Presentation is loading. Please wait.

Presentation is loading. Please wait.

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

Similar presentations


Presentation on theme: "1 Radio amateurs and Microwaves An overview of –Basic principles –Techniques used –Activities –Results This is an invitation to join the microwave activities."— Presentation transcript:

1

2 1 Radio amateurs and Microwaves An overview of –Basic principles –Techniques used –Activities –Results This is an invitation to join the microwave activities !!

3 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,...

4 3 Everybody says Microwaves are –Difficult –No activity –Very specialized –Home made equipment needed –Etc… But our motto is: Microwave are …. Fun! LOOK FURTHER

5 4 Signal strength The power received can be calculated with the formula of Friis: WIKIPEDIA: Conclusion: The power received decreases at higher frequencies, but……

6 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!!

7 6 Noise

8 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

9 8 Atmospheric absorption <10GHz the absorption is neglect- able >10GHz absorption becomes significant

10 9 Graphical presentation of atmospheric absorption * 100 KM

11 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

12 11 Some considerations about components De dimensions of components have big influences at microwaves –Classical Rs, Cs, PCBs 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)..

13 12 Microwave transverter setup Transmit mixer Transmit amplifiers Antenna relay Antenna Receive amplifiers (very) stable X-tal oscillator Frequency multiplier To transceiver 2 m, 70 cm receive mixer

14 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

15 14 23 cm modules examples DB6NT transverter 30 Watt power amplifier with Toshiba modules Pre amplifier Nf < 1dB 150 Watt power amplifier

16 15 23 cm Antennas yagi Loop yagi 2 meter dish

17 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 (…?...)

18 17 Technical parts of 13 cm contest station ON4SHF 13 cm transverter DB6NT Transverter Power amplifier 80 Watts out (GSM tuned to 13cm) Medium power amplifier Antenna relais and sequencer Other example of GSM amplifier

19 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

20 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

21 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

22 21 Box with transverter Dish 48 cm 10 GHz station example

23 22 Pre- amplifier Oscillator 2.5 GHz Power amplifier 4 Watt Transverter DB6NT 2m -> 3 cm Transition coax to waveguide Medium power amplifier Antenna relay Waveguide to antenna

24 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:

25 24 24 GHz components Antenna relay Toshiba 24 GHz amplifier DB6NT X-tal Oscillator 24 GHz station components Exciter 2m – 24 GHz

26 25 Examples of 24 GHz stations

27 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)WWW.ON4KST.COM

28 27 10 MHz frequency standard

29 28 In the box 10 MHZ PLL GPS RX Display processor

30 29 LO PLL

31 30 LO driver for microwave frequencies G8ACE OCXO LO PLL MHz out Locking the OCXOs to the 10 MHz frequency standard

32 31 Microwave activities Contests 4 times a year –March, May, July & October Activity days –In France, in UK, NAC (SM, LA,..) Special activities –E.g. Ysselmeer contest

33 32 Contests – the ON4SHF sites

34 33 Contests – the ON4SHF antennas

35 34 Contests – the ON4SHF operators

36 35 Activity days - ON4SHF/P

37 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!?)

38 37 Microwaving in the US (2) Rover example –W3IY/R shack in a van –50,144, 432,903,1296, 2304, 3564, 5760, 10368, 24192, –1000Qs/contest m cm 12-6mm

39 38 Thatss all JOIN THE CLUB It is question time on4cdu, on4iy

40 39 Back-up slides

41 40 Detailed Photos 10 GHz station Transverter DB6NT 2m -> 3 cm 10 GHz Pre-amplifier

42 41 Attenuation at 24 GHz

43 42 Beacon 10 GHz beacon ON0KUL/B


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

Similar presentations


Ads by Google