In this paper, a novel assembly of the conformal antenna array for microwave breast imaging (MWI) is proposed. A pair of 6-element hemispherical antenna arrays is proposed using an optimised author-designed thin-film UWB antenna integrated into the dielectric spacer. A single 6-element array allows detection of the tumour using a rough version of the monostatic radar-based method. Also, a larger element array such as a 12-element array can be assembled with the 8-element array as the block unit to improve the accuracy of imaging results. The performance of the proposed configuration of the conformal array is validated in the CST Microwave Studio (MWS) and Design Studio (DS) software. In the simulation work, a realistic voxel-based phantom is introduced and exported from an MRI-scanned human breast. During the imaging stage, an effective estimation algorithm such as Delay-and-Sum (DAS) is implemented to create an energy distribution map by processing the scattered microwave signal received at different receiving antenna located around the breast area. Results show that a small tumour of 5 mm in diameter can be successfully detected in a 2-D image and localised using the proposed antenna array.