Single-Side-Band Techniques at Microwave Bands, Chapter 10
@ OK1AIY
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The first experiments in 122 GHz Band
The 122 GHz band is a new one as related to other bands. Vienna IARU
conference of 28-29 Feb.2004 had „mixed“ the cards with some substantial
changes. The 145 band was terminated and in other bands the frequencies were
changed. Two new bands were introduced, 122 and 134 GHz as can be seen in
Table 4. The following Table 5 shows the 122 GHz band frequency plan starting
at 122.250 GHz where SSB and CW operation is concentrated.
As the frequency shift from the original 145 GHz band was not too significant
(23 GHz only), the original transverter was considered for a redesign. (But it
was already modified for experiments at 245 GHz as mentioned later in the
text). For the first experiments it was not a good idea to develop completely
new transverters, so the existing modules were modified. This called for new
oscillator crystals, and retuning the „multiplier blocks“ MKU 12LO from DB6NT
which seemed to be not too successful. It was finally done with a lower output
power. Other components could be used without modifications, even the
waveguide (a stainless steel capillary tube, 1.5 mm dia.) was usable. The
block diagram is shown in Fig. 387. A practical versions on tripods ready for
testing are shown in Fig. 388. A reader might see the above talk as a „fairy
tale“, but it had a lot of tough work in it. We lacked any suitable
instrumentation, of course, but the experience of 145 GHz band systems was
useful as well as that from lower bands. The procedure follows the same
pattern : accurate frequencies to be measured, and multiplication works all
the time. The most important is a careful adjustment in a workshop, testing
the communication between the tables, and then we can try a longer distance
outdoors, Fig.389.
The described transverter by DB6NT is the simplest version, with an output
power measured in micro-Watts, so no DX can be achieved. One of the obstacles
is the water vapor content in air. The better propagation can be expected in a
clear dry weather when water vapor has condensed, so the propagation loss is
lower. When we did the first test by 2.8.2006, the conditions were not optimal
but the SSB QSO over several hundred meters was wonderfully good. A next step
was taken over 1.2 km distance but then only CW mode worked.
Table 4 Frequency plan after Vienna IARU conference, 2004
Table 5 122 GHz Frequency Plan
Fig. 387 Block diagram of the 122 GHz Transverter, 1st generation
Fig.388 122 GHz Equipment of 1st generation
Fig.389 First tests at 122 GHz. As an alkaline battery can be seen, the time
was long ago
Other Transverters for 122 GHz Band
In the mentioned period, also OK1EM and OK1JHM have built their 122 GHz
transverters , 1st generation. (Figs. 392 and 393). During 2006-2008, Philipp,
DL2AM has worked on a new transverter version. As the „progress cannot be
stopped“ and new components became available, he was successful. New diodes
for mixers and multipliers could be used, also a professional multiplier,
CMA382400AUP for 3 and 4 times, allowing to generate up to 100 mW power around
40 GHz. DL2AM has devoted a large effort in the development, he could use good
instrumentation, so his new transverter he described in CQ-DL magazine could
generate tens of micro-Watts with SSB, and as a CW beacon for testing, up to
0.5-1.0 mW.
In this time period, also Aleš, OK1FPC entered the new design by a
professional approach, Fig. 394. He purchased the necessary diodes (not a
simple action), and within a training on West Pond manipulator, he could
install them in the circuit boards (I frankly admire someone who could do such
a thing on a kitchen table). The resulting circuits worked equally well like
those by DB6NT. This offered an opportunity to update older equipment for 47
and 76 GHz. More improvement was given to the beacons, OK0EA, OK0EL and SR6GHC
and SR3KHC, so more experimentation became easier. At 122 GHz , new 2nd
generation equipment appeared (Figs. 395...398), and thanks to DF9LN
oscillators built by OK1UFL, also the frequency stability was good. This time
was perceived as the happiest one due to the collective effort leading to good
results. Communication was only possible over shorter distances, so the
„Contest QSOs“ were only achieved to the „next square“. Our new designs of the
2nd generation had a „beacon“ signal source mounted next to the transceiver on
a tripod, with their antennas aligned. This idea by OK1UFL allows a precise
pointing of a receive antenna to the stronger beacon signal, then the SSB
operation was easier to achieve.
