The definition of the frequency response operator via the steady-state analysis in finite-dimensional linear continuous-time periodic (FDLCP) systems is revisited. It is shown that the frequency response operator is guaranteed to be well defined only densely on the linear space l(2), which is different from the usual understanding. Fortunately, however, it turns out that this frequency response operator can have an extension onto l(2) so that the equivalence between the time-domain H-2 norm ( respectively, the L-2-induced norm) and the frequency-domain H-2 norm ( respectively, the H-infinity norm of the frequency response operator) is recovered. Under some stronger assumptions, it is also shown that the frequency response operator can be viewed as a bounded operator from l(1) to l(1), which can also be established via the steady-state analysis.