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Dielectric Constant, Strength, & Loss Tangent

Lossy dielectric equation for real and imaginary parts

QDielectricLoss = "Q" from dielectric loss equation - RF Cafe

Loss Tangent = Dielectric complex loss tangent - RF Cafe

Dielectric Loss = Dielectric loss equation - RF Cafe

Values presented here are relative dielectric constants (relative permittivities). As indicated by er = 1.00000 for a vacuum, all values are relative to a vacuum.

Multiply by ε0 = 8.8542 x 10-12 F/m (permittivity of free space) to obtain absolute permittivity. Dielectric constant is a measure of the charge retention capacity of a medium.

In general, low dielectric constants (i.e., Polypropylene) result in a "fast" substrate while large dielectric constants (i.e., Alumina) result in a "slow" substrate.

RF Cafe - Dielectric loss tangentThe dielectric loss tangent is defined by the angle between the capacitor's impedance vector and the negative reactive axis, as illustrated in the diagram to the right. It determines the lossiness of the medium. Similar to dielectric constant, low loss tangents result in a "fast" substrate while large loss tangents result in a "slow" substrate.

Dielectric complex conductivity - RF Cafe

Beware that the exact values can vary greatly depending on the particular manufacturer's process, so you should seek out data from the manufacturer for critical applications.

The dielectric constant can be calculated using:   ε = Cs / Cv , where Cs is the capacitance with the specimen as the dielectric, and Cv is the capacitance with a vacuum as the dielectric.

The dissipation factor can be calculated using:   D = tan δ = cot θ = 1 / (2π f RpCp) ,  where δ is the loss angle, θ is the phase angle, f is the frequency, Rp is the equivalent parallel resistance, and Cp is the equivalent parallel capacitance.

Note: All values can vary by very large amounts depending on the specific material. Check with the MatWeb.com website for more details. Other resources: Electrical Properties of Insulators, Dielectric Properties of Materials.

Substance Dielectric Constant

(relative to vacuum)

Dielectric

Strength

(V/mil)

Loss

Tangent

Max Temp

(°F)

ABS (plastic), Molded 2.0 - 3.5 400 - 1350 0.00500 - 0.0190 171 - 228
Air (STP, @900 kHz) 1.00058986 30 - 70    
Alumina - 96%

                - 99.5%

 

10.0

9.6

 

  0.0002 @ 1 GHz

0.0002 @ 100 MHz

0.0003 @ 10 GHz

 
Aluminum Silicate 5.3 - 5.5      
Bakelite 3.7      
Bakelite (mica filled) 4.7 325 - 375    
Balsa Wood 1.37 @ 1 MHz

1.22 @ 3 GHz

  0.012 @ 1 MHz

0.100 @ 3 GHz

 
Beeswax (yellow) 2.53 @ 1 MHz

2.39 @ 3 GHz

  0.0092 @ 1 MHz

0.0075 @ 3 GHz

 
Beryllium oxide 6.7   0.006 @ 10 GHz  
Butyl Rubber 2.35 @ 1 MHz

2.35 @ 3 GHz

  0.001 @ 1 MHz

0.0009 @ 3 GHz

 
Carbon Tetrachloride 2.17 @ 1 MHz

2.17 @ 3 GHz

  <0.0004 @ 1 MHz

0.0004 @ 3 GHz

 
Diamond 5.5 - 10      
Delrin (acetyl resin) 3.7 500   180
Douglas Fir 1.9 @ 1 MHz   0.023 @ 1 MHz  
Douglas Fir Plywood 1.93 @ 1 MHz

1.82 @ 3 GHz

  0.026 @ 1 MHz

0.027 @ 3 GHz

 
Enamel 5.1 450    
Epoxy glass PCB 5.2 700    
Ethyl Alcohol (absolute) 24.5 @ 1 MHz

6.5 @ 3 GHz

  0.09 @ 1 MHz

0.25 @ 3 GHz

 
Ethylene Glycol 41 @ 1 MHz

12 @ 3 GHz

  -0.03 @ 1 MHz

1 @ 3 GHz

 
Formica XX 4.00      
FR-4 (G-10) - low resin

                  - high resin

4.9

4.2

  0.008 @ 100 MHz

0.008 @ 3 GHz

 
Fused quartz 3.8   0.0002 @ 100 MHz

0.00006 @ 3 GHz

 
Fused silica (glass) 3.8      
Substance Dielectric Constant

(relative to vacuum)

Dielectric

Strength

(V/mil)

Loss

Tangent

Max Temp

(°F)

Gallium Arsenide (GaAs) 13.1   0.0016 @ 10 GHz  
Germanium 16      
Glass (Corning 7059) 5.75   0.0036 @ 10 GHz  
Glass (lead silicate) 7 - 14   (Table 2: LS30-LS32)  
Glass, Crushed / Powdered (Corning 7070) 4.6   0.000600 924
Gutta-percha 2.6      
Halowax oil 4.8      
High Density Polyethylene (HDPE), Molded 1.0 - 5.0 475 - 3810 0.0000400 - 0.00100 158 - 248
Ice (pure distilled water) 4.15 @ 1 MHz

