This paper presents a multi-antenna external reader system that enables orientation insensitive communication with implantable medical devices (IMDs) for wireless biomedical applications. The proposed system consists of a circular array with six loop antennas. The antenna placement and orientations are determined by analyzing the near-field magnetic field variations of the loop antenna. The electromagnetic simulations show that the received power at the proposed external reader with six antennas only varies about 5 dB for any given orientation of the implanted antenna, which is highly significant compared to the 20-35 dB variation with a single external antenna. A prototype of the proposed multi-antenna external reader is then implemented using custom-designed PCBs that interconnect loop antennas, transceiver ICs, and commercially-available circuit components. Based on measurement results, the received power in the external reader only varies about 3 dB when the miniaturized antenna rotates with respect to the x-axis. These measurements show good agreement with the simulated reader.