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

The UK amateur MMW bands above 100GHz 122, ,000 MHz Secondary user 134, ,000 MHz Primary user 136, ,000MHz Secondary user 241, ,000 MHz Secondary user 248, ,000 MHz Primary user

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

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

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

Atmospheric losses % RH at 25C Water vapour Oxygen

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

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

Sky brightness at zenith Sky temperature ~ k This has implications For satellite and EME On the MMW bands

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

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.

134GHz equipment Traditionally band edges have been a multiple of 1152MHz Traditionally band edges have been a multiple of 1152MHz –Multiplier systems

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

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.

134GHz 117MHz ( GHz) + 144MHz 117MHz ( GHz) + 144MHz = GHz = GHz LO and image both in band 118MHz ( GHz) + 144MHz 118MHz ( GHz) + 144MHz = GHz = GHz LO and image both in band, however signal out of the primary allocation

The 134GHz multiplier scheme 1 117MHz 11232MHz33696MHz Commercial multiplier 144MHz IF GHz GHzDB6NT 145GHz PCB DB6NT multiplier GHz

The 134GHz multiplier scheme 2 116MHz 11136MHz33408MHz Commercial multiplier 1296MHz IF GHzDB6NT 145GHz PCB DB6NT multiplier GHz * Note, both LO and image out of band

The 134GHz multiplier scheme 3 116MHz DFS 11136MHz GHz DB6NT Tripler GHzDB6NT 145GHz PCB 1296MHz IF DB6NT multiplier GHz 22272MHz DB6NT Doubler + amplifier Based on the DC0DA article In DUBUS 1/2007

DB6NT 145GHz mixer 144MHz 33GHz 134GHz

The 117MHz Direct Frequency Synthesiser

The 116MHz Direct Frequency Synthesiser

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

Path loss Free space + atmospheric gases absorption Over 25km the total loss would be: = 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.

134GHz narrowband segment – GHz