Waveguide joint design and validation for use in acoustic vector-corrected network analysers

Abstract

The Vector-corrected Network Analyser (VNA) has been an indispensable tool for many decades in the field of RF and microwave engineering where the availability of calibrated and traceable results is taken for granted. However, calibrated and traceable measurements are not so easily available in the acoustic domain. In an effort to allow such measurements, a dual-port acoustic vector network analyser (AVNA) has been designed and built. The calibration of this test and measurement system hinges on the repeatability of the uncalibrated system and its acoustic waveguide joints. The first generation of acoustic waveguide joints have been 3D printed with a high precision printer and designed to include alignment pins, O-rings, and a reinforcing ‘clip’ system to allow for a consistent bolt torque without damaging the plastic waveguide. We show that the resulting variation in measurements between cycles of disassembly and reassembly is acceptably small and will allow for calibration of the system. Three-dimensional printed titanium joints show increased rigidity and ease of use but similar repeatability.