  The present talk consists of two parts. The first one is allocated for
consideration of the dimension of bilocal meson fields for quark-antiquark
meson systems, which have been so far treated as the bosonic fields independent
of constituent quark flavors, in the covariant oscillator quark model.
Revisiting the electromagnetic currents of quark-antiquark meson systems, we
show that the bilocal meson fields should be bosonic for light-quark meson
systems, while fermionic for heavy-light and heavy-heavy meson systems. In the
second part we apply the effective electromagnetic interactions of meson
systems derived in the first part to radiative decay processes for the excited
states of light-quark mesons. The calculated results for the $\pi \gamma$ decay
widths of the $a_1(1260)$, $a_2(1320)$, $b_1(1235)$ and $\pi_2(1670)$ mesons
are in fair agreement with experiment, except for the $b_1(1235)$ meson. As for
the $\rho(770)^0 \gamma$ decay width of the $f_1(1285)$ the present model
strongly supports the experimental results in 1995 and 2016, respectively, of
VES and CLAS Collaborations, not the average value by the Particle Data Group.
