Over-the-Air Characterization Techniques for Antenna-Coupled Direct-Detectors at Terahertz Frequencies
The performance of terahertz direct-detectors is continuously increasing in terms of coverage and sensitivity, placing higher constraints on the test benches used for characterization. Additionally, the relative differences between the hardware and simulations are often on the order of a few decibel. In this contribution, we present a detailed measurement procedure for over-the-air broadband characterization of direct detection terahertz imagers. In our setup the modulation frequency can be customized in order to maximize the measurement dynamic range up to 30 dB and to minimize the impact of the setup on the accuracy of the results. As a demonstrator, we have characterized a dual-polarized array with a high element density over the 325 – 500 GHz frequency band and achieved a hardware-to-model agreement below 1 dB for the four measured elements within this array over almost the entire frequency band of interest.