Specialty Glass for High-Frequency Applications
The requirements for materials in the high frequency market are very challenging and complex. Due to the shift towards higher and higher frequency bands, the dielectric properties and processing precision become extremely important. Consequently, the typically used materials like polymers and ceramics are subjected to a constant material development process. SCHOTT has a broad portfolio of glasses that are suitable for high-frequency applications, with the ideal combination of properties for this demanding area.
The high purity/homogeneity of glass results in almost zero density fluctuations. In contrast, ceramics dielectrics have pores from sintering leading to density variations with local shifts in DK (dielectrical constant) value. The resulting natural frequency cannot be met precisely enough to reliable met the desired frequency from the device. Moreover, our glassportfolio offers a broad range of dielectrical properties (dielectric constant and loss tan values) which can be combined with certain CTE (coefficient of linear thermal expansion) levels for an individual product design. Unlike polymers, which have a high surface roughness, glass is supremely smooth with root mean square values (RMS) of 1 nm and below. This enables metallization and smooth metal coatings with ideal electrical performance of metal layers with low energy losses due to absence of scattering. Another important parameter at high frequencies is the processing precision. In contrast to polymers and ceramics, glass can be processed in the µm range what enables specified frequency characteristics. Various shapes like rods, discs and tubing are available on request. Low temperature coefficients together with exceptional heat resistance (0 - 950 Kelvin) also make them suitable for a range of environments – even space.
The ideal antenna material
One of the most exciting areas of telecoms is 5G. This new generation of mobile communication requires a global network of high-frequency antennas made of highly efficient and specialized materials. These materials require specific physical properties to withstand the harshest environments, including space.
Discover how specialty SCHOTT glass leads to low dielectric loss and improved communications performance.
The shape of things to come
For efficient wavelength detection, the latest high-frequency antennas are made using components with accurate and complex shapes. For many materials, this can present a problem, but glass has the ability to be precisely processed in a vast range of forms to suit highly specific shapes. Taken with its superior physical properties, this gives the material a huge advantage in the communications industry.
The best glass for the job
We compared the relative permittivity and dielectric loss factor of SCHOTT 8252 glass to DURAN® glass tubing and found the following results. While DURAN® glass tubing shows a lower dielectric constant, SCHOTT 8252 shows a lower dielectric loss. Therefore, which glass you use depends on the requirements of your application.
High Precision Dielectric Characterisation (ɛ, tan(δ)) at 1.1, 1.9, 5, 10 and 15 GHz Microwave Frequency
|f0 [GHz]||Relative permittivity
|DURAN®||SCHOTT 8252||DURAN®||SCHOTT 8252|
- Split Post Dielectric Resonator (SPDR) at 25° C
Wall thickness samples
- 1.1 GHz, 1.9 GHz: ca. 1 mm
- 5 GHz, 10 GHz, 15 GHz: ca. 0.5 mm
DURAN® is a registered trademark of DWK Life Sciences GmbH.
Additional material properties of suitable glass types*
|Glass types||Coefficient of mean linear thermal expansion α (20°C; 300°C) (ISO 7991) [10-6 K-1]||Dielectric loss factor tan δ [10-4] at 1 MHz||Dielectric constant ε||Transformation temperature Tg (ISO 7884-8)|
*Excerpt of our glass portfolio, more information on request
The ideal properties for high-frequency applications
Dr. Christoph Bäumler
Product Manager Technical Tubing