Thomas Berenz, MPIfR Bonn1 RF fiber optics 4 th SKADS Workshop, Lisbon, 2-3 October 2008 RF fiber optics Analog RF transmission with mechanically stressed fibers

Thomas Berenz, MPIfR Bonn2 RF fiber optics 4 th SKADS Workshop, Lisbon, 2-3 October 2008 Introduction Advantages of fiber links: –Bandwidth depends mainly on the electrical components –Very long distances can be achieved Current installation in the Effelsberg telescope: –400m from primary focus cabin to faraday room –Transmission of RF signals through coaxial cables (25 1GHz) –Max. useable bandwidth < 1 GHz Analog transmission is able to avoid the bandwidth bottleneck

Thomas Berenz, MPIfR Bonn3 RF fiber optics 4 th SKADS Workshop, Lisbon, 2-3 October 2008 Analog fiber links Miteq SCM Series 0.1 – 18 GHz Miteq MDD Series 0.1 – 11 GHz 9/125 single mode fiber with FC/APC connectors Laser is modulated directly

Thomas Berenz, MPIfR Bonn4 RF fiber optics 4 th SKADS Workshop, Lisbon, 2-3 October 2008 Broadband measurement

Thomas Berenz, MPIfR Bonn5 RF fiber optics 4 th SKADS Workshop, Lisbon, 2-3 October 2008 Results of broadband meas TP_in: nearly constant TP_out: -0,47 – 0,25 dB

Thomas Berenz, MPIfR Bonn6 RF fiber optics 4 th SKADS Workshop, Lisbon, 2-3 October 2008 VNA Measurements Build up at the lab bench No loop Miteq SCM Transmitter (18 GHz BW) Miteq SCM Receiver (18 GHz BW) Miteq MDD Transmitter (11 GHz BW) Miteq MDD Receiver (11 GHz BW) 100m 9/125 SM fiber 2m 9/125 SM fiber

Thomas Berenz, MPIfR Bonn7 RF fiber optics 4 th SKADS Workshop, Lisbon, 2-3 October 2008 Measurement setup

Thomas Berenz, MPIfR Bonn8 RF fiber optics 4 th SKADS Workshop, Lisbon, 2-3 October GHz Tx + 18 GHz Rx

Thomas Berenz, MPIfR Bonn9 RF fiber optics 4 th SKADS Workshop, Lisbon, 2-3 October GHz Tx + 11 GHz Rx

Thomas Berenz, MPIfR Bonn10 RF fiber optics 4 th SKADS Workshop, Lisbon, 2-3 October GHz Tx + 18 GHz Rx

Thomas Berenz, MPIfR Bonn11 RF fiber optics 4 th SKADS Workshop, Lisbon, 2-3 October GHz Tx + 11 GHz Rx

Thomas Berenz, MPIfR Bonn12 RF fiber optics 4 th SKADS Workshop, Lisbon, 2-3 October 2008 Summary MDD (11 GHz) Receiver: ∆A = 0.22 dB SCC (18 GHz) Receiver: ∆A = 0.78 dB Transmitter has no influence Same measurements with 2m fiber instead of 100m: no change  Fiber length has no influence Measurments with the fiber installed in the telescope are compareable with those in the lab although the fiber is different  Fiber type has no influence

Thomas Berenz, MPIfR Bonn13 RF fiber optics 4 th SKADS Workshop, Lisbon, 2-3 October 2008 Conclusion Changes in insertion loss: Effect seems to depend on birefrigence caused by mechanical force applied to the fiber. Together with a polarization sensitivity of the photodiode this can cause the difference in insertion loss. Changes in frequency response: Still an open question; Has to be investigated further

Thomas Berenz, MPIfR Bonn14 RF fiber optics 4 th SKADS Workshop, Lisbon, 2-3 October 2008 Questions