Electromagnetic Material Characterization: Dk & Df Testing Services
Accurately measure dielectric constant (Dk) and loss tangent (Df) of your materials, with 5-business-day standard turnaround and rush service available.
iEMSL measures the dielectric constant (Dk) and loss tangent (Df) of solid materials from 8.2 to 52.2 GHz using three complementary methods: WR-90 waveguide transmission line, split-post dielectric resonator (SPDR), and Fabry-Perot open resonator (FPOR). Dielectric-constant accuracy reaches ±0.25%, and testing is available at room temperature or up to 100 °C. Pricing starts at $300 per sample.
The Intelligent Electromagnetic Sensor Laboratories (iEMSL) at Texas A&M University, in collaboration with QWED and Warsaw University of Technology, offers specialized material characterization services. We precisely evaluate how materials interact with electromagnetic fields, providing critical data on their properties to support researchers and industries in advanced design and innovation.
Our Core Capabilities & Instrumentation
We precisely measure fundamental electromagnetic properties of materials, including complex permittivity (ϵ=ϵ′−jϵ′′), which comprises the dielectric constant (dk or ϵr′ or K) and the loss tangent (df or tanδ=ϵ′′/ϵ′), as well as shielding effectiveness.
We specialize in the characterization of solid dielectrics and semiconductors, which are foundational to modern electronics, acting as insulators in capacitors, substrates for printed circuit boards, and critical high-frequency components. Accurate analysis of their electrical properties is vital for product development, quality control, and advanced material selection.
What We Measure: Material Categories and Capabilities
Solid Dielectrics
We characterize insulating materials essential for high-frequency electronics.
- Parameters: Dk (Dielectric Constant), Df (Loss Tangent)
- Frequency Coverage: 8–52.2 GHz (method-dependent)
- Methods: WR-90 8-12 GHz, SPDR 10 GHz, FPOR 10–52.2 GHz
Semiconductors
Measurements focused on characterizing bulk and surface conductivity.
We can also measure film on film-on-substrate coatings.
- Parameters: Dk (Dielectric Constant), Df (Loss Tangent),
σ (Conductivity), ρ (Resistivity), Rs (Sheet Resistance, Ω/sq) - Frequency Coverage: 10 GHz
- Methods: SPDR 10 GHz
Measurement Systems Overview
Our measurements utilize advanced Keysight PNA-X (up to 26.5 GHz) and Rohde & Schwarz ZVA (up to 67 GHz) vector network analyzers. By combining industry-leading commercial software with our specialized tools, we ensure precise control and extraction of critical material parameters, tailored to your specific requirements.
Our services leverage three primary measurement systems, each optimized for specific material types and frequency ranges. Refer to the table below for a quick comparison:
WR-90 Waveguide Transmission Line
Frequency Range:
8.2 – 12.4 GHz (X-Band)
Sample Requirements:
Length: 22.81 mm, Width: 10.11 mm (slip fit),
Thickness: 1-9.7 mm. Three thicknesses recommended.
Temperature:
Room to 100°C
Application & Specs:
Supporting the ASTM D5568−22a standard, this broadband technique, best for lossy or medium loss MUTs and machineable solids. It allows high-precision characterization of solid material, measuring dielectric constant (ε’) and loss tangent (tan δ).
Permeability and Shielding Effectiveness (SE) can also be tested (Custom).
For more information and pricing
Split Post Dielectric Resonator (SPDR)
Frequency:
10 GHz
Sample Requirements:
Length: > 45 mm, Width: 45 – 90 mm, Thickness: 15 µm – 0.95 mm
Planar samples with clean edges
Temperature:
Room to 100 °C
Application & Specs:
Supporting the IPC 2.5.5.15 and IEC 61189-2-721 standards, this resonator based method is ideal for accurate characterization of thin dielectrics. Provides the highest sensitivity and ultra-high accuracy for measuring extremely low-loss materials. Essential for characterizing ceramics and specialized polymers used in high-Q resonant structures. Characterizes film-on-substrate coatings.
