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134GHz – The new frontier

134GHz – The new frontier. Sam Jewell, G4DDK RAL 2007. The UK amateur MMW bands above 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 user 248,000-250,000 MHz   Primary user.

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134GHz – The new frontier

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  1. 134GHz – The new frontier Sam Jewell, G4DDK RAL 2007

  2. The UK amateur MMW bands above 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 user 248,000-250,000 MHz   Primary user

  3. What is the attraction of these bands? Like climbing a mountain. Because it’s there!

  4. Why 134GHz? • Lots already happening on 122GHz • Less path loss than 122GHz • It’s an amateur radio primary band – greater security of tenure • Only one recorded UK QSO on the band. And that by an ex-pat!

  5. The problems • Propagation • Atmospheric gases absorption • Sky brightness • Rain loss • Foliage loss • Scatter loss • Equipment • No commercial designs • DB6NT boards for 122 and 145GHz

  6. Atmospheric losses 122 122 Water vapour Oxygen 134 40% RH at 25C

  7. Path loss Free space + atmospheric gases absorption @ 134GHz and 40% RH at 25C Then additional losses are approximately 1.2dB/km Over 25km the total loss would be: 162 + 30 = 192dB

  8. Horizon brightness at microwave What the antenna sees Between 432MHz and 10GHz ~170k average What the antenna sees at 134GHz ~290k Ref. FCC Bulletin 70. 1997

  9. Sky brightness at zenith Sky temperature ~80 - 100k This has implications For satellite and EME On the MMW bands

  10. 134GHz equipment Wideband or narrowband? For weak signal operation - narrowband!

  11. 134GHz Equipment The band is 7GHz wide. Where do we operate? • G4FRE and G7FRE chose an ‘odd’ frequency to suit their equipment. Good but not ideal. • Frequency stability and accuracy paramount • LO phase noise equally important.

  12. 134GHz equipment Traditionally band edges have been a multiple of 1152MHz • Multiplier systems

  13. 134GHz • Candidates • 1152MHz x 117 = 134.784GHz • 1152MHz x 118 = 135.936GHz • However • 1152 is also a very convenient multiplier number. It has lots of integer sub multiples to choose from.

  14. The 134GHz multiplier system Multiplying direct to the transmit frequency_ Whilst admirable it ignores a very important point. You still need a receiver local oscillator. With mixer systems you get both transmit and receive in one go. However, transmit power will be lower than direct multiplier transmit systems can provide.

  15. 134GHz • 117MHz (134.784GHz) + 144MHz = 134.928GHz LO and image both in band • 118MHz (135.936GHz) + 144MHz = 136.080GHz LO and image both in band, however signal out of the primary allocation

  16. The 134GHz multiplier scheme 1 11232MHz 33696MHz Commercial multiplier 117MHz DB6NT multiplier 134.928 GHz 144MHz IF 134.784GHz DB6NT 145GHz PCB

  17. The 134GHz multiplier scheme 2 11136MHz 33408MHz Commercial multiplier 116MHz DB6NT multiplier 134.928 GHz 1296MHz IF 133.632GHz DB6NT 145GHz PCB * Note, both LO and image out of band

  18. 1296MHz IF The 134GHz multiplier scheme 3 22272MHz DB6NT Doubler + amplifier 11136MHz 116MHz DFS DB6NT multiplier 66.816GHz DB6NT Tripler 134.928 GHz 133.632GHz DB6NT 145GHz PCB Based on the DC0DA article In DUBUS 1/2007

  19. DB6NT 145GHz mixer 134GHz 144MHz 33GHz

  20. The 117MHz Direct Frequency Synthesiser

  21. The 116MHz Direct Frequency Synthesiser

  22. Equipment capability Noise figure 20dB Transmit power -17dBm Antenna gain 50dBi Bandwidth 500Hz (+27dB/Hz) Path loss capability Receiver noise power (Pn) = 20+27-50-174 = -177dBm Transmit power P (eirp) = -17+50 = +33dBmi Total capability = 177 + 33 = 210dBm

  23. Path 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 200km But 175km * 1.2 = 210dB………… A 0dB SNR is achieved at 35km with this equipment.

  24. 134GHz narrowband segment 134.928 – 134.930GHz

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