A test system for testing multiple-input and multiple-output (MIMO) systems is provided. The test system may convey radio-frequency (RF) signals bidirectionally between a device under test (DUT) and at least one base station. The DUT may be placed within a test chamber during testing. An antenna mounting structure may surround the DUT. Multiple antennas may be mounted on the antenna mounting structure to transmit and receive RF signals to and from the DUT. A first group of dual-polarized antennas may be coupled to the base station through downlink circuitry. A second group of dual-polarized antennas may be coupled to the base station through uplink circuitry. The uplink and downlink circuitry may each include a splitter/combiner, channel emulators, amplifier circuits, and switch circuitry. The channel emulators and amplifier circuits may be configured to provide desired path loss, spatial interference, and channel characteristics to model real-world wireless network transmission.