  Next generation radio telescope arrays are being designed and commissioned to
accurately measure polarized intensity and rotation measures across the entire
sky through deep, wide-field radio interferometric surveys. Radio
interferometer dish antenna arrays are affected by direction-dependent (DD)
gains due to both instrumental and atmospheric effects. In this paper we
demonstrate the effect of DD errors for parabolic dish antenna array on the
measured polarized intensities of radio sources in interferometric images. We
characterize the extent of polarimetric image degradation due to the DD gains
through wide-band VLA simulations of representative point source simulations of
the radio sky at L-Band(1-2GHz). We show that at the 0.5 gain level of the
primary beam (PB) there is significant flux leakage from Stokes $I$ to $Q$, $U$
amounting to 10\% of the total intensity. We further demonstrate that while the
instrumental response averages down for observations over large parallactic
angle intervals, full-polarization DD correction is required to remove the
effects of DD leakage. We also explore the effect of the DD beam on the
Rotation Measure(RM) signals and show that while the instrumental effect is
primarily centered around 0 rad-m$^{-2}$, the effect is significant over a
broad range of RM requiring full polarization DD correction to accurately
reconstruct RM synthesis signal.
