Uncertainty Assessment of a Small Rectangular Anechoic Chamber: From Design to Operation

Abstract

Anechoic chambers are widely used to measure antenna parameters because of the free reflection conditions inside them. Recently, there has been increasing research into antennas working at frequencies from 20 to 70 GHz. General-purpose anechoic chambers are usually between 5 and 10 m in size, which leads to free-space distances longer than required at millimeter-wave frequencies and corresponding larger cables losses. Designing anechoic chambers tailored to such a frequency range would lead to minimum losses and improve measurement performance. If uncertainty is considered all the way from the design stage to operation, it will be easier to obtain highly accurate measurement outcomes. This article focuses on the issues related to uncertainty in a tailor-made millimeter-wave anechoic chamber at every step before achieving a fully functional measurement system. This includes setting the requirements for the chamber, calculating its dimensions, designing the structure, and selecting the building materials, in order finally to characterize its performance by measuring the insulation from external signals and the ripple in the quiet zone. This process has resulted in a full description of design, construction, and operation stages of an anechoic chamber from the point of view of the control on the measurement uncertainty.