For more information and pricing
Fabry-Perot Open Resonator (FPOR)
Frequency Range:
10.2 – 52.2 GHz
Sample Requirements:
Diameter: 75 – 110 mm (101–109 mm for full range), Thickness: 1 µm – 3 mm
If anisotropic, specify in-plane axes
Temperature:
Room Temperature
Application & Specs:
Ideal for non-destructive, non-contact testing of large, flat material samples (e.g., substrates, composites). Offers high Q factor measurements across a wide frequency spectrum. Characterize in-plane anisotropy of dielectric sheets, polymers, glasses.
For more information and pricing
More details are provided below:
► WR-90 Waveguide Transmission Line (8.2 -12.4 GHz)
For solid, homogenous materials, the iEMSL can measure the complex permittivity (±5% accuracy) in the 8.2 – 12.4 GHz (X-band) range.
The iEMSL utilizes the PNA-X Vector Network Analyzer for S-parameter extraction, and a Nicholson-Ross-Weir extraction algorithm script to visualize your material’s response supporting the ASTM D5568 standard. You must provide a solid material matching the provided waveguide dimensions..
Samples must have rectangular dimensions of 22.81 mm x 10.11 mm, with a thickness of 1–9.7 mm.
Measurement limitations to be aware of:
The transmission line method has inherent thickness sensitivities. The Nicolson-Ross-Weir algorithm has known divergence behavior at certain sample thicknesses (integer multiples of the in-material half-wavelength), which depends on the material’s dielectric constant. Df measurement accuracy also depends on sample thickness: low-loss materials need enough thickness to produce measurable attenuation, while high-loss materials need thin enough samples to keep the transmitted signal above noise. Because the optimal thickness depends on properties you may not know in advance, we strongly recommend submitting multiple sample thicknesses.
Recommended submission:
Provide three samples of the same material at different thicknesses. This lets us cross-check the measurement, avoid NRW divergence regions, and select the optimal thickness for both Dk and Df extraction.
| Material class | Suggested thickness set (mm) |
|---|---|
| Unknown / general purpose | 2, 4, 6 |
| Low-loss polymers (PTFE, PE) | 3, 5, 7 |
| Standard polymers, FR-4 substrates | 2, 3.5, 5 |
| High-Dk ceramics or filled composites | 1.5, 2.5, 4 |
| Lossy / carbon-loaded / absorbers | 1, 1.5, 2 |
If only one sample is available, we accept single submissions but Df accuracy is reduced and the result will be flagged if the thickness happens to land near a divergence region.
Accuracy:
- Dielectric constant (Dk): ±5%
- Loss tangent (Df): ±5% above 1 × 10⁻³, larger below
- Shielding effectiveness: ±1%
Price per Sample:
- Room Temperature: $300 first + $200 additional
- Up to 100°C: $500/sample
What you receive:
- Extracted Dk and Df
- Charts and tables (vs frequency and/or temperature as applicable)
- Raw data (Touchstone files) on request
- Technical Report on request (for extra charge)
View our example measurements.
► Split Post Dielectric Resonator (10 GHz) – in collaboration with QWED
The split post dielectric resonator (SPDR) measures the dielectric constant (Dk) and loss tangent (Df) of thin dielectric sheets. Samples must be planar, with lateral dimensions of 45–90 mm (length ≥ 45 mm, width 45–90 mm) and a thickness between 15 µm and 0.95 mm.
Utilizing the PNA-X Vector Network Analyzer, the iEMSL offers single frequency measurements of the dielectric constant at 10GHz with the SPDR. Supporting the IPC 2.5.5.15 and IEC 61189-2-721 standards, this resonator based method is ideal for accurate characterization of thin dielectrics. The measurement accuracy for Dielectric constant: is Δε/ε = ±(0.0015 + Δh/h) and for Loss tangent: Δtanδ = ±2×10⁻⁵ or ±0.03*tanδ (higher of the two). For more information, visit QWED.
