300-GHz band millimeter-wave spectrum measurement system with pre-selector

Recent research is progressing into development of systems using frequency bands above 100 GHz, which is effective for short-range and broadband communications. At spectrum analysis in these frequency bands, generally either a down converter or a harmonic mixer is used to convert the frequencies to a band that can be observed by a conventional spectrum analyzer. In this case, unwanted signal components (Spurious responses) are often seen during measurement. Non-linearity in the measurement system generates harmonic components due to the input signals. Therefore, these harmonic components are mixed at spectrum observation and it becomes difficult to distinguish one from the other. To overcome this problem, we have constructed a 300-GHz band spectrum measurement system using a novel pre-selector design and describe the results of evaluation using this system.