Closed‐form and dispersive model considerations for relative permittivity extraction at millimetre‐wave frequencies

Abstract

This study provides a simple broadband method for determining the dielectric properties of laminate substrate materials used in integration and packaging solutions for commercial millimetre‐wave applications. Relative permittivity and loss tangent are extracted from coplanar lines using closed‐form equations that account for as‐fabricated transmission line dimensions. The method is applied to a low loss substrate alumina and further tested on glass impregnated epoxy resin materials with metals that have an appreciable metal surface roughness. The work expands existing material characterisation methods that are typically based on thin films. The dielectric substrates are thin, similar to integrated circuits, but the metal thicknesses remain on the order of packaging substrates. This study considers the critical parameters and manufacturing features for designs and millimetre‐wave material measurements on these types of materials. The method has an accuracy of within 10% of known values, utilises off‐the‐shelf software solutions when available, and requires no fixturing beyond the sample material. Error analysis is provided with material information on Isola FR408 up to 110 GHz.

Low-Cost and Small Size Millimeter Wave (24 Ghz) Extended Hemispherical Lens Antenna for Automotive and Industrial Applications Using Fr408hr Substrate

“…A few 24 GHz antennas have also been reported, but they are also designed on Rogers substrates and use expensive material for lens design. Recently, a published research article [9] reported the characterization of low-cost FR4 based substrates. According to this analysis, the FR408 substrate shows decent performance at 24 GHz, which was confirmed by calculating its electrical parameters by designing a ring resonator at 24 GHz on the FR408HR substrate.…”