Price per Sample:
- Room Temperature: $300 first + $200 additional
- Up to 100°C: $500/sample
What you receive:
- Extracted Dk and Df
- Tables (vs temperature as applicable)
- Raw data (CSV) including resonance/Q data on request
- Technical Report on request (for extra charge)
View our example measurements.
► Fabry-Perot Open Resonator (10.2 – 52.2 GHz) – in collaboration with QWED
iEMSL utilizes the ZVA67 Vector Network Analyzer along with the FPOR to offer very high precision for dielectric constant (±0.25%) and loss tangent (±2%) measurements over the wide frequency band of 10.2 – 52.2GHz, the FPOR is ideal for a wide variety of measurements and precision needs. This also enables In-plane anisotropy testing and climatic compensation is always enabled. Samples should have a diameter between 75 mm and 110 mm and a thickness between 1 µm and 3 mm. The measurement accuracy for Dielectric constant: is ±0.25% (for Dk = 1 – 15) and for Loss tangent: tanδ < 10, ±2% (for Df >5×10⁻⁶).
Thickness & Dk Limitations
This graph illustrates the relationship between a material’s dielectric constant (Dk) and its thickness, defining the measurable and unmeasurable regions for a specific testing method. The green and tan areas represent valid combinations that can be measured, while the two “prohibited zones” indicate combinations that cannot be reliably tested. For Dk < 3, the maximum thickness is 3mm.
- Green Zone: This is the ideal measurement range, where combinations of Dk and thickness allow for highly reliable and precise results with a low measurement uncertainty of ±0.25%.
- Tan Zone: This area indicates that a measurement can still be obtained, but with a greater uncertainty of ±0.5%.
- Prohibited Zones: These zones represent invalid combinations of Dk and thickness where no reliable data can be acquired.
Thickness & Df Limitations
Limitations are imposed on the maximum loss tangent with respect to thickness. If the material has a very high loss, the resonator curve may not be distinguishable from noise.
Dimension Requirements
To achieve the full frequency range down to 10.2 GHz, the target sample size should be between 101 mm and 109 mm. For rectangular samples, one dimension can be up to 150 mm, but the other must be less than 110 mm.
Room Temperature Pricing (Per Sample):
We measure in four frequency bands across 10.2 to 52.2 GHz, each about 10 GHz wide. Request any single band or the full range, at your choice of precision.
| Precision | Price per band | Frequency points per band | Full range (4 bands) |
|---|---|---|---|
| Basic | $500 | 4 | $2,000 |
| Advanced | $800 | 8 | $3,200 |
Frequency bands: Band 1 (10.2 to 20.7 GHz), Band 2 (20.7 to 31.2 GHz), Band 3 (31.2 to 40.2 GHz), Band 4 (40.2 to 52.2 GHz).
Axis Configurations
- Single-Axis: Standard testing included in the base pricing above.
- Dual-Axis (Orthogonal): Measures in-plane anisotropy by running a second measurement cycle. Because this requires a full second cycle, it is billed as an additional sample.
What you receive:
- Extracted parameters (Dk, Df)
- Charts and tables vs frequency
- Raw data (CSV) including and resonance/Q data on request
- Technical Report on request (for extra charge)
View our example measurements.
