1. Preparations for 78 GHz EME The NEXT Final Frontier?
Barry Malowanchuk VE4MA
Microwave Update Conference
October 2010

2. Preparations for 78 GHz EME – The NEXT Final Front Frontier?
The Challenges
The Technology
Results to Date & Schedule
This presentation intends to tell the story of the first ever amateur radio 2 way communications off the moon on 47 GHz.
It will talk about the many tests conducted, the challenges encountered and overcome, the technologies used to do it and the operating results.

3. Recall the First 47 GHz Echoes
RW3BP on July 24, 2004 “Outstanding! ”
>100 Watts Output, 2.4 m Offset Dish, ~ 50 MW ERP!
~4 dB NF “HB” Preamplifier, ~10 dB Sun, 1 dB Moon Noise
Copied By AD6FP, VE4MA, VE7CLD, W5LUA
But this was as good as it got !
The first echoes received were by Sergei RW3BP, who was one of the few to have accomplished EME on 24 GHz. This was an outstanding accomplishment for anyone but considering the extraordinary resourcefulness of Sergei to make use of the technologies he had available to him.
Sergei used the same 2.4 m offset fed dish that he used on 24 GHz but actually under-illuminated the surface make use of the most accurate part of the dish’s surface area.
Sergei had the good fortune to acquire a pulse rated traveling wave tube and was able to achieve short duty CW transmit powers of up to 200 W output!
He used a “home brew” preamp to achieve a noise figure just under 4 dB and the system received approximately 10 dB of Sun noise and up to 1 dB of moon noise, all of which were the best results achieved by anyone in the group.
Within a few days of hearing his own echoes, Sergei’s signals were heard by AD6FP, VE4MA, VE7CLD and W5LUA. Considering what we know today it is remarkable that these signals were actually heard.
Playback the recording made at VE4MA of Sergei’s signal

4. 2.4 m Offset Fed Dish at RW3BP
This is Sergei’s dish mounted atop his apartment block in downtown Moscow. He uses standard TVRO style dish motors and has added a rugged support frame to hold the heavy electronics mounted at the focal point, without moving relative to or distorting the surface of the dish.
Sergei uses a method of pulsing the motors on an automatic basis to achieve a level of automatic dish movement.
You will notice the sophisticated weather proofing use to cover the electronics. This technique is used all around the world.

5. 78 GHz Feed on 2.4 m Dish at RW3BP
First Tests in 2008
1 x UMS CHA1077 Preamp with a Fundamental Mixer ~ 6.5 dB DSB NF
5.8 dB of Sun Noise
0.53 dB of Moon Noise
This is another view of Sergei’s dish but without the weatherproofing.

6. EME Challenges at 78 GHz
Rough surface of moon produces very rough sounding note – like aurora
Spreading can be several hundred Hz making the use of very narrow bandwidth IF filters impossible
Doppler shift upwards of +200 kHz on rising moon and –200kHz on setting moon
Antenna beamwidths less than half the 0.5o subtended angle of the moon
These are just to give some idea of the extra challenges associated with 47 GHz EME, that makes it significantly more demanding than at any other frequency.

7. Atmospheric Effects at 78 GHz
Unlike 24 GHz, but like 47 GHz , 78 GHz is not significantly affected by Humidity on an EME path
it is a relatively thin slice of atmosphere
Oxygen absorption is present at minimum levels
Best EME conditions occur ????
Continued from the previous slide, it refers to the fact that humidity is not a factor on this band and that the seasonal and weather variations are not significant. Having said that keeping the electronics dry…..including the parts energized at 14 kV and having them work without malfunction in the rain is a challenge of course.
We have not been able to operate enough to see if there are any periods of better “conditions”

8. Best EME Conditions at 78 GHz
Atmospheric absorption worst on horizon
Doppler shift is extreme near horizon
Tracking programs calculate very closely
Signal Spreading is more severe as moon moves to zenith
But now can be predicted using software
Continued from the previous slide, it refers to the fact that humidity is not a factor on this band and that the seasonal and weather variations are not significant. Having said that keeping the electronics dry…..including the parts energized at 14 kV and having them work without malfunction in the rain is a challenge of course.
We have not been able to operate enough to see if there are any periods of better “conditions”

