Radio amateurs and Microwaves

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
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

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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 m2 the equation is
  now
• Conclusion the received power increases with the
  frequency!!

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Noise
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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

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Atmospheric absorption

• lt10GHz the absorption is neglect- able
• gt10GHz absorption becomes significant

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Graphical presentation of atmospheric absorption
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

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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)..

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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

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23 cm modules examples
DB6NT transverter
Pre amplifier Nf lt 1dB
30 Watt power amplifier with Toshiba modules
150 Watt power amplifier
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23 cm Antennas
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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 (?...)

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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
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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

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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 gt 500 Km
• European record 1400 km

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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

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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 -gt 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 components
24 GHz station components
Antenna relay
Toshiba 24 GHz amplifier
DB6NTX-tal Oscillator
Exciter 2m 24 GHz
25
Examples of 24 GHz stations
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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 144.175 MHz To F 144.390 MHz IARU EUR
  432.350 MHz
• DXCLUSTER CONVERS WWW.ON4KST.COM (also via
  GSM/GPRS)

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10 MHz frequency standard
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In the box
Display processor
10 MHZ PLL
GPS RX
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LO PLL
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LO driver for microwave frequencies
Locking the OCXOs to the 10 MHz frequency standard
G8ACE OCXO
LO PLL
124.500 MHz out
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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

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Contests the ON4SHF sites
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Contests the ON4SHF antennas
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Contests the ON4SHF operators
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Activity days - ON4SHF/P
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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!?)

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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

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2
70
6m
13
9
6-3cm
903
12-6mm
38
Thatss all

• JOIN THE CLUB

It is question time
on4cdu, on4iy
39
Back-up slides
40
Detailed Photos 10 GHz station
Transverter DB6NT 2m -gt 3 cm
10 GHz Pre-amplifier
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Attenuation at 24 GHz
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Beacon

• 10 GHz beacon ON0KUL/B