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Low-loss antenna cables

At SAOB, MUSB, and DIAB, low-loss antenna (<1.5 db per 30 meters at 1.5 GHz) cable was used. Normally, the signal from the receiver antenna is amplified to a high level, and subsequently attenuated over the length of the cable connecting the antenna to the receiver. This attenuation limits the physical distance between the receiver and the antenna as the signal-to-noise degrades. Traditionally, line amplifiers have been added as a remedy. The amplifiers may drift or become electrically unstable as they age. This would result in an impedance mismatch and an unknown but apparent change in the phase center of the antenna over the life of the experiment. In addition to eliminating the loss of signal which necessitated the line amplifier in the first place, the low loss cable is passive, and will not change in impedance with time.

In addition to the three new installations, the CMBB and HOPB stations were upgraded from high-loss antenna cable and line amplifiers to low-loss antenna cables.

Mark Murray
Tue Dec 1 19:23:10 PST 1998