This paper deals with low cost and non-invasive wideband holographic microwave imaging system that operates in 5.05GHz-8.23GHz band. Emphasis is given here to detect tumor in 2D breast phantom using 18 bowtie antennas with 4 antennas serving as transmitters (Tx) and 14 antennas as receivers (Rx). Holographic microwave simulations have been done using MATLAB to detect the existence of tumor and its size. Results are shown for 2D reconstructed sliced images of the breast taken for four different transmitters. Holographic simulations demonstrate that array proposed in this paper has the ability to detect tumor of a size as small as 1.5 mm located at (x, y, z) = (0, 40, 30) within the breast tissues.