More details are given in the description of 76 GHz designs. We used this nice
method with OK1UFL between Benecko and Kozákov, 22 km, by 26.9.2009, Figs. 399,
400.
Fig.392 Eda, OK1EM, during a contest. A nice weather is needed for a succesful
operation.
Fig.393 Transverter by OK1JHM for 122 GHz, 1st generation
Fig.394 Aleš, OK1FPC, in his workshop, 2007
Fig.395 Transverter by OK1EM for 122 GHz band
Fig.396 Transverter by OK1EM, side view
This arrangement allows to switch the transverter to a lower band for a
precise adjustment
Fig.397 A view of OK1EM transverter for 122 GHz, from the radiator side
Fig.398 OK1EM with his equipment for 122 GHz, this time the weather failed to
cooperate
Fig.399 OK1UFL, 26.9.2009 QSO between Kozákov and Benecko on 122 GHz. On the
right side, there was a 47 GHz transceiver for a coarse pointing and as a
walkie-talkie
Fig.400 QTH Kozákov, 26.9.2009. The weather was not favorable for 122 GHz,
high air humidity
The 122 GHz band and our Polish neighbors (SP6 exactly)
Also in our Polish neighborhood there was a growing number of 122 GHz
equipment. Fig.401 shows three systems tested during our meeting at Three
Wells (Tri studny) in 2009. Standa, SP6BTV (Fig.402) took an apprenticeship at
OK1UFL in Jilemnice where 122 GHz transverters were gradually put to life,
recognized all possible problems, then organized his whole family to develop
his equipment. He organized expeditions to locations suitable to communicate
with neighboring states: he contacted some local hams for help, and even
loaned his equipment if the party lacked one.
One successful expeditions happened in August 2008, one year earlier, then
only on 24, 47 and 76 GHz, among Poland, Slovakia and the Czech Republic. From
OK the participant was Míla, OK1UFL. The expedition was well documented, so it
is worth of mentioning it here. The parties chose a strategic location where
three borders joined, and included a meeting with local OMs who had weekend
cabins there (Fig.403). Fig.404 shows that several first QSOs were made. The
meeting was quite cordial, and they celebrated it joyfully as shown in
Fig.405. Standa SP6BTV was a good friend, a perfect organizer and enthusiast.
Unfortunately, he passed away abruptly, and the activities ceased.
Fig. 401 Three new systems for 122 GHz at Tri Studny meeting, 2009.
Fig.402 Standa, SP6BTV, in operation, (SK May 2009).
Fig.403 A friendly meeting at a cabin of OM6TX
Fig. 404 The tactical QTH suitable for microwave communication among three
countries
Fig. 405 Standa would not forget anything: He prepared a detailed itinerary
and a memorial plaque
Radio Amateur 122 GHz Band , activities in Moravia
In 2007 the experienced Moravian designers of 47 and 76 GHz entered their
activity at 122 GHz. Milan, OK2MH, had attended DL2AM's workshop, and he even
loaned him one transverter for experiments. At the same time, Pavel, OK2VJC,
and Peter, OK2ULQ, with Eda, OK2BPR, worked on the new transverters (Figs.406,
407). The work was not easy but the team cooperation was good, and after a
short time the systems came to life at the workshop and then short-distance
was covered outdoors (Fig.408...412). By gradual improvement, the distances
grew and the transceivers were qualified for a contest. In October 2008 during
the UHF Contest, they made a QSO with OK2KYC over 4.8 km (Fig.413). As
Slovakia is not far away, the first international QSO was foreseen.
The first QSO with a new state is always a celebrated event for the actors (at
any band), so a suitable path was sought to make it possible. Direct line of
sight was essential, and also an accessibility of locations by cars. After
some time the locations were found and by 18.8.2009 the first QSO was made
between OK2IMH/p and OM/OK2VJC/p over 3 km.
