Presentation on theme: "Radio amateurs and Microwaves"— Presentation transcript:
1 Radio amateurs and Microwaves An overview ofBasic principlesTechniques usedActivitiesResultsThis 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 frequencies23 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 saysMicrowaves areDifficultNo activityVery specializedHome made equipment neededEtc…But our motto is: Microwave are …. Fun!LOOK FURTHER
4 Signal strengthThe 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 dimensionsAssume 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 noiseB: galactic noiseC: Galactic noise (to galactic centre with narrow beamwith)D : quiet sunE: sky noise due to oxygen and water vapourF: black body (cosmic background) 2.7 K
7 Microwave Propagation TroposphereGood location is an advantageHigh 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 significantAtmospheric absorption
9 Graphical presentation of atmospheric absorption Different graphsReference attenuation at 1 GHz1296 MHz2320 MHz10 GHz24 GHz much more attenuation!* 100 KM
10 RainscatterAntennas become efficient when their dimensions are in the same range as the wavelengthWater is polarisedRaindrops dimensions are typical 2-3mmAt 10GHz raindrops are (small) antennas which relay the incoming signalsDoppler ! Caused by random (wind) movement of the ‘antennas’.ExamplesUSA DX is 1015 km 8/2005
11 Some considerations about components De dimensions of “components” have big influences at microwavesClassical 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)..
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/SSBATV, FM relays stations: FMTypical contest ODX ~ 750Km
14 30 Watt power amplifier with Toshiba modules 23 cm modules examplesDB6NT transverterPre amplifierNf < 1dB30 Watt power amplifier with Toshiba modules150 Watt power amplifier
16 13 cm Behavior is comparable with 23 cm Transverters (E.g. DB6NT design) are frequently usedNot a lot of activity outside the contestsDX-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 DB6NTMedium power amplifierTransverterPower amplifier 80 Watts out (GSM tuned to 13cm)Antenna relais and sequencerOther example of GSM amplifier
18 6 cm Amateur band “in between” 23 cm en 3 cm One hand 13 cm tropo behaviorOther hand rain scatter possibilitiesTransverters are commonly used (E.g. DB6NT kits)Low activity on this band; in practice only activity during contestsDX ~ 600 Km2 examples
19 10 GHz Popular microwave band with reasonable amount of activity CW/SSB mode is used for DX-ingATV uses FM modulationPropagation10 GHz is the highest frequency band which does not suffer from atmospheric absorptionTroposferic ducting frequently possibleRain & Aircraft scatter possibleContest and activity day distances: > 500 KmEuropean record 1400 km
20 10 GHz technicsThe “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 exampleDish 48 cmBox with transverter
22 Transition coax to waveguide Power amplifier 4 Watt Waveguide to antennaMedium power amplifierPre-amplifierOscillator2.5 GHzAntennarelayTransverter DB6NT2m -> 3 cm
23 24 GHz“Difficult” amateur band due to absorption by water vapour ( ~0.2 dB/Km)Propagation experiments neededThe behaviour and dependencies of conditions on 24 GHz are not completely clear.Our (ON4SHF) best DX is 260 kmReasonable amount of components and equipment is available at surplus marketsExample 24 GHz QSO:
24 24 GHz station components 24 GHz components24 GHz station componentsAntenna relayToshiba 24 GHz amplifierDB6NTX-talOscillatorExciter2m – 24 GHz
26 Microwave operationsCW frequently used (but very slow is good enough ....)Site (use e.g. Radio Mobile)Weather (e.g. scatter possibilities)Frequency accuracyOCXO, GPSAntenna direction AZ/ELCalibration is important: Sun, beacons, 1st contact with known station.Talkback!!! - /PTo UK: MHz; To F: MHz; IARU EUR MHz;DXCLUSTER; CONVERS; (also via GSM/GPRS)
36 Microwaving in the US (1) Differences:More bands: 222 MHz, 903 MHz, 3.4 GHzTopography: mountain topping (East-West coast)Possibilities for coastal ducts (Nord-South at east coast, California-Hawaii at west coast)Bigger and better surplusContest rules: much advantages for mobile stations: /R suffix (to be introduced in Europe!?)
37 Microwaving in the US (2) Rover exampleW3IY/R “shack in a van”50,144, 432,903,1296, 2304, 3564, 5760, 10368, 24192, 470881000Qs/contest232706m1396-3cm90312-6mm
38 Thats’s allJOIN THE CLUBIt is question timeon4cdu, on4iy