We have built a 20-antenna MIMO testbed at Portland State University (PSU) that allows us to take channel measurements across a variety of channel environments (indoors, outdoors, and PSU anechoic chamber). The testbed uses Skylark Wireless Iris radios and operates across a wide set of frequencies below 6 GHz. The testbed also allows us to change the antenna type and/or configuration and test their impact on the system performance.