Over-the-air Testing of a 32 x 32 Daisy Chain MIMO Antenna

We are currently developing a new concept of large-scale MIMO systems, called “Daisy Chain MIMO Antenna,” that utilizes circular beam scanning array technology. Great emphasis is placed on a way of achieving a large-scale MIMO antenna at a mobile side that provides full-azimuth coverage. This paper presents the over-the-air (OTA) testing of a 32 × 32 daisy chain MIMO array antenna using a two-dimensional fading emulator. The MIMO antenna presented in this paper comprises 64 half-wavelength dipole antenna elements arranged in a daisy chain array structure, where 32 subarrays are formed by pairing dipole elements in each subarray; the antenna yields 32 independent subchannels for MIMO transmission, and covers all communication targets regardless of their position relative to the array. The measured results using a fading emulator show that the developed MIMO antenna can provide a channel capacity of more than 200 bits/s/Hz at a signal-to-noise power ratio (SNR) of 30 dB over 360 degrees in azimuth, which is equivalent to 20 Gbps for a bandwidth of 100 MHz.