Additive manufacturing (AM) has become more important and common in recent years. Advantages of AM include the ability to rapidly design and fabricate samples much faster than traditional manufacturing processes and to create complex internal geometries. Materials are crucial components of microwave systems and proper and accurate measurement of their dielectric properties is important to aid a high level of accuracy in design. There are numerous measurement techniques and finding the most appropriate method is important and requires consideration of all different factors and limitations. One limitation of sample preparation is that the sample size needs to fit in the measurement method. By utilizing the advantage of additive manufacturing, the material can be characterized using different measurement methods. In this paper, the additive manufacturing process and dielectric measurement methods have been critically reviewed. The test specimens for measuring dielectric properties were fabricated using fused filament fabrication (FFF)-based additive manufacturing and were measured using four different commercial dielectric properties measurement instruments including split post dielectric resonator (SPDR), rectangular waveguide, TE_01δ cavity resonator, and open resonator. The measured results from the four techniques have been compared and have shown reasonable agreement with measurements within a 10 percent range.

This paper describes a novel method of characterizing complex permittivity using a complementary frequency selective surface (CFSS). The CFSS provides a passband behavior and the change in the passband when a material under test (MUT) is placed adjacent to the CFSS has been used for retrieving of the complex permittivity of the MUT. The complex permittivity of the MUT are determined based on the measured bandpass resonant frequency and insertion loss of the CFSS with the MUT. This is an amplitude-only method where phase measurements are not required. This technique offers a convenient, fast, low-cost and nondestructive measurement that is not restricted by the sample size or shape.