1. Radio amateurs and Microwaves
An overview of
Basic principles
Techniques used
Activities
Results
This is an invitation to join the microwave activities !!

2. Figures Microwaves are the frequencies above 1000 MHz
More than 99% of the radio amateur frequency allocation is in the microwave bands….
Amateur frequencies
23 cm, 13 cm, (9 cm not in ON), 6 cm, 3 cm (= 10 GHz), 1.2 cm (= 24 GHz)
47 & 76 GHz,...

3. But our motto is: Microwave are …. Fun!
Everybody says
Microwaves are
Difficult
No activity
Very specialized
Home made equipment needed
Etc…
But our motto is: Microwave are …. Fun!
LOOK FURTHER

4. Signal strength
The power received can be calculated with the formula of Friis:
WIKIPEDIA:
Conclusion: The power received decreases at higher frequencies,
but……
It looks like that the signals on microwaves are weaker, but

5. Signal strength with equal antennas
Formula of Friis is not “fair": at higher frequencies the dimensions of the antennas decrease!
Alternative: compare signal strength with equal antenna dimensions
Assume an antenna area of 1 m^2: the equation is now:
Conclusion: the received power increases with the frequency!!

6. Noise There is less atmospheric noise at the microwave bands
A: estimated median business man-made noise
B: galactic noise
C: Galactic noise (to galactic centre with narrow beamwith)
D : quiet sun
E: sky noise due to oxygen and water vapour
F: black body (cosmic background) 2.7 K

7. Microwave Propagation
Troposphere
Good location is an advantage
High altitude & “free horizon”
Reflection (rain & snow)
For microwave amateurs with a “bad” location rainscatter on 6 cm and on 10 & 24 GHz is an alternative

8. Atmospheric absorption
<10GHz the absorption is neglect- able
>10GHz absorption becomes significant
Atmospheric absorption

9. Graphical presentation of atmospheric absorption
Different graphs
Reference attenuation at 1 GHz
1296 MHz
2320 MHz
10 GHz
24 GHz much more attenuation!
* 100 KM

10. Rainscatter
Antennas become efficient when their dimensions are in the same range as the wavelength
Water is polarised
Raindrops dimensions are typical 2-3mm
At 10GHz raindrops are (small) antennas which relay the incoming signals
Doppler ! Caused by random (wind) movement of the ‘antennas’.
Examples
USA DX is 1015 km 8/2005

11. Some considerations about components
De dimensions of “components” have big influences at microwaves
Classical R’s, C’s, PCB’s etc. cannot be used in many places (parasitic effects)
“Special microwave” components are needed E.g. GaAs Fets, SMD components, Teflon PCBs, ....
At microwaves antennas with dimensions of several wavelengths are possible; e.g. a dish can be used.
The attenuation in coax cables can be extreme; pay attention to it and use special coax or, if possible, use waveguides (the dimensions of waveguides is at frequencies of 8 GHz and up reasonable)..

12. Microwave transverter setup
(very) stable
X-tal oscillator
Frequency multiplier
Receive amplifiers
receive mixer
Antenna
To transceiver
2 m, 70 cm
Transmit mixer
Antenna relay
Transmit amplifiers

13. 23 cm Lowest Microwave band
Transceivers for this band are available, but you can also use transverters (E.g. DB6NT)
Modes used:
DX tropo, EME: CW/SSB
ATV, FM relays stations: FM
Typical contest ODX ~ 750Km

14. 30 Watt power amplifier with Toshiba modules
23 cm modules examples
DB6NT transverter
Pre amplifier
Nf < 1dB
30 Watt power amplifier with Toshiba modules
150 Watt power amplifier

15. 23 cm Antennas
2 meter dish
yagi
Loop yagi

16. 13 cm Behavior is comparable with 23 cm
Transverters (E.g. DB6NT design) are frequently used
Not a lot of activity outside the contests
DX-ing during contests (ODX ~ 600 km)
Oscar Mode S down link…..(dead now)
ATV (…?...)