Fig.406 A 122 GHz dish at OK2VJC transverter
Fig.407 122 GHz, a detailed view of transverter in dish focus, OK2VJC
Fig.408 Tens of hours of testing at OK2ULQ OK2VJC and OK2IMH
Fig.409 A testing day at OK2VJC's garden, Peter OK2ULQ stands next to the
transverter
Fig.410 OK2IMH at his workshop
Fig.411 Left to right, OK2VJC, OK2ULQ
Fig.412 Eda, OK2BPR (SK2020) pointing the 122 GHz dish
Fig.413 UHF Contest 2008, Zdeněk, OK2BUC, for OK2KYC communicating with OK2VJC
over 4.8 km
Figs, 414, 415 and 416 present the first OK-OM QSO in the microwave band of
122 GHz, made by 18 August, 2009. OK2IMH described it in detail at:
From our experience we know that such suitable location is often difficult to
find. Then the only option can be to make the QSO over the official border
check point or close to it. The positive aspect is that the border crossing is
on a road, so we can come by a car. Strict DX hams might be annoyed but as the
EHF equipment may be not yet finished in development and the power minuscule,
such may be the only option.
The first QSO stimulated more improvement of the three functional systems. New
components became available for this step. These were MKU LO 8-13 oscillators
from DB6NT (Fig.417), installed in a nice box (Fig.418) . And later in 2019
more nice finished products, the „Bodnar“ oscillators controlled by GPS. These
oscillators offered the precise and stable operation frequency and made for an
easier experimentation. The GPS-controlled BODNAR oscillators can be
programmed for output frequency over 400 Hz to 810 Mhz, and output power can
be set in three ranges, from 6 to 20 mW. The GPS receiver is included with a
magnet to attach to a suitable surface. It usually functions indoors close to
a window, to „see“ some satellites in the sky. It is shown in Fig.419, and a
view into the „magic box“ is in Fig.420. More detailed information can be
found at:
Fig. 414 Pavel, OK2VJC, during the first OK-OM QSO at 122 GHz
Fig.415 The arrow points to the QTH of OM/OK2VJC/p
Fig.416 The QTH of Milan, OM2IMH/p
Fig.417 122 GHz band: Mounting of MKU-LO8-13 PLL oscillator by DB6NT
Fig.418 Oscillator 8-13 GHz in a box, on the right, a 10 MHZ input connector
from GPS
Fig.419 The BODNAR programmable GPS-controlled oscillator (400 Hz to 840 Mhz)
Fig.420 A programmable GPS-controlled oscillator by Leo Bodnar (a view on the
PCB)
Two active stations taking part in all contests are a father-and-son team,
OK2QI and OK2LL (Fig.421). They use substantial parts in transceivers by
OK1FPC, one antenna is from OK1EM, and mounting in suitable enclosures is
shown in Figs. 422,423. The beacon as a necessary device is shown in Fig. 424.
The distance from the Praděd summit where OK2QI rents his QTH/p, to Jeseník
city where he has a permanent QTH, is too far even for 76 GHz band. Therefore
their contest QSOs are made over 2 km, OK2LL moves to a parking lot in Ovčárna
pod Pradědem. Fig.425 shows Luboš, OK2LL, with one of his transceivers.
The technology advances quite fast, and a next novelty is here: the
professional radar modules for motor vehicles to enable them riding without
drivers. A kit by VK3CV operates at 122 GHz with CW and FM modes, with about
0.5 mW output power. Inside of a miniature chip there are a phase-lock circuit,
a twin antenna systém, and a RX preamplifier. Such components are by now in
hands of hundreds of designers around the world, and they discuss design
details on the internet. In the Czech Republic we have several functioning
systems, after tests some first results, we will present them in next parts of
our series. This is a next step forward. More details can be found on OK1EM
website.