9. 78 GHz System Requirements
Experience from 47 GHz work
Best Available Hardware was not Good Enough
~ 4 DB NF Preamps
m Offset Dishes (~57-60 dB Gain)
30 W output
NO Signals Heard !
Predictions Said “More System Gain Needed” (NF, Ant Gain, or TX Power)..6 dB Needed
Gary was the first one in North America to be ready to transmit back to Sergei. Gary’s 30W TWT is the standard offering for power at this frequency and uses a tube that was intended for US military communications at 44.5 GHz.,His dish is a fibreglass offset dish rated for satellite use at 14 GHz. The surface of the dish has been “wallpapered” with aluminum foil. This produced a huge improvement in performance. With this change the 1.8 m reflector appears to work very well.
The receive preamps used by Gary ( and all of except Sergei) are surplus units that are no longer available.
Transmitting tests made by Gary confirmed the prediction/suspicion that 30 W is not enough with a 1.8 m dish …recall that Sergei’s echoes were made with Watts

10. 78 GHz System Hardware: Preamps
WA1MBA Preamplifier of course
~ 3 dB NF Preamps so System NF ~3.5 dB
Gary was the first one in North America to be ready to transmit back to Sergei. Gary’s 30W TWT is the standard offering for power at this frequency and uses a tube that was intended for US military communications at 44.5 GHz.,His dish is a fibreglass offset dish rated for satellite use at 14 GHz. The surface of the dish has been “wallpapered” with aluminum foil. This produced a huge improvement in performance. With this change the 1.8 m reflector appears to work very well.
The receive preamps used by Gary ( and all of except Sergei) are surplus units that are no longer available.
Transmitting tests made by Gary confirmed the prediction/suspicion that 30 W is not enough with a 1.8 m dish …recall that Sergei’s echoes were made with Watts

11. 78 GHz EME RX Improvement?
RW3BP Software “Extends The Receive Threshold”
Signal Spread from 300 to 450 Hz Wide
Long Transmission Periods
CW Transmission
BFSK & “Special” CW Modulation
Time Averaging Techniques to Extend Minimum RX Threshold
CW Playback of Averaged Signal
Newer Software JT4???
We discussed the possible use of software programs such as JT65 to achieve the required receive performance improvements. Unfortunately these programs are not suited to the operating conditions experienced on 47 GHz.
Attempts were made to get special versions of the available software routines made, but the level of support for the existing users precluded making a special version.
Sergei and a friend set out to create their own software, using CW transmissions and the fundamentals of repeating the same message over and over again over a long period to achieve a reduction in the receive noise level.
Unlike other software the reception still requires human decoding of the playback waveform.
As with all software there were several versions tested with improvements made in each version.

12. mmWave EME Software
This is the user interface screen for Sergei’s software. The messages that are sent are the minimum required…”without frills” like DE, in order to maximize the improvement of the averaging and minimize the transmit times.
A standard 10 minute transmit period was agreed upon. The modulation scheme used is BFSK with a 900 Hz shift for the NA stations. This takes advantage of the energy in the key up and key down states and gives a little further improvement.
Sergei’s TWT does not like key down operation, so that a low duty cycle CW mode was created to maximize the life of Sergei’s tube.
The present software allows the setting of the receive bandwidth of the FFT spectrum analyzer windows and the CW speed. This should make the software of great value at the lower microwave frequencies and give the big improvements see through the use of software on the low frequencies.
There are still (it seems) some issues with the variation between clocks on the sound cards but this is being worked on.
The program is not in its present form setup for random QSOs. It would require the definition of standard message lengths, with the ability to accommodate the longest sets of calls. This will reduce the improvement, but for scheduled operation this should not be an issue.
Notice the illuminated square “LEDs” that in this case signify that there is energy at 1150 Hz and then some energy 900 Hz higher. Clicking on the brightest LED allows play back of the recovered CW waveform, even as it is still averaging the incoming signal.
Also note the oscilloscope like display of the recovered waveform.
Playback the recovered signal of VE4MA as received by AD6FP at a S/N level of dB. Although the waveform is still somewhat distorted, this is a HUGE improvement on the wisps of signal heard earlier from RW3BP

13. Better RX Performance With Cooling?
This was Gary’s test setup with the preamp enclosed in a modified vacuum bottle sealed with a foam lid.

