  High-resolution imaging is crucial for exploring the origin and mechanism of
radio emission in quasars, especially at high redshifts. We present 1.5 GHz
Very Long Baseline Array (VLBA) images of the radio continuum emission from the
radio-intermediate quasar (RIQ) J2242+0334 at $z = 5.9$. This object was
previously detected at both 1.5 GHz and 3 GHz with the Karl G. Jansky Very
Large Array (VLA) as a point source. However, there is no clear detection in
the VLBA images at both the full resolution of 10.7 milliarcsecond (mas)
$\times$ 4.5 mas (61.7 pc $\times$ 26.0 pc) and a tapered resolution of 26 mas
$\times$ 21 mas (150 pc $\times$ 121 pc). This suggests that the radio emission
from the quasar is diffuse on mas scales with surface brightness fainter than
the $3\sigma$ detection limit of 40.5 $\mu \rm Jy \ beam^{-1}$ in the full
resolution image. The radio emission in the RIQ J2242+0334 is likely to be
wind-like (i.e., diffuse) rather than in the form of collimated jets. This is
different from the previous radio detections of the most luminous quasars at $z
\sim$6 which are usually dominated by compact, high brightness temperature
radio sources. Meanwhile, compared with RIQs at low redshifts, the case of
J2242+0334 suggests that not all RIQs are beamed radio-quiet quasars. This
optically faint RIQ provides an important and unique example to investigate the
radio activity in the less powerful active galactic nuclei at the earliest
cosmic epoch.
