(57) The apparatus is aimed at radio receivers on board vehicles in movement along a highway
without changes in tuning, and comprises: a plurality of emitting antennae (12, 14)
arranged at intervals along said highway, and respective radio-frequency amplifiers
(36, 42) connected to feed said antennae; an optical fiber line (18) adjacent to said
highway, fed at one end by an optical transmitter (28) driven by a radio-frequency
signal to be broadcast; means (30, 38) for tapping the radio-frequency signal from
the optical fiber line at each radio-frequency amplifier; and delay means (34, 40)
for delaying the radio-frequency signal having their input connected to the output
of said tapping means and their output connected to said radio-frequency amplifiers;
the delay introduced by each of said delay means being such that in the equisignal
region between every two adjacent emitting antennae the broadcast signal is substantially
coherent.
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