According to some embodiments, a tester tests one or more DUTs by utilizing one or more respective reference devices. The tester comprises one or more test sites and one or more test circuits operatively coupled to each of the test sites. Each test site is configured to: hold a reference device and a DUT, transmit a transmitted electromagnetic RF signal including a test data pattern to the DUT, and receive a received electromagnetic RF signal emitted from the DUT. The test circuits are configured to: receive a first electrical signal converted from the received electromagnetic RF signal, extract first data from the first electrical signal, determine a first error rate between the test data pattern and the first data, and generate a test result on the basis of the first error rate.