Free Space Dielectric Techniques for Diamond Composite Characterization

• Published in: IEEE journal of microwaves Vol. 4; no. 1; pp. 147 - 157
• Main Authors: Chang, Shu-Ming, Swank, Chelsea, Kummel, Andrew, Buckwalter, James F.
• Format: Journal Article
• Language: English
• Published: IEEE 01-01-2024
• Subjects: Antenna measurements; Antennas; D-band; diamond composites; Diamonds; dielectric characterization; Dielectrics; free-space focused beam; Lenses; Material properties; Millimeter-wave; Permittivity; Thermal conductivity; time-domain gating
• ISSN: 2692-8388; 2692-8388
• DOI: 10.1109/JMW.2023.3339255

Compact millimeter-wave arrays demand novel packaging solutions that feature low-cost dielectric materials with significant thermal conductivity (<inline-formula><tex-math notation="LaTeX">\sim</tex-math></inline-formula>100 W/m ⋅ K). To characterize the permittivity and loss tangent of the dielectric materials above 100 GHz, free-space characterization is proposed to avoid de-embedding conductor losses. We review current approaches for characterization to investigate the properties of ultradense diamond composite materials at D-band. We compare free-space calibration multiple methods to extract the permittivity and loss tangent. Time-domain gating is employed to reduce the uncertainty in the free space characterization. Material characterizations of the dielectric constant and loss tangent include pure polymer TMPTA, PDMS, TMPTA-based, PDMS-based diamond composites as well as quartz and sapphire wafers for calibration from 120-160 GHz. To the author's knowledge, this is the first characterization of diamond composites for thermally conductive dielectric packaging requirements at D-band.