14. Better 47 GHz RX Performance With Liquid Nitrogen Cooling?
deg K (4 290 K)
This is a closeup of the vacuum bottle. You can see the input/ output waveguides and power cable. The performance with liquid nitrogen improved from approximately 4 dB NF to less than 1.5 dB.
This achievement was very exciting and probably practical for the preamps in NA, but Not for Sergei, whose silver epoxy connections are unlikely to survive.
For the first QSOs to occur, Sergei needed to see the improvement at his end on receive.

15. 78 GHz System Hardware: Preamps
Preamps will not withstand LN2….but Dry Ice?
Noise Figure of RX Mixer still needs to be Very Good ~6 dB SSB
Standard Subharmonic Mixer ~13 dB NF , so must use Fundamental mixer
Gary was the first one in North America to be ready to transmit back to Sergei. Gary’s 30W TWT is the standard offering for power at this frequency and uses a tube that was intended for US military communications at 44.5 GHz.,His dish is a fibreglass offset dish rated for satellite use at 14 GHz. The surface of the dish has been “wallpapered” with aluminum foil. This produced a huge improvement in performance. With this change the 1.8 m reflector appears to work very well.
The receive preamps used by Gary ( and all of except Sergei) are surplus units that are no longer available.
Transmitting tests made by Gary confirmed the prediction/suspicion that 30 W is not enough with a 1.8 m dish …recall that Sergei’s echoes were made with Watts

16. 78 GHz System Hardware: Antennas
2.4m dishes were Marginal at 47 GHz
1.8m dish of AD6FP provided best performance
Test Big and Small Dishes at 78 GHz
Even 1m dish has ~57 dB gain and 0.5 deg BW
Perfect 2.4 m dish has 63 dB gain & 0.11 BW
The moon is only 0.5 degrees wide
Gary was the first one in North America to be ready to transmit back to Sergei. Gary’s 30W TWT is the standard offering for power at this frequency and uses a tube that was intended for US military communications at 44.5 GHz.,His dish is a fibreglass offset dish rated for satellite use at 14 GHz. The surface of the dish has been “wallpapered” with aluminum foil. This produced a huge improvement in performance. With this change the 1.8 m reflector appears to work very well.
The receive preamps used by Gary ( and all of except Sergei) are surplus units that are no longer available.
Transmitting tests made by Gary confirmed the prediction/suspicion that 30 W is not enough with a 1.8 m dish …recall that Sergei’s echoes were made with Watts

17. AD6FP 47 GHz 1.8 Meter Dish
This is Gary’s dish and you can see that the whole dish mount is mounted atop an az/ el mount. The electronics are mounted on a platform extended out from the mount and connected to the feedpoint with waveguide.

18. 78 GHz Dish Tests at W5LUA Tests on 2.4 m & 1m Dishes
Best Results from a 1m TV mini-dish
7 dB Sun Noise, 0.75 dB Moon Noise
50 Ohm/ Cold Sky 1.2 dB Ta = 133K
Still Room to Optimize
This happy fellow is W5LUA who has just completed his first 47 GHz EME QSO with RW3BP. You will note that the same sophisticated weather proof methods are used in Texas as is used in Moscow, however these bags are Texas sized!

19. 78 GHz Dish Tests at VE4MA
Better results from a 2.4m TV dish than W5LUA, but only have 6.1 dB NF so far
3.5 dB Sun Noise on 2.4m
Only 2.8 dB on 33 inch mini-dish mounted like W5LUA
This happy fellow is W5LUA who has just completed his first 47 GHz EME QSO with RW3BP. You will note that the same sophisticated weather proof methods are used in Texas as is used in Moscow, however these bags are Texas sized!

20. 78 GHz Dish Tests at VE4MA Best Results from a 1.2m Satellite dish
4.8 dB Sun Noise, still 6.1 dB NF
Dish was old Hughes DirecWay “KA” dish with aluminum foil added
This happy fellow is W5LUA who has just completed his first 47 GHz EME QSO with RW3BP. You will note that the same sophisticated weather proof methods are used in Texas as is used in Moscow, however these bags are Texas sized!

