I think that the simplest explanation for the BIPM's recommendation that the antenna cables be matched to the antenna output impedance and the GPS receivers input impedance is as follows:
If one has gone to the trouble and expense of installing an antenna that is relatively insensitive to multipath effects, then using an unmatched cable to connect the antenna to the receiver in effect reintroduces multipath signals into the receiver input, reflections on the cable due to antenna and receiver mismatch are no different in character to multipath signals. The magnitude of the effects of cable mismatch will depend on the degree of mismatch at the antenna and at the receiver as well as the cable attenuation, and the cable length For the less accurate timing receivers such as the Trimble Thunderbolt such effects may be insignificant as other the effect of other timing error sources are much larger. Bruce _______________________________________________ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
