  Magnetic field induced multiple non-Dirac nodal-lines are found to emerge in
the triplet dispersion bands of a frustrated spin-1/2 antiferromagnetic model
on the CaVO lattice. Plaquette and bond operator formalisms have been employed
to obtain the triplet plaquette and bond excitations for two different
parameter regimes in the presence of nearest and next-nearest-neighbor
Heisenberg interactions based on the plaquette-resonating-valence-bond and
dimerized ground states, respectively. In the absence of magnetic field a pair
of six-fold degenerate nodal-loops with distinct topological feature is noted
in the plaquette excitations. They are found to split into three pairs of
two-fold degenerate nodal-loops in the presence of magnetic field. In the other
parameter regime, system hosts two-fold degenerate multiple nodal-lines with a
variety of shapes in the triplon dispersion bands in the presence of magnetic
field. Ground state energy and spin gap have been determined additionally for
the two regimes. Those nodal-lines are expected to be detectable in neutron
scattering experiment on the frustrated antiferromagnet, CaV$_4$O$_9$.
