134GHz – The new frontier134GHz – The new frontier

Sam Jewell, G4DDKSam Jewell, G4DDK

RAL 2007RAL 2007

The UK amateur MMW bands The UK amateur MMW bands above 100GHzabove 100GHz

122,250-123,000 MHz   Secondary user 134,000-136,000 MHz   Primary user   136,000-141,000MHz    Secondary user

241,000-248,000 MHz   Secondary user248,000-250,000 MHz   Primary user  

What is the attraction of these What is the attraction of these bands?bands?

Like climbing a mountain. Because it’s there!

Why 134GHz?Why 134GHz?

• Lots already happening on 122GHzLots already happening on 122GHz

• Less path loss than 122GHzLess path loss than 122GHz

• It’s an amateur radio primary band – It’s an amateur radio primary band – greater security of tenuregreater security of tenure

• Only one recorded UK QSO on the Only one recorded UK QSO on the band. And that by an ex-pat!band. And that by an ex-pat!

The problemsThe problems

• PropagationPropagation– Atmospheric gases absorptionAtmospheric gases absorption– Sky brightness Sky brightness – Rain lossRain loss– Foliage lossFoliage loss– Scatter lossScatter loss

• EquipmentEquipment– No commercial designsNo commercial designs

• DB6NT boards for 122 and 145GHzDB6NT boards for 122 and 145GHz

Atmospheric lossesAtmospheric lossesAttenuation caused by Oxygen and water vapour at

10grm/m3

0.01

0.1

1

10

100

1 10 100 1000

Frequency (GHz)

Att

en

ua

tio

n (

dB

/km

)

4724 76

122122

134

40% RH at 25C

Water vapour

Oxygen

Path lossPath loss

Free space + atmospheric gases absorption

@ 134GHz and 40% RH at 25CThen additional losses are approximately1.2dB/km

Over 25km the total loss would be: 162 + 30 = 192dB

Horizon brightness at Horizon brightness at microwavemicrowave

What the antenna seesBetween 432MHz and 10GHz~170k average

What the antenna sees at 134GHz~290kRef. FCC Bulletin 70. 1997

Sky brightness at zenithSky brightness at zenith

Sky temperature~80 - 100k

This has implicationsFor satellite and EMEOn the MMW bands

134GHz equipment134GHz equipment

Wideband or narrowband?Wideband or narrowband?

For weak signal operation - For weak signal operation - narrowband!narrowband!

134GHz Equipment134GHz Equipment

The band is 7GHz wide. Where do we The band is 7GHz wide. Where do we operate?operate?– G4FRE and G7FRE chose an ‘odd’ G4FRE and G7FRE chose an ‘odd’

frequency to suit their equipment. Good frequency to suit their equipment. Good but not ideal.but not ideal.

– Frequency stability and accuracy Frequency stability and accuracy paramountparamount

– LO phase noise equally important.LO phase noise equally important.

134GHz equipment134GHz equipment

Traditionally band edges have been a Traditionally band edges have been a multiple of 1152MHzmultiple of 1152MHz– Multiplier systems Multiplier systems

134GHz134GHz

• CandidatesCandidates– 1152MHz x 117 = 134.784GHz 1152MHz x 117 = 134.784GHz – 1152MHz x 118 = 135.936GHz1152MHz x 118 = 135.936GHz

• HoweverHowever– 1152 is also a very convenient multiplier 1152 is also a very convenient multiplier

number. It has lots of integer sub number. It has lots of integer sub multiples to choose from.multiples to choose from.

The 134GHz multiplier The 134GHz multiplier systemsystem

Multiplying direct to the transmit Multiplying direct to the transmit frequency_frequency_Whilst admirable it ignores a very Whilst admirable it ignores a very important point. You still need a important point. You still need a receiver local oscillator. receiver local oscillator.

With mixer systems you get both With mixer systems you get both transmit and receive in one go. transmit and receive in one go. However, transmit power will be However, transmit power will be lower than direct multiplier transmit lower than direct multiplier transmit systems can provide.systems can provide.

134GHz 134GHz

• 117MHz (134.784GHz) + 144MHz117MHz (134.784GHz) + 144MHz

= 134.928GHz= 134.928GHzLO and image both in bandLO and image both in band

• 118MHz (135.936GHz) + 144MHz118MHz (135.936GHz) + 144MHz

= 136.080GHz= 136.080GHzLO and image both in band, however signalLO and image both in band, however signal

out of the primary allocationout of the primary allocation

The 134GHz multiplier The 134GHz multiplier scheme 1scheme 1

117MHz11232MHz 33696MHz

Commercialmultiplier

144MHz IF 134.784GHzGHzDB6NTDB6NT145GHz PCB145GHz PCB

DB6NT multiplier

134.928GHz

The 134GHz multiplier The 134GHz multiplier scheme 2scheme 2

116MHz11136MHz 33408MHz

Commercialmultiplier

1296MHz IF 133.632GHz133.632GHzDB6NTDB6NT145GHz PCB145GHz PCB

DB6NT multiplier

134.928GHz

* Note, both LO and image out of band

The 134GHz multiplier The 134GHz multiplier scheme 3scheme 3

116MHz DFS

11136MHz

66.816GHzDB6NTTripler

133.632GHz133.632GHzDB6NTDB6NT145GHz PCB145GHz PCB

1296MHz IF

DB6NT multiplier

134.928GHz

22272MHzDB6NTDoubler +amplifier

Based on the DC0DA articleIn DUBUS 1/2007

DB6NT 145GHz mixerDB6NT 145GHz mixer

144MHz

33GHz

134GHz

The 117MHz The 117MHz Direct Frequency SynthesiserDirect Frequency Synthesiser

The 116MHz The 116MHz Direct Frequency SynthesiserDirect Frequency Synthesiser

Equipment capabilityEquipment capability

Noise figure 20dBNoise figure 20dBTransmit power -17dBmTransmit power -17dBmAntenna gain 50dBiAntenna gain 50dBiBandwidth 500Hz (+27dB/Hz)Bandwidth 500Hz (+27dB/Hz)

Path loss capabilityPath loss capability Receiver noise power (Pn) = 20+27-50-174 = -Receiver noise power (Pn) = 20+27-50-174 = -

177dBm177dBmTransmit power P (eirp) = -17+50 = +33dBmiTransmit power P (eirp) = -17+50 = +33dBmiTotal capability = 177 + 33 Total capability = 177 + 33

= 210dBm= 210dBm

Path lossPath loss

Free space + atmospheric gases absorption

Over 25km the total loss would be: 162 + 30 = 192dB

Therefore the path margin over 25km = 210 – 192 = 18dB!

With no atmospheric gases we could go 200kmBut 175km * 1.2 = 210dB…………

A 0dB SNR is achieved at 35km with this equipment.

134GHz narrowband 134GHz narrowband segmentsegment

134.928 – 134.930GHz