17. Technical parts of 13 cm contest station ON4SHF
13 cm transverter DB6NT
Medium power amplifier
Transverter
Power amplifier 80 Watts out (GSM tuned to 13cm)
Antenna relais and sequencer
Other example of GSM amplifier

18. 6 cm Amateur band “in between” 23 cm en 3 cm
One hand 13 cm tropo behavior
Other hand rain scatter possibilities
Transverters are commonly used (E.g. DB6NT kits)
Low activity on this band; in practice only activity during contests
DX ~ 600 Km
2 examples

19. 10 GHz Popular microwave band with reasonable amount of activity
CW/SSB mode is used for DX-ing
ATV uses FM modulation
Propagation
10 GHz is the highest frequency band which does not suffer from atmospheric absorption
Troposferic ducting frequently possible
Rain & Aircraft scatter possible
Contest and activity day distances: > 500 Km
European record 1400 km

20. 10 GHz technics
The “plumbing” time is over, a modern 10 GHz station contains PCBs with SMD components!
Building a 10 GHz station is not a project for starters, but on the other hand those who can handle SMDs is able to assemble a 10 GHz transverter PCB in a few evenings.
Tuning and testing such a PCB is not simple; the help of an experienced amateur is recommended.
Note: ‘complex’ measuring equipment is useful but not needed at all

21. 10 GHz station example
Dish 48 cm
Box with transverter

22. Transition coax to waveguide Power amplifier 4 Watt
Waveguide to antenna
Medium power amplifier
Pre-amplifier
Oscillator
2.5 GHz
Antenna
relay
Transverter DB6NT
2m -> 3 cm

23. 24 GHz
“Difficult” amateur band due to absorption by water vapour ( ~0.2 dB/Km)
Propagation experiments needed
The behaviour and dependencies of conditions on 24 GHz are not completely clear.
Our (ON4SHF) best DX is 260 km
Reasonable amount of components and equipment is available at surplus markets
Example 24 GHz QSO:

24. 24 GHz station components
24 GHz components
24 GHz station components
Antenna relay
Toshiba 24 GHz amplifier
DB6NTX-tal
Oscillator
Exciter
2m – 24 GHz

25. Examples of 24 GHz stations

26. Microwave operations
CW frequently used (but very slow is good enough ....)
Site (use e.g. Radio Mobile)
Weather (e.g. scatter possibilities)
Frequency accuracy
OCXO, GPS
Antenna direction AZ/EL
Calibration is important: Sun, beacons, 1st contact with known station.
Talkback!!! - /P
To UK: MHz; To F: MHz; IARU EUR MHz;
DXCLUSTER; CONVERS; (also via GSM/GPRS)

27. 10 MHz frequency standard

28. In the box
Display processor
10 MHZ PLL
GPS RX

29. LO PLL

30. LO driver for microwave frequencies
Locking the OCXOs to the 10 MHz frequency standard
G8ACE
OCXO LO
PLL
MHz out

31. Microwave activities Contests 4 times a year Activity days
March, May, July & October
Activity days
In France, in UK, NAC (SM, LA, ..)
Special activities
E.g. Ysselmeer contest

32. Contests – the ON4SHF sites

33. Contests – the ON4SHF antennas

34. Contests – the ON4SHF operators

35. Activity days - ON4SHF/P

36. Microwaving in the US (1)
Differences:
More bands: 222 MHz, 903 MHz, 3.4 GHz
Topography: mountain topping (East-West coast)
Possibilities for coastal ducts (Nord-South at east coast, California-Hawaii at west coast)
Bigger and better surplus
Contest rules: much advantages for mobile stations: /R suffix (to be introduced in Europe!?)

37. Microwaving in the US (2)
Rover example
W3IY/R “shack in a van”
50,144, 432,903,1296, 2304, 3564, 5760, 10368, 24192, 47088
1000Qs/contest 23 2 70 6m 13 9
6-3cm
903
12-6mm

38. Thats’s all
JOIN THE CLUB
It is question time
on4cdu, on4iy

39. Back-up slides

40. Detailed Photos 10 GHz station
Transverter DB6NT
2m -> 3 cm
10 GHz
Pre-amplifier

41. Attenuation at 24 GHz

42. Beacon
10 GHz beacon ON0KUL/B