Electronic device structures such as structures containing antennas, connectors, welds, electronic device components, conductive housing structures, and other structures can be tested for faults using a non-contact test system. The test system may include a vector network analyzer or other test unit that generates radio-frequency tests signals in a range of frequencies. The radio-frequency test signals may be transmitted to electronic device structures under test using an antenna probe that has one or more test antennas. The antenna probe may receive corresponding radio-frequency signals. The transmitted and received radio-frequency test signals may be analyzed to determine whether the electronic device structures under test contain a fault.