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Radio amateurs and Microwaves

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Presentation on theme: "Radio amateurs and Microwaves"— Presentation transcript:

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


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

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