1. WP06_AntennaIF

2. WP06_AntennaIF 3 principal modules switch amplifier (= ATA ‘PAM’) –includes attenuators (0-60 dB), power detector, and bias tee for the laser transmitter –integrate with CANbus controller? –aluminum box; mount flange to temperature regulated plate, or if necessary to separate thermoelectric cooler laser transmitter (= ATA ‘OTX’)

3. WP06_AntennaIF: amplifier module = ATA post-amp module frequency range 500 MHz – 10 GHz gain flat within ±3 dB across band input noise temp < 1200 K input pwr level –50 dBm to +10 dBm (!) linearity better than 1% gain stable to 1 part in 10 3, if temperature regulated to 0.1 C

4. WP06_AntennaIF: prototype ATA PAM

5. WP06_AntennaIF prototype PAM; gain ~ 50 dB

6. amplifier module: gain compression ~ 1% at 1.5 dBm output power output pwr gain,.02 dB/div input pwr swept from –60 dBm to –45 dBm

7. WP06_AntennaIF temperature dependence of gain 0.3 dB / 20 C  0.4% / C gain stability of 10 -3 requires ±0.1 C temp regulation high freq ripples due to poor output match

8. WP06_AntennaIF: optical transmitter NEC NX8560LJ 1550 nm DFB laser + electroabsorption modulator + TEC

9. WP06_AntennaIF: laser transmitter = ATA OTX module includes: –NEC NX8560LJ laser EA modulator thermoelectric cooler photodiode power monitor thermistor –TEC controller (5 V, ~ 1 amp) –laser current supply –modulator DC bias (bias tee located in amplifier module) Photonics Inc will build 700 modules for ATA; cost approx $2.5 K each

10. WP06_AntennaIF open questions will detector on amplifier module be used for beamswitched continuum measurements? if so, will switched-power demodulation be done at the IF CANbus node? how will mirror position be transmitted? power supply: requires ~ 1 amp at 5 V; is it necessary to get this from 24 V dc-dc converter can RF power damage the electroabsorption modulator; how to protect without compromising linearity?

11. WP02_LOreference key features distributes two reference frequencies (1100-1260 MHz tunable, 10 MHz fixed) from control building to antennas via singlemode optical fiber linelength system continuously monitors electrical delay through each fiber to an accuracy of ~0.1 picosec, approx 8° phase at 230 GHz 1 pps tick distributed to antennas, as a missing pulse on the 10 MHz reference allow for 3 subarrays operating with different reference frequencies

12. WP02_LOreference: current BIMA system

13. WP02_LOreference phase noise vs optical pwr optical pwr  rms coax6.3° -2 dBm6.65° -6 dBm7.05° -9 dBm8.31°

14. WP02_LOreference current BIMA fiber distribution approx 135 feet (200 nsec) of fiber exposed to outdoor air temp

15. linelength monitor via roundtrip phase 135’ of fiber at outdoor air temp (  = 200 nsec)  ~ 2 psec/C  ~ 180°/C at 230 GHz

16. WP02_LOreference linelength options TRX RX CPLTRX RX CPL 1.echo on 2 nd fiber do fiber lengths track each other? 2.echo on same fiber temperature coefficients of circulators? reflections from bad connectors? optical circulators

17. WP02_LOreference: 3-fiber test echo from 1 antenna coupled back on 3 separate fibers: 3 independent measurements

18. WP02_LOreference: 3-fiber test 0.2 psec glitches during slew 1 psec long term drifts due to cabin temp change

19. example of linelength correction raw data linelength-corrected 3c454.3, 86 GHz, baseline 2-8, through sunrise

20. thermal tests of 10 MHz fiber link from ‘good’ antenna

21. thermal tests of 10 MHz fiber link from ‘bad’ antenna

22. slow/fast thermal ramp – phase structure remains the same

23. probable explanat ion fiberphotodiode 1.gap acts like Fabry-Perot cavity; increasing temp expands gap, causes periodic variation in laser power at photodiode 2.laser power affects diode capacitance or resistance, hence changes phase of RF signal substituting APC connector seems to cure the problem

24. WP02_LOreference short term: with 10 MHz thermal problem fixed, reinstall on BIMA in November longer term: –test optical circulators? –one laser/antenna to make subarrays easier? –convert to 1550 nm NEC lasers?