Menu
Close
Close
Electromagnetic materials

Electromagnetic measurements on materials

Measurement of the dielectric permittivity and loss of low-, medium- and high-loss solids and liquids between 1 kHz and 100 GHz

Our facilities include:

Four coaxsen wg16spacer

  • Open-ended coaxial probes in various sizes for measurement on high-loss liquids and malleable solid materials in the frequency range 100 MHz to 50 GHz. These are typically used for measuring tissue-equivalent phantoms used in SAR (Specific Absorption Rate) measurement, foodstuffs, and biomedical materials. NPL-developed Monte-Carlo modelling software is used for evaluation of uncertainty. Measurement at lower frequencies (down to 30 MHz) on liquids is possible with coaxial cells and a 44-mm coaxial sensor. Measurements on layered materials is also possible.
  • Formulation and supply of phantoms for use in SAR measurement.
  • Coaxial line and waveguide transmission line measurements from 100 MHz to 18 GHz for medium to high-loss dielectrics and for relative permittivities up to 100. Coaxial cells based on 7 mm and 14 mm coaxial line are available. For waveguide measurement, spacers for a number of sizes (including X-band) are also available. For magnetic materials (e.g. ferrite RAM, ferroelectric composites) complex permittivity and complex permeability can both be determined.
  • Millimetre-wave open resonators for precise measurement on low-loss materials (ideally loss tangent < 0.003). Currently we have systems for approximately 36 GHz, 72 GHz and 94 GHz, and also a system for 8 GHz to 12 GHz.  
  • Dielectric resonator evaluation at microwave frequencies in a Courtney resonator or cylindrical cavity.
  • A selection of Split-Post Dielectric Resonators for measuring laminar materials at 1.8 GHz, 4 GHz, 8.2 GHz, 10 GHz and 14 GHz. Thin dielectric layers can be measured.
  • A number of microwave cavity resonator systems that allow measurements on rods and discs of material.
  • Re-entrant hybrid cavities that are used in the range 300 MHz to 1 GHz. These are typically used for measuring the loss of low-loss polymers and ceramics.
  • A Hartshorn and Ward resonant coil/capacitor system for measuring the loss of very low-loss materials with permittivity below 10 in the range 1 MHz to 70 MHz. The resolution for the measurement of loss tangent is approximately 0.00001.
  • Microwave by free-space quasi-optical methods at millimetre-wave frequencies.
  • Mapping of E-fields by using probing techniques, such as electrooptic sensors.

Contact us

Work with us

Our research and measurement solutions support innovation and product development. We work with companies to deliver business advantage and commercial success.
Contact our Customer Services team on +44 20 8943 7070