  We address the radio frequency (RF) cavity experiment for probing dark
photons which is a modification of the light-shining-through-thin-wall
(LSthinW) setup with a relatively thin conducting barrier between cylindrical
emitter and hollow receiver. The regarding experimental facility allows to
probe dark photons effectively even in the off-shell regime, i. e. when dark
photons mass exceeds the driven frequency of the emitter cavity, that is pumped
by electromagnetic mode. We compare the sensitivity of two concrete setup
configurations: two cylindrical cavities placed to each other by an end-caps,
and nested geometry of the cavities in which the cylindrical receiver is
encapsulated into the emitter. We show that for a certain range of dark photon
mass the nested configuration can provide an enhanced sensitivity if one
compares that with a separated emitter setup.
