Enhancing Vector Network Analysis With a Photonic Frequency Extender Setup

We present a photonic ultrawideband frequency extension for a commercial vector network analyzer (VNA) to perform free-space measurements in a frequency range from 70 to 520 GHz with a hertz level resolution. The concept is based on the synchronization of continuous-wave (CW) lasers with highly frequency-stable electronic emitter sources as a reference. The use of CW photomixers with bandwidths up to several terahertz (THz) allows for the straightforward expansion of the covered frequency range to 1 THz or even beyond. This can be achieved, for instance, by cascading additional lasers within the synchronization scheme. Consequently, the necessity for additional frequency extender modules, as seen in current state-of-the-art VNAs, is eliminated, thereby reducing the complexity and cost of the system significantly. To showcase the capabilities of the photonic vector network analyzer (PVNA) extender concept, we conducted S21 transmission measurements of various cross-shaped bandpass filters and waveguide-coupled high-frequency (HF) components. In addition, the analyzed magnitude and phase data were either compared to electromagnetic (EM) simulations or referenced against data obtained from commercial electronic frequency extender modules.