3.2 @ 3 GHz

  0.12 @ 1 MHz

0.0009 @ 3 GHz

 
Kapton® Type 100

            Type 150

3.9

2.9

7400

4400

  500

 

Kel-F 2.6      
Lexan® 2.96 400   275
Lucite 2.8      
Mahogany 2.25 @ 1 MHz

1.88 @ 3 GHz

  0.025 @ 1 MHz

0.025 @ 3 GHz

 
Mica         

Mica, Ruby

4.5 - 8.0

5.4

3800 -5600    
Micarta 254 3.4 - 5.4      
Mylar® 3.2 7000   250
Neoprene 6 - 9 600    
Neoprene rubber 6.26 @ 1 MHz

4 @ 3 GHz

  0.038 @ 1 MHz

0.034 @ 3 GHz

 
Nomex®   800   450
Nylon 3.2 - 5 400   280
Oil (mineral, squibb) 2.7 200    
Paper (bond) 3.0 200    
Paraffin 2-3      
PEEK™ 450G Polymer (@23 °C, 100 MHz) 3.2 ~900 0.003  
Phenolica (glass-filled) 5 - 7      
Phenolics (cellulose-filled) 4 - 15   0.03 @ 100 MHz  
Phenolics (mica-filled) 4.7 - 7.5      
Plexiglass® 2.2 - 3.4 450 - 990    
Polyethylene LDPE/HDPE 2.26 @ 1 MHz

2.26 @ 3 GHz

450 - 1200 0.0002 @ 100 MHz

0.00031 @ 3 GHz

170
Polyamide 2.5 - 2.6      
Polycarbonate, Molded 2.8 - 3.4 380 - 965 0.000660 - 0.0100 239 - 275
Polypropylene 2.2 500   250
Polystyrene 2.5 - 2.6 500 0.0001 @ 100 MHz

0.00033 @ 3 GHz

 
Polyvinylchloride (PVC) 3 725   140
Porcelain 5.1 - 5.9 40 -280    
Pyrex glass (Corning 7740) 5.1 335    
Substance Dielectric Constant

(relative to vacuum)

Dielectric

Strength

(V/mil)

Loss

Tangent

Max Temp

(°F)

Quartz (fused) 4.2 150 - 200    
RT/Duroid 5880

(go to Rogers)

2.20      
Rubber 3.0 - 4.0 150 - 500   170
Ruby 11.3      
Silicon 11.7 - 12.9 100 - 700 0.005 @ 1 GHz

0.015 @ 10 GHz

300
Silicone oil 2.5      
Silicone RTV 3.6 550    
Soil (dry sandy) 2.59 @ 1 MHz

2.55 @ 3 GHz

  0.017 @ 1 MHz

0.0062 @ 3 GHz

 
Soil (dry loamy) 2.53 @ 1 MHz

2.44 @ 3 GHz

  0.018 @ 1 MHz

0.0011 @ 3 GHz

 
Steatite 5.3-6.5      
Strontium titanate 233      
Teflon® (PTFE) 2.0 - 2.1 1000 0.00028 @ 3 GHz 480
Tefzel® (1 kHz - 3 Ghz) 2.6 - 2.3   0.0007 - 0.0119 300
Tenite 2.9 - 4.5      
Transformer oil 4.5      
Vacuum (free space) 1.00000      
Valox®   1560   400
Vaseline 2.16   0.00004 @ 0.1 GHz

0.00066 @ 3 GHz

 
Vinyl 2.8 - 4.5      
Water (32°F)

         (68°F)

          (212°F)

88.0

80.4

55.3

80 0.04 @ 1 MHz

0.157 @ 3 GHz

 
Water (distilled) 76.7 - 78.2   0.005 @ 100 MHz

0.157 @ 3 GHz

 
Wood 1.2 - 2.1   0.04 @ 0.1 GHz

0.03 @ 3 GHz

 
 

Supplemental information provided by website visitor James S. for complex dielectric:

The dielectric constants at the top of [this] page are reminiscent of the propagation constants given by Roald K. Wangsness, Electromagnetic Fields, 2nd Ed., John Wiley & Sons, New York, 1986, p. 383, Eq. (24-42) and (24-43). The sixth equation given on the web page is correct. That equation, as given by P. Hoekstra and A. Delaney in Dielectric properties of soils at UHF and microwave frequencies, J. Geophys. Res., v. 79, 10 Apr 1974, p. 1699, "... is written as

      K*(ω) = K'(ω) - iK"(ω) , where

           K'(ω) is the dielectric constant and

           K"(ω) is the dielectric loss factor.

Hence, Complex Dielectric Constant at High Frequencies - RF Cafe

Related Pages on RF Cafe

- Coaxial Cable Specifications

- Capacitor Dielectrics & Descriptions

- Dielectric Constant, Strength, & Loss Tangent

- Conductor Bulk Resistivity & Skin Depths

- Coaxial Cable Equations

- Coaxial Cable Specifications

- Coaxial Cable Vendors

- Coaxial Resonator

- Skin Depth Calculator

- Coaxial Connector Usage Chart

Note: Thanks to Gareth for correcting the omission of a square root sign in the dielectric equations.

          Thanks to Craig B. for correcting the loss tangent for Teflon (0.00028 rather than 0.0028).

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