment and very narrow main lobe.

Yeah, but both of those devices are dishes. What we're discussing is what's possible without a dish.

908B64B1976y ago

1.5KM makes 'wiring' a village possible from one relatively high structure, such as a church's bell tower.

doikor6y ago

Line of sight truly means line of sight with 60GHz. As a human standing in the way is enough to mess with the signal so would a flock of birds I guess.

A village that small and unwired, rural, third world, would be happy with that line of sight limitation.

forgotmyacct6y ago

I'm thinking this is primarily point to point, not suitable for showering an area in sweet bits.

It also requires clear weather, so won't be enough to "wire" a village with reasonable expectation of service quality. At which point there is little reason to go with anything, but a passive optical network in a village.

cozzyd6y ago

In good weather...

xfs6y ago

Not line of sight only. Many recent 60Ghz devices with better beam forming also work acceptably well using reflection off solid surfaces.

jotm6y ago

That's... actually impressive. I've built a point to point WiFi link before, with 802.11g.

I was under the impression 60GHz is for extremely short range applications, like wireless connectivity in a living room and such.

Really surprised it works that far, even if it needs LoS and perfect weather.

8bitsrule6y ago

DIYers may find some helpful info here: https://hackaday.com/2015/04/07/build-a-phased-array-radar-i...

gene-h6y ago· 6 in thread

Using 60 GHz for communication at these distances is pretty strange because 60 GHz is strongly attenuated by the atmosphere. Not only that, but atmospheric attenuation peaks at 60 GHz because that's what oxygen absorbs[0]. Some military satellites even use 60 GHz for intersatellite links because it's highly attenuated by the atmosphere, making eavesdropping more difficult

[0]https://en.wikipedia.org/wiki/Extremely_high_frequency#Propa...

jjoonathan6y ago

The next generation of RF communications always clusters around RF spectrum that the previous generation considered undesirable. From shortwave radio to 2.4 GHz, this has always been the case. It's not a huge stretch to suspect that it might be the case for 60 GHz as well.

ColanR6y ago

So what would the most desirable frequencies be for long range ground based communication?

magicsmoke6y ago

The high attenuation at 60 GHz is actually an advantage since it lets you put lots of highly directional antennas in close proximity while attenuating their side lobes to lower interference. If your attenuation is 20 dB/km but you have a 22 dBi gain antenna, a 1.5 km range seems pretty feasible.

blackguardx6y ago

Yeah, this is also why 60 GHz FCC power limits are higher because they don't expect you will interfere with anyone. I thought it was usually thought of as an "in room" transmission medium.

danesparza6y ago

Agreed. 60GHz appears to be allocated for fixed inter-satellite communications (probably for this reason):

https://transition.fcc.gov/oet/spectrum/table/fcctable.pdf

peter_d_sherman6y ago

I read some of the above PDF... what's amazing to me is that a whole bunch of names of foreign countries pop-up over and over again in this document, specifically with assigned frequency ranges, as if the FCC is regulating frequency ranges in foreign countries... Before reading this, it seemed self-evident (to me) that the FCC's regulatory power does not extend to those foreign countries... Although, perhaps the FCC's regulatory powers do in fact extend to those countries via international agreements and/or treaties?

Does someone know?

How does that work?

dillonmckay6y ago· 5 in thread

Is 60GHz band unlicensed in US and EU?

joshvm6y ago

Ish in the UK, see http://static.ofcom.org.uk/static/spectrum/fat.html

Some ranges are usable for Industrial/Scientific/Medical (ISM), and there are exempt low power devices although I leave it as an exercise to the reader to find out which:

https://www.ofcom.org.uk/__data/assets/pdf_file/0028/84970/i...

For example:

IR2030/7/2, wideband transmission systems that are not fixed can be used up to 40dBm between 57-71GHz. Fixed systems are allowed, but not within 6km of certain sites. You can also use it for tank probing radar under various situations. One of them is MOD Hebrides which is a large closed area for weapon system testing, another is Castlemartin training area, and another near Luffenham (no idea about that one). Presumably it interferes with military radios and at least two of those sites are used with live ammunition, so probably it's a safety thing.

jdietrich6y ago

61-61.5GHz is an ISM band, so it's unlicensed pretty much everwhere. This frequency range is heavily attenuated by oxygen, so it has inherently limited range and low risk of interference even at high emission levels.

tpmx6y ago

According to this it is:

https://en.wikipedia.org/wiki/IEEE_802.11ad

Not in the US at least.

60 GHz is unlicensed in the US. Bridgewave and others have been shipping 60 GHz band point to point outdoor radios since 2008.

