  Using the Australia Telescope Compact Array (ATCA) we have imaged the fields
around five promising pulsar candidates to search for radio pulsar wind nebulae
(PWNe). We have used the ATCA in its pulsar gating mode; this enables an image
to be formed containing only off-pulse visibilities, thereby dramatically
improving the sensitivity to any underlying PWN. Data from the Molonglo
Observatory Synthesis Telescope were also used to provide sensitivity on larger
spatial scales. This survey found a faint new PWN around PSR B0906-49; here we
report on non-detections of PWNe towards PSRs B1046-58, B1055-52, B1610-50 and
J1105-6107. Our radio observations of the field around PSR B1055-52 argue
against previous claims of an extended X-ray and radio PWNe associated with the
pulsar. If these pulsars power unseen, compact radio PWN, upper limits on the
radio flux indicate that less than 1e-6 of their spin-down energy is used to
power this emission. Alternatively PSR B1046-58 and PSR B1610-50 may have
relativistic winds similar to other young pulsars and the unseen PWN is
resolved and fainter than our surface brightness sensitivity threshold. We can
then determine upper limits on the local ISM density of 2.2e-3 cm^-3 and 1e-2
cm^-3, respectively. Furthermore we constrain the spatial velocities of these
pulsars to be less than ~450 km/s and thus rule out the association of PSR
B1610-50 with SNR G332.4+00.1 (Kes 32). Strong limits on the ratio of unpulsed
to pulsed emission are also determined for three pulsars.
