In order to accurately test directional or multiplexed systems in a lab environment, a testbed should simulate both directional wireless channels and propagation delay. Using one or more RF lenses, one can test a radio system that uses switched or adaptively steerable antennas: one side is switched by an ldquoenvironmentrdquo controller, the other by the the discovery and tracking loop of the radio system. True path delay testing can be done by using analog RF-to-optical converters and miles of low-cost, low-loss fiber optics. Apart from verifying latency, this test can also determine if there are issues with ACK or other timeouts: information unavailable by simply attenuating a link to simulate distance.