Measuring microwave properties of laminated dielectric substrates

Abstract

The theoretical approach is developed and the test rig is designed for measuring the microwave parameters of dielectric substrates at frequencies between 30 and 40 GHz and over a temperature range from −50 to +70°C. The test rig is based on sapphire resonators and allows the measurements of the following parameters of commonly used PCB materials: (i) dielectric constant (ε) of the dielectric substrate in the range from 2 to 10, (ii) loss tangent (tan δ) of the substrate in the range from 10−4 to 10−2, and (iii) ranging from 0.03 to 0.3 Ωsurface resistance of the laminating metal layer adjoining the dielectric material.

Analysis and design of efficient passive components for the millimeter-wave and THz bands

“…In these cases, in order to maintain low insertion losses, a good Q u is demanded, and the SSGW seems very suitable as it is less affected by the high dielectric losses at mmwave frequencies than other topologies such as SIW or the conventional transmission lines. Note also that for good dielectrics (acceptable values of tan δ in this sense have been measured at mm-wave frequencies [921]), the SSGW present competitive values of Q. Nevertheless, if the application is very demanding, a SSGW design can be easily mapped to a RGW design, which offers an outstanding performance since any dielectric loss is present.…”

“…The SIW vias are designed with diameter d = 0.3 mm and separation s = 0.6 mm, dimensions that have been chosen according to the Ka-band SIW literature [918]- [920] and with the aim to enhance the quality of the SIW resonator. The substrates permittivity is set to ε r = 2.25, taken from the Nelco NY922 substrate, a good quality reference one [921]. The loss tangent is parametrized to observe the influence of the dielectric quality on the losses.…”

“…The loss tangent is parametrized to observe the influence of the dielectric quality on the losses. In the case of the SSGW, the substrate thickness is set to t d = 127 µm which is a commercial standard value [921], whereas the SIW substrate is set to t d = 508 µm a standardized common value for the frequencies of interest [918]- [920]. a short-circuit cavity resonator.…”