  We report the high resolution radio observations and their analysis of a
radio-loud compact steep spectrum (CSS) quasar FIRST J164311.3+315618, one of
the members of a binary system. The second component of the system is a
radio-quiet AGN. The projected separation of this pair is 2.3 arcsec (15 kpc)
and it is one of the known smallest separation binary quasars. The multi-band
images of this binary system made with the Hubble Space Telescope showed that
the host galaxy of the radio-loud quasar is highly disturbed. The radio
observations presented here were made with the multi-element radio linked
interferometer network (MERLIN) at 1.66 GHz and 5 GHz. We show that the radio
morphology of FIRST J164311.3+315618 is complex on both frequencies and
exhibits four components, which indicate on the intermittent activity with a
possible rapid change of the jet direction and/or restart of the jet due to the
interaction with the companion. The radio components that are no longer powered
by the jet can quickly fade away. We suggest that this makes the potential
distortions of the radio structure to be short-lived phenomena. On the other
hand, our numerical simulations show that the influence of the companion can
lead to the prolonged current and future activity. FIRST J164311.3+315618 is an
unusual and statistically very rare low redshift binary quasar in which
probably the first close encounter is just taking place.