Fig. 421 Equipment od OK2QI and OK2LL for 122 GHz:
Fig. 422 Transverter by OK2LL, front view
Fig.423 A rear view on the transverter by OK2LL
Fig.424 The beacon is a necessary device for experiments in a workshop
Fig.425 Luboš Loos, OK2LL, the son of František, OK2QI
122 GHz band, VK3CV design
The reader may perceive this series a a „historic work“. I do not think of it
as too historic when we present designs and events only years or months old.
It is true that the progress advances very fast. What happened in the eyes of
the community as far away in time, we try to compare it with the really tens
of years ago when we had few good components and instruments, and radio
amateurs had to create and manufacture most of instruments on a „mass“ scale.
The question is what we can use in today's designs with the available low-cost
new parts, often ready to use. The answer is yes, it can save time and effort.
One good example is the „world-wide“ action, the transceiver design described
by VK3CV , with a professional chip made for the auto industry, Figs. 430,
431.
There is a discussion forum running on the internet, where the designers can
share their experience:
Also on OK1EM's website there are more informations:
The current action brings a hope in good results which are sure to come by in
the collective effort, a hope to achieve longer QSOs in this demanding new
band, and move the progress forward.
Figures 426...429 present the new transverter for 122 GHz by OK1UFL, 3rd
generation, with the TRX 120 radar chip (Figs. 430,431), mentioned above in
the earlier part of our series. The development required a suitable workshop
instrumentation, good eyes and „sure hand“ skills. (I have not taken part in
this collective action myself, I would rather wait for some future versions...)
Fig.426 Equipment for 122 GHz band by OK1UFL made after VK3CV. In the rear,
Žalý summit, and on the right on horizon, Černá Hora.
Fig. 427 Another view on OK1UFL system.
Fig. 428 Míla, OK1UFL, with his equipment for 122 GHz, made after VK3CV. Front
view at JO70SP locator.
Fig.429 A view on the transverter, also GPS antenna and power supply can be
seen.
Fig.430 TRX12 chip
Fig.431 TRX 120 block diagram
For the first testing, not everybody would have access to suitable
instrumentation, so the usual method can be used again: listening for the
signal by another systém. Then we can hear the „finest nuances“ than cannot be
detected by a spectrum analyzer or a SDR receiver at the IF level. We did it
this way with Míla, OK1UFL, in 2006 at the very beginning, and later in 2008
when the 2nd generation of the equipment was ready. The original one was used
as a „tester“.
Sunday 25 October 2020 was one of last fall days with a good weather, so we
arranged a small „testing day“. We started over a short range as seen in Fig.
432. OK1UFL had his equipment adjusted in his workshop,, both signal
frequencies agreed accurately, and the signals were strong. Over a longer
distance, 600 meters, Fig. 433, we adjusted all elements than cannot be preset
in a workshop, like antenna alignment, telescope, etc. Contrary to a contest
situation when there is no time for experiments, we had enough time to also
test a second equipment, the „tester“. As it was already „aged“, I added the
GPS control before the Field Day (Figs. 434,435). From practical reasons the
control can be switched (on GPS, off GPS), to tell the difference. A
difference was observed even though that the oscillators of DF9LN made by
OK1UFL have been fully adequate..
The test by fire the transverter underwent by 26.5.2012 during the first QSO
OK-OE, over 26 km, which as was later determined was not along the line of
sight. Details can be seen on our pages here as well as on OK2KKW web pages.:
Fig.432 Tests in Horní Štěpánice (JO70SP) over a short distance at 122 GHz
Fig. 433 A telescope view of the opposite station, OK1UFL equipment
Figs. 434,435 Two views on OK1AIY equipment for 122 GHz, with BODNAR
oscillator, and switchable to the original version, (Field Day 2020).
Figs.436,437 Microwaves in the U.S.A.. Mike, K6ML on the left, Randy's
equipment, KI6TWT on the right, (www.50mhzandup.org).
This paper was also published in print in Practical Eectronics magazine, with
permissione (PE/AR Magazine – Practical Electronic and Amateur Radio, Czech
amateur magazine, in Czech).
Related links:
Česká verze