[NLRS] 122 GHz Band and equipment (LONG)

Tue Oct 8 17:00:40 EDT 2019

Yes... 122 GHZ !

This may not be of interest to many (most ?) of you, but there may be some interest.

We have a band at 122GHz AND there are some commercial parts available for it.  Its also 
an ISM band and there are automotive collision avoidance radars up there.  The parts are 
basically complete systems on a single chip so the only signals OFF chip are i.f. 
frequencies, control data streams and DC power.  Mike Lavelle, K6ML, has built a system 
and Tim, VK2XAX has a similar but slightly different version in process.

Tim is having his system manufactured and offering it as a built and tested board: ~ 
144MHZ in, 122GHz out. The board and Chaparral horn for dish feed (TVRO-style) will be 
available for ~ US$300 +shipping from Australia.  Some  mechanical work, plus a GPSDO (or 
a VERY good OCXO) will be required to make the system work.

NOTE:  I had a note from Tim on 29 Sept saying that the $300 price was based on a "buy" of 
10 units.  As of then, he had more than 100 pre-orders and expects the price to drop (but 
he doesn't know how much yet).

I'm cut & pasting K6ML's posting re: the project as it has pointers to documentation for 
the project.

Doug, AD0CX,  and I planning on ordering systems and there have 3 others "interested" but 
not committed.  We have at5 least a couple of weeks before a hard commit is need (and 
money).  If there is further interest, please e-mail me and I'll get you on the list.

122GHz is decidedly an "exotic."  There are both moisture- and oxygen- absorption losses 
to contend with as well as VERY narrow beam-widths from the dish antennas.  (~50dB ! gain 
on a 24" dish means ~0.5° BW)  The VK stations have been getting 50-60 km ranges.  We get 
low humidity in winter; that helps.  We're not at sea level, so there is 'some' lower 
oxygen content, but not much.  MAYBE the evaporation duct on Superior would help ?

Again, let me know within the next week or two (tops) if you think you'd be interested.

73 Donn
WA2VOI/0

********
Below is the cut & paste from K6ML's e-mail.

> >     FYI, Andrew (VK3CV) has just published (in DUBUS magazine) a second 122 GHz radio 
> > design based on a Silicon Radar chip 
> > (https://siliconradar.com/products/#120ghz-radar-chips).  The email below contains a 
> > pointer to the article along with construction details.
> >
> >
> >     Tim (VK2XAX) is organizing a group buy of assembled PCBs and machined horns based 
> > on Andrew's design.  He's asking who might want to sign up for the buy (in the next 
> > few weeks).  It sounds like it will be at least 3 months till delivery.  This is an 
> > opportunity to get on the band "As Easy As 1-2-2" (the title of Andrew's paper).
> >
> >
> >     Our two designs are quite similar, but still differ.
> >
> >
> >     Andrew's more recent design uses the newer TRX_120_002 chip, ADF4153 PLL, PIC 
> > microcontroller, and a 144 MHz IF.   See below for links to his article & design info.
> >
> >
> >     My design was started a couple of years ago and is based on the first chip from 
> > Silicon Radar (TRX_120_001), ADF4159 PLL, Arduino microcontroller and a 2.5 MHz IF. 
> > See the MUD 2017 proceedings and 
> > http://www.bay-net.org/uploads/1/2/2/7/122774721/k6ml-122ghzradio-baycon2018.pdf for 
> > more info on my initial design if you're interested.
> >
> >
> >     The main difference in the two designs stems from the choice of chip and our 
> > machining skills.  While the RF specs of both chips are identical (half a milliwatt 
> > power out, 11 dB NF and separate in-package Tx and Rx antennas), the antenna designs 
> > are different.  My _001 chip has higher gain (2x2 patch array) antennas spaced 3 mm 
> > apart in a larger (8x8 mm) package while Andrew's _002 chip has lower gain (dipole) 
> > antennas spaced 1.67 mm apart in a smaller (5x5 mm) package.
> >
> >
> >     In both cases, the spacing between the in-package antennas is large enough that, 
> > when placed at the focal point of a dish reflector (for higher gain), the Tx and Rx 
> > beams will skew in two quite different directions.  Andrew's solution was to machine a 
> > combiner cap that fits over the (smaller) chip and uses the rx and tx antennas to 
> > funnel the two signals into a common circular waveguide, which then drives a single 
> > (Chaparrel style) feed horn antenna fixed at the focal point.  My solution was to make 
> > a motorized x-y stage to move my PCB during T/R switching so that the Arduino places 
> > the desired patch antenna array (in my larger chip) at the focal point.  No feed horn 
> > is needed, as the patch antenna gain is similar to a small horn.   Two different ways 
> > to skin the same cat.
> >
> >
> >     So far, Andrew has built two complete systems with 60cm dish antennas, and as of 
> > early July (dry season Down Under), his best reported DX was just under 60 km, a bit 
> > under half the current world record of 132 km.   I work more slowly, and as of our 
> > last dry season (six months earlier in this hemisphere), I only had built one dish 
> > based system, so my best DX is 25 km using a 60 cm dish on one end talking to a a bare 
> > chip (no dish) on the other end.  I expect to get comparable results later this fall, 
> > now that I'm finishing up my second dish based system and the dry weather is 
> > approaching.
> >
> >
> >     122 GHz propagation is not easy; it's very highly dependent on water vapor and 
> > oxygen absorption loss (about 1 to 2 S-units extra loss for each 10km of path length 
> > at typical humidity and sea level, see WA1ZMS's mmwave loss charts at www.wa1mba.org). 
> > The way to get DX on this band is to operate at an extremely low dew point and higher 
> > elevations, to reduce H2O and O2 losses, and on a LOS path.