21. 78 GHz System Hardware: Transmitter
In 2008 we said 100 W tubes on market , but custom built and cost of about $100K….so unlike available to amateurs
Gary was the first one in North America to be ready to transmit back to Sergei. Gary’s 30W TWT is the standard offering for power at this frequency and uses a tube that was intended for US military communications at 44.5 GHz.,His dish is a fibreglass offset dish rated for satellite use at 14 GHz. The surface of the dish has been “wallpapered” with aluminum foil. This produced a huge improvement in performance. With this change the 1.8 m reflector appears to work very well.
The receive preamps used by Gary ( and all of except Sergei) are surplus units that are no longer available.
Transmitting tests made by Gary confirmed the prediction/suspicion that 30 W is not enough with a 1.8 m dish …recall that Sergei’s echoes were made with Watts

22. 78 GHz System Hardware: Transmitter
“I WON the LOTTERY !”
73 Watt Klystron Oscillator
Tested on MHz +/- 82 MHz
This Tube was One of Four
The Search Continues for a Companion Tube
Gary was the first one in North America to be ready to transmit back to Sergei. Gary’s 30W TWT is the standard offering for power at this frequency and uses a tube that was intended for US military communications at 44.5 GHz.,His dish is a fibreglass offset dish rated for satellite use at 14 GHz. The surface of the dish has been “wallpapered” with aluminum foil. This produced a huge improvement in performance. With this change the 1.8 m reflector appears to work very well.
The receive preamps used by Gary ( and all of except Sergei) are surplus units that are no longer available.
Transmitting tests made by Gary confirmed the prediction/suspicion that 30 W is not enough with a 1.8 m dish …recall that Sergei’s echoes were made with Watts

23. 78 GHz System Hardware: Transmitter
Needs 9 kV Power Supply and Really Good Water Cooling system
Have HV Extension Cable
Water Cooling in Sub Freezing Temperatures?
Will need to be Phase Locked and FSK’d for Modulation
Gary was the first one in North America to be ready to transmit back to Sergei. Gary’s 30W TWT is the standard offering for power at this frequency and uses a tube that was intended for US military communications at 44.5 GHz.,His dish is a fibreglass offset dish rated for satellite use at 14 GHz. The surface of the dish has been “wallpapered” with aluminum foil. This produced a huge improvement in performance. With this change the 1.8 m reflector appears to work very well.
The receive preamps used by Gary ( and all of except Sergei) are surplus units that are no longer available.
Transmitting tests made by Gary confirmed the prediction/suspicion that 30 W is not enough with a 1.8 m dish …recall that Sergei’s echoes were made with Watts

24. RW3BP Software Technical Requirements
Hold Frequency Within 200 Hz for 10 Min
Need to Correct for Doppler ….Exactly and correct at ~700 Hz / minute
Phase Locking Simple Now?
Use Reflock or ??…Simple Plug & Play??
Need Interface to HVPS for Phase Lock
In order to use the new software the frequency of the microwave local oscillators must be extremely stable ( within 100 Hz) over periods longer than 10 minutes. This is basically impossible without phase locking to a super stable reference such as GPS satellites. Both RW3BP and AD6FP created this feature in their stations right from the beginning, whileW5LUA and VE4MA had to add this later.
Now with modern phase locking this should have been easy. Attempts were made to use the Reflock board and it was found that reasonable performance could not be obtained without considerable experimentation with the PLL loop filter component values.

25. Varian 13 kV Power Supply Mods
This is the HV power supply at VE4MA and is the one used for the original 24 GHz EME work.

26. (2006) The First 80 GHz EME QSO ? 80 GHz Will Be MORE Difficult !
CPI Canada makes 80 W Tubes ~$100K!
5 dB NF Preamplifier Chips Available
Dish Performance Questionable?
80 GHz EME QSOs….Unlikely
Now with all of the challenges having been overcome, the first QSOs have been completed. The moon window is relatively short for everyone to participate.
Additional tests are being scheduled.
The work to make things better continues

27. The First 78 GHz EME Work? Echoes within a year ???
Have 1 Tube …need second one for a QSO
Or can we send one Tube back and forth???
Good Dish Preamp & Dish Performance
Stations working toward 78 GHz EME , RW3BP, VE4MA & W5LUA
Lots of Work Still Required to Make it Happen!
This slide summarizes the situation with the 4 stations actively working together to make the first QSOs happen but facing a technology brick wall.

28. Preparations for 78 GHz EME – The NEXT Final Front Frontier?
The Challenges
The Technology
Results to Date & Schedule
Questions ???
This presentation intends to tell the story of the first ever amateur radio 2 way communications off the moon on 47 GHz.
It will talk about the many tests conducted, the challenges encountered and overcome, the technologies used to do it and the operating results.