71-86 GHz ("E band") is light licensed, which is easier and less costly to coordinate than the traditional 6/11/18/23 GHz FCC part 101 microwave bands.

lukeqsee6y ago· 4 in thread

Since it’s in the 60GHz range, that means it would basically require line-of-sight to function, right?

Not downplaying the significance, but I’m not sure we’ll get WiFi at 1.5km just yet because of it.

These types of devices have existed for a while with a dish at least. You're right, at this frequency you need LOS and there's little forgiveness there.

Current products don't really intend (to my knowledge) for you to connect a client directly to this antenna, rather they're meant for both to be in a fixed location properly aligned to each other, then they go to the access points for the clients.

Like the other's mention, this is useful for many environments with multiple buildings, easy example is a shed out in your backyard.

Obviously if you could run a copper/fiber connection out directly that'd be better, but these are for situations where you can't.

Could be useful for backhaul though for mesh networks outdoors

datenwolf6y ago

Something something rain and fog.

wil4216y ago

You could use it to extend range to a large campus, stadium, race track, farm or even between two office builds in close proximity. It’s somewhat niche but there is a use case for short line of sight connection.

tus886y ago· 3 in thread

How does that work when no Silicon runs at 60ghz? What can process the signal?

tomxor6y ago

You are thinking of big CPU clocks, this is not the speed of a single transistor switching, it is determined by whatever was accepted as the longest path of components for electricity to propagate through (think of a ripple adder as a simple example). You can have a much smaller separate clock and thus higher frequency for single purpose silicon when the path is significantly shorter.

60GHz here is talking about signal, you only need to create an oscillation at 60GHz not do fp multiply. There are various ways of doing so, but consider that it only takes three inverters to create a ring oscillator. As for the data - you don't need to fill the buffer at the speed which bits are sent, which is how you can interface with a lower frequency microcontroller, i.e the buffer is filled at a lower frequency but in large chunks i.e words.

Someone with proper EE and signal processing knowledge will explain more accurately but that's the crude idea (components frequency vs clock).

creatornator6y ago

Not sure if this is what you are getting at but high speed comms modulate a signal up from a lower frequency to a much higher carrier frequency for transmission. Then the receiver modulates back down to baseband (the original frequency before modulation). This can be done with discrete hardware, no need to do the DSP with a CPU that can't reach those clock speeds. It's one of the reasons your 5GHz WiFi doesn't actually have a 2.5Gbps bitrate (satisfying the Nyquist criterion), but something closer to 1.3Gbps.

Source: graduate with MS EECE in Comms, Control, and Signal Processing in a couple months

stephen_g6y ago

At those kind of frequencies (and way higher), devices like oscillators, mixers and amplifiers (FETs) are typically fabricated on Gallium Nitride (GaN) or Gallium Arsenide (GaAs) substrates.

richk4496y ago· 3 in thread

Is this just a passive phased array? I can’t electronically steer it, can I?

No, it's active. Assuming they are using their 16 channel chip:

https://perasotech.com/x-series-products/

I'll bet it's two, 32 element arrays (one each TX and RX) composed of 2-element sub arrays.

So where it says support for 16 antennas, that means that there are 16 individual rf amplifiers, and the phase and amplitude of each channel is being set to do the beamforming?

Can a user just put in 16 rf feeds and do the beam steering themself?

If used in the standard form, can it do digital beamforming (send different info on different beams)?

mNovak6y ago

With 22dBi they're quoting, it'd have to be all Tx or all Rx. Unless they're conflating amplifier gain in there, which sometimes happens.

asadkn6y ago· 2 in thread

Says low-cost but anyone knows what exactly is "low cost" here?

With the process technologies they're using, I'd guess 10s to 100s dollars.

For a phased array antenna?

danesparza6y ago· 1 in thread

It can achieve that without a dish because (correct my math if I'm wrong) a full wavelength antenna for 60GHz is 0.1968 inches. So I'm pretty sure the silica includes the antenna.

The antenna is built on a separate substrate, I'm guessing a spread glass such as Rogers RO1200. You can do the aperture calculation here, which for a square aperture at 100% efficiency is 18x18 mm. It's probably more like 75% efficiency.

https://www.everythingrf.com/rf-calculators/effective-antenn...

ldite6y ago

This isn't all that new - I've lost the link to the press release, but this thing will also do 1Gbps+ at 1km: https://www.siversima.com/wp-content/uploads/product-brief-t...

hestefisk6y ago

That’s Hz, isn’t it?

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