
Low-cost 60GHZ phased array antenna - ttsda
https://www.eenewseurope.com/news//60ghz-phased-array-antenna
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jtbayly
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](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.

~~~
908B64B197
1.5KM makes 'wiring' a village possible from one relatively high structure,
such as a church's bell tower.

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doikor
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.

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chrisseaton
Do flocks of birds regularly hover in one place for an extended period of
time? Coming up with increasingly bizarre limitations here.

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tuco86
They could fly down the beam ;)

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omgwtfbyobbq
Or better yet, oscillate along the path of the beam. And they would naturally
have another flock to swap out when they tire plus another flock available as
a hot swap in case something unexpected happens. :P

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gene-h
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...](https://en.wikipedia.org/wiki/Extremely_high_frequency#Propagation)

~~~
jjoonathan
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.

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

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thetinguy
Probably VHF.

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lukeqsee
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.

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C1sc0cat
Could be useful for backhaul though for mesh networks outdoors

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datenwolf
Something something rain and fog.

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C1sc0cat
Well 2.4 is effected by rain - I think with 60Ghz you would cut the trees down

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

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

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jandrese
For a phased array antenna?

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Robotbeat
Sure, why not? It depends on the number of elements, of course, but at these
frequencies, you can fabricate a LOT of elements for low cost because they're
small. Perhaps even chip-scale integration is possible. $1/element is feasible
for phased arrays.

~~~
mNovak
The antennas are practically free; the cost comes from phase shifters,
amplifiers, etc, which don't see much miniaturization benefit at high
frequencies. One day $1 per element is feasible, but definitely not today.

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danesparza
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.

~~~
madengr
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...](https://www.everythingrf.com/rf-calculators/effective-antenna-
aperture-calculator)

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ldite
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...](https://www.siversima.com/wp-
content/uploads/product-brief-trx-bf01-20200220.pdf)

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tus88
How does that work when no Silicon runs at 60ghz? What can process the signal?

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tomxor
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).

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creatornator
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

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tomxor
> 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.

Ah, this is not what I meant but just as relevant. I think you are essentially
saying that you don't have to send as many bits per second that the signal
frequency is capable of? I suppose that would satisfy any arguments that focus
on bit throughput.

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richk449
Is this just a passive phased array? I can’t electronically steer it, can I?

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

[https://perasotech.com/x-series-products/](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.

~~~
richk449
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)?

~~~
madengr
Yes. Each PA probably has no more that 10 mW (assuming CMOS), but coherently
added will yield over 100 mW EIRP. For RX the signal coherently adds, but the
LNA for each channel has uncorrelated noise, so the RX SNR is not as good as a
passive array (assuming zero feed loss). Probably other circuitry to keep all
the channels calibrated.

No, not in that chip. It has differential I & Q baseband I/O which are split
and converted using a LO coherent to all the channels, then amplitude and
phase shifted.

No, that would require phase and amplitude weighting to be done at digital
baseband. There are some other ICs with 4 channels to drive 4 element sub-
arrays. These large MIMO arrays will have sub-arrays with RF amplitude and
phase weighting, then each sub-array is fed with I & Q baseband with separate
weighting.

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dillonmckay
Is 60GHz band unlicensed in US and EU?

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monocasa
Not in the US at least.

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walrus01
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.

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jotm
I believe that's what he meant, _not [licensed] in the US at least_.

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hestefisk
That’s Hz, isn’t it?