Summary
| Measurement System | Frequency Range | Applications | Sample Requirements | Price per Sample |
|---|---|---|---|---|
| Transmission Line WR-90 Waveguide |
8.2 – 12.4 GHz (X-band) |
Permittivity & Loss tangent for machineable solids Supports the ASTM D5568−22a standard |
Length: 22.81 mm Width: 10.11 mm Thickness: 1–9.7 mm |
Room Temperature: $300 first + $200 additional Up to 100°C: $500/sample |
| Split Post Dielectric Resonator (SPDR) |
10 GHz | Complex permittivity of dielectric sheets Supports IPC 2.5.5.15 & IEC 61189-2-721 standards Characterizes film-on-substrate coatings by tracking tiny shifts in resonance frequency and Q-factor |
Length: > 45 mm Width: 45 – 90 mm Thickness: 15 µm – 0.95 mm |
Room Temperature: $300 first + $200 additional Up to 100°C: $500/sample |
| Fabry-Perot Open Resonator (FPOR) |
10.2 – 52.2 GHz | Wideband complex permittivity In-plane anisotropy of dielectric sheets, polymers, glasses Characterizes film-on-substrate coatings |
Diameter: 75–110 mm (101–109 mm for full range; 105 mm ideal) Thickness: 1 µm – 3 mm (Thinner is better) |
Room Temperature: Basic: $500/band (4 points) Advanced: $800/band (8 points) Full range (4 bands): $2,000 / $3,200 |
Custom Solutions
Beyond our standard services, we provide specialized characterization tailored to unique material needs and extreme operating conditions. While our standard offerings provide foundational data, our custom suite extends from ultra-low frequencies (3 µHz) to high-microwave (20 GHz) regimes, featuring rare thermal capabilities from -160°C up to 400°C. This flexibility allows us to accurately characterize complex conductors, ferromagnetics, absorbers, and liquids.
We offer the following specialized methodologies:
- Broadband Dielectric Spectroscopy (3 µHz – 20 MHz): High-sensitivity analysis of permittivity (ϵr′) and loss tangent (tanδ) across extreme temperature gradients (-160°C to 400°C).
- Keysight High-Temperature Dielectric Probe Kit (200 MHz – 20 GHz): Optimized for in-situ measurements of both solids and liquids at temperatures up to 200°C.
- X-Band Magnetic Characterization (8.2 – 12.4 GHz): Precise measurement of complex permeability (μr) for ferromagnetic materials and absorbers, supporting the ASTM D5568-22a standard.
- Shielding Effectiveness (SE) Analysis: Quantitative evaluation of EMI/RFI attenuation for conductive and composite materials within the WR-90 waveguide range.
Reach out, and we’ll strive to accommodate your specific research or industrial request with our flexible, innovative approach.
Frequently Asked Questions
► What is the difference between dielectric constant (Dk) and loss tangent (Df)?
Both come from a material’s complex permittivity, ε = ε′ − jε″. The dielectric constant (Dk, εr′) is the real part: how much electromagnetic energy the material stores. The loss tangent (Df, tanδ = ε″/ε′) is the ratio of energy dissipated to energy stored, i.e. how lossy the material is at a given frequency. Low-loss substrates for high-frequency electronics need both a stable Dk and a low Df.
► Which measurement method is right for my material?
It depends on your sample and frequency range. The WR-90 waveguide transmission line (8.2–12.4 GHz) suits machineable solids and supports ASTM D5568-22a. The split-post dielectric resonator (SPDR) gives the highest accuracy for thin, low-loss sheets at a single 10 GHz point. The Fabry-Perot open resonator (FPOR) covers the widest band (10.2–52.2 GHz) for large, flat samples and is the method for in-plane anisotropy. If you are unsure, request a quote describing your material, and we will recommend a method.
► What industry standards do your measurements support?
The WR-90 waveguide method supports ASTM D5568-22a. The SPDR method supports IPC 2.5.5.15 and IEC 61189-2-721.
► How much does dielectric testing cost?
WR-90 and SPDR measurements start at $300 for the first sample plus $200 per additional sample at room temperature, or $500 per sample up to 100 °C. FPOR measurements start at $500 per frequency band (basic) or $800 per band (advanced), with the full 10.2–52.2 GHz range at $2,000 (basic) or $3,200 (advanced). TAMU researchers receive a 50% reduction. See the summary table above for full pricing.
► How do I submit a sample for testing?
Start by submitting a request through the Request a Quote form with your material type, target frequency range, and quantity. Prepare samples to the dimensions listed for your chosen method above. For the WR-90 method we recommend submitting three thicknesses of the same material for the most reliable Dk and Df extraction.
► What is your turnaround time?
Standard turnaround is 5 business days from receipt of your sample. Rush service is available for time-critical projects. Just request a quote and tell us your deadline.
Ready to Measure?
iEMSL is equipped to support your material electrical testing needs. Click below to submit a request to have your material evaluated in our state-of-the-art facilities.