  This study presents an orbital phase-dependent analysis of three black widow
spider millisecond pulsars (BW MSPs), aiming to investigate the magnetic field
within the eclipse environment. The ultra-wide-bandwidth low-frequency receiver
(UWL) of the Parkes 'Murriyang' radio telescope is utilised for full
polarisation observations covering frequencies from 704-4032 MHz.
Depolarisation of pulsed emission is observed during the eclipse phase of three
BW MSPs namely, J0024-7204J, J1431-4715 and PSR J1959+2048, consistent with
previous studies of other BW MSPs. We estimated orbital phase dependent RM
values for these MSPs. The wide bandwidth observations also provided the
constraints on eclipse cutoff frequency for these BW MSPs. For PSR J0024-7204J,
we report temporal variation of the eclipse cutoff frequency coupled with
changes in the electron column density within the eclipse medium across six
observed eclipses. Moreover, the eclipse cutoff frequency for PSR J1431-4715 is
determined to be 1251 $\pm$ 80 MHz, leading to the conclusion that synchrotron
absorption is the primary mechanism responsible for the eclipsing.
Additionally, for PSR J1959+2048, the estimated cutoff frequency exceeded 1400
MHz, consistent with previous studies. With this investigation, we have doubled
the sample size of BW MSPs with orbital phase-resolved studies allowing a
better probe to the eclipse environment.
