Over 100 GHz millimeter-wave spectrum measurement system with pre-selector

The recent start of R&D into Wireless Personal Networks (WPAN) and millimeter-wave wireless systems is creating an urgent need for development of a spectrum analyzer supporting accurate measurements in the frequency band above 100 GHz. However, there is no spectrum analyzer with a built-in pre-selector supporting spectrum analysis of wireless signals above 67 GHz. Such measurement is made generally by connecting a harmonic mixer or Block Down converter externally to a spectrum analyzer. In this case, generated unwanted signal components (spurious responses) are often seen during measurement, making it difficult to monitor the original signal components. This paper proposes development of a millimeter-wave spectrum measurement system incorporating a pre-selector function for wide dynamic range measurements with minimum unwanted signal components. We present the results of investigation into a prototype of the proposed system. We also measured a 120 GHz QPSK modulation wave to demonstrate the effectiveness of this system with pre-selector.