****************
> >         -------- Original Message ----------
> From: "Tim VK2XAX at skybase.net [VK-Microwave]" <VK-Microwave at yahoogroups.com>
> To: VK-Microwave at yahoogroups.com, VK2-MUG <VK2-Microwave-Users-Group at groups.io>
> Date: September 16, 2019 at 11:35 PM
> Subject: [VK-Microwave] 122GHz for All !
>
>
>
> Hi all,
>
> By now many of you have received your DUBUS magazine and had a read of
> the 122GHz transverter project by Andrew, VK3CV.
>
> For those of you who went to Gippstech you will recognize the
> transverter as the one that was on display, pictures of which I took and
> have saved here...
>
> https://photos.app.goo.gl/8oi3HrveRXs7ZoSX8
>
> That includes a scan of the summary document that was handed out at the
> conference.
>
> Andrew has kindly put all the articles, documentation, schematics, etc.
> of this project on the net and made it all available from his dropbox
> here...
>
> https://www.dropbox.com/sh/32iznukohqnpjsz/AADXslP2AEr8md9e9Eg_tHEGa?dl=0
>
> For those of you who do not subscribe to DUBUS, the published article is
> this document...
>
> https://www.dropbox.com/sh/32iznukohqnpjsz/AAABv0Y5OMHjqbQWZTNozYPAa/As%20Easy%20as%20122GHz%2020_07_2019%20%28Compressed%20images%29.pdf?dl=0
>
> In the month or so since Gippstech I've been gathering quotes from
> various manufacturers to build the transverter PCB to a complete working
> state including Xray board testing, code load to PIC and functional
> tests at power-on that meets my test plan so that the units would be
> delivered to me supposedly working.
>
> I've spoken with at least 3 manufacturers and created specific
> bill-of-materials for each to utilize their in-house supply chains for
> lowest possible component cost. I'm currently in discussions with
> another to get a competitive quote from them as well. Likewise for the
> feed horn assembly. Machining costs vary markedly across those I've
> already asked.
>
> The indicative cost estimates are based on a quantity of 10 since that's
> the minimum order level for all of them. The more orders we get the
> cheaper it becomes. Machining costs for the horns drop by nearly a
> factor of 100 if I order 1000, but I think that number is a bit of
> wishful thinking at this stage. One can only hope :)
>
> Indicative pricing in $USD is and it has to be because that's what all
> the manufacturers deal in.
>
> Complete assembled and tested PCB : $204 USD
>
> Chaparral style feed horn and coupler : $72 USD
>
> Conical Horn $110 USD
>
> None of these $ values include shipping to you.
>
> I haven't got a specific quote for "board only" since I figured most
> people would want a built-and-tested board and to not have to worry
> about soldering 0603 size SMD parts and expensive IC's.
>
> That being said I've already had enquirers from the UK for boards only.
> So if someone wants a board only, I'll can take note and ask for a quote
> when I get sufficient numbers.
>
> so... have a good read of the article since there is still some
> construction to do with putting the PCB to work and if you decide you
> want one or two or more, please drop me an email and I'll add you to the
> list.
>
> After a month to let the stragglers catch up, I'll ask the manufacturers
> for an updated quote with the numbers I get and report back the $ amount
> we will actually be up for.
>
> Build & test times for the manufacturers are typically 6 to 8 weeks
> including shipping once an order is placed.
>
> So... who wants to go play on 122GHz ?
>
> regards
>
> Tim
>
> --
> VK2XAX : QF56if : ITU59 : CQ30 : BMARC : WIA
>
> ---