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Detecting a signal from the Epoch of Reionisation (EoR) requires an exquisiteunderstanding of galactic and extra-galactic foregrounds, low frequency radioinstruments, instrumental calibration, and data analysis pipelines. In thiswork we build upon existing work that aims to understand the impact ofcalibration errors on 21-cm power spectrum (PS) measurements. It is wellestablished that calibration errors have the potential to inhibit EoRdetections by introducing additional spectral features that mimic the structureof EoR signals. We present a straightforward way to estimate the impact of awide variety of modelling residuals in EoR PS estimation. We apply thisframework to the specific case of broken dipoles in Murchison Widefield Array(MWA) to understand its effect and estimate its impact on PS estimation.Combining an estimate of the percentage of MWA tiles that have at least onebroken dipole (15%-40%) with an analytic description of beam errors induced bysuch dipoles, we compute the residuals of the foregrounds after calibration andsource subtraction. We find that that incorrect beam modelling introduces biasin the 2D-PS on the order of $\sim 10^3\, \mathrm{mK}^2 \,h^{-3}\,\mathrm{Mpc}^{3}$. Although this is three orders of magnitude lower thancurrent lowest limits, it is two orders of magnitude higher than the expectedsignal. Determining the accuracy of both current beam models and directiondependent calibration pipelines is therefore crucial in our search for an EoRsignal.

Calibration and 21-cm Power Spectrum Estimation in the Presence of Antenna Beam Variations