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We present UV/optical spectropolarimetric modelling of thephenomenologically-based structure for quasars proposed by Elvis (2000). Inthis first paper of a series, we explore the continuum polarisation emergingfrom radiatively accelerated and bent winds that were vertically launched fromthe accretion disc in an active galactic nucleus (AGN). We simulate theradiative transfer occurring in Thomson scattering and dust extinction mediaover a range of morphological parameters and optical depths of the wind. Wedemonstrate that the wind geometry proposed by Elvis with aphenomenologically-derived bending angle of theta = 60deg still underestimatesthe observed optical polarisation percentage of type-1 and type-2 AGN and doesnot yet reproduce the expected dichotomy of the polarisation position angle. Torecover the observed polarisation properties, a smaller bending angle and someamount of dust shielding in the equatorial region should be considered. Atwo-phase outflow is found to generate both the observed polarisation dichotomyand acceptable levels of polarisation degree if the wind has a bending angletheta = 45deg, and the conical shells have a half-openingangle of 3deg <delta_theta < 10deg. The absorbing dust column at the wind base should be inthe range of 1 < tau_dust < 4 (tau being integrated over 2000 - 8000 Angs).Straightforward observational tests from spectropolarimetry and fromdetermining the number density of different AGN types can be performed tofurther constrain the wind geometry.

A structure for quasars under the scope of polarisation I. The UV/optical polarisation dichotomy of type-1 and type-2 AGN