EpsiMu : A New Microwave Materials Measurements Kit. - SEE

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and studies versus temperature, etc). The standardcell is around 144 mm long. The outer diameter is7 mm. Connectors are of the type PC7. Thedimensions determine the frequency range, thehighest frequency is over 19 GHz. We fixfrequency range from 1GHz to 18GHz.Two coaxial cells and a sample of a testmaterial are shown in the first photograph. One ofthe cells is taken apart to view all the componentsof the cell.Photograph 2: EpsiMu kitOuter conductorInner conductorPhotograph 1: Coaxial cellThis cell is characterised with its electricaldistances from the reference phase planes and withits attenuation. These characteristics form theIdentity Card. Each cell must be measured todetermine its ''Identity Card''. Knowing thesecharacteristics, the de-embedding technique can beperformed.3.2. Associated SoftwareThe software of EpsiMu is not restricted to aparticular VNA. In fact, any analyser could beused with EpsiMu. Tests were performed withAgilent 8510 and 8720 family, Anritsu MS462xfamily and Rodhe & Schwarz ZVR or ZVM.However, it is assigned to one particular cellversus its Identity Card. This sowftare have twoparts: the first part performs measurements in realtime. This is the “Epsilon-meter”. The second partis used post-treatments, for example, visualisation,comparisons of several results, etc.Nowadays, the software is in its first version,but a new one is under preparation to proposegreater possibilities, like a linearization of results,or visualisation of Cole-Cole diagram, etc.3.3. EpsiMu KitTest samplesWe show the complete kit in the secondphotograph. It contains one measurement cell,some accesories to make and verify materialssamples and one CD, containing the associatedsoftware, the measurement guide and some data toverify the kit. In addition, a sample of thereference material is in the kit.43214. ResultsTo illustrate the performance of this new kit,we chose several particular materials: adielectric material (polyethylene), a magneticmaterial (Emerson and Cuming SF10) and airsample.At first, we can verify if the measurementswith EspiMu, are correct by using thevisualisation of the S-parameters of the sample.In particular, we can determine if the sample istoo long or manufactured not perfectly.Second, we can proceed to measurements inreal time. The result of these measurements areshown in the next figures.4.1. Dielectric Material: PolyethyleneThe thickness of the sample is 1.85mm. Fourcurves are plotted on these graphics presentingpermittivity and permeability, two for the realparts (forward and reverse measurements withVNA) and two for the imaginary parts.Dielectric permittivity00.00 5.00 10.00 15.00frequency (GHz)ε''Figure 1:Polyethylene : permittivityε'author: P. SabourouxETTC 2005 – European Test & Telemetry Conference
10µ''0.00.00 5.00 10.00 15.00frequency (GHz)864202.01.51.00.532.521.510.50Permeability4.2. Magnetic Material: SF10This material is magnetically-loaded,electrically non-conductive silicone sheet. It ismanufactered by Emerson and Cuming. The truethickness of the test sample is 1.8mm (the nominalthickness given by the manufactured is 1.4 mm).We can verify in figure 2 that this material ismagnetic because the real part of its permeabilitydiffers from unity. The black curves are obtainedwith foward measurements with VNA (S 11 and S 21 )and the grey curves are obtained using reversemeasurements (S 22 and S 12 ).µ'Figure 2: Polyethylene: permeabilityµ''Permeabilityµ'ε'ε''0 5 10 15frequency (GHz)Figure 3: SF10 : permittivityµ''Dielectric permittivityµ'ε'0 5 10 15frequency (GHz)ε''Figure 4: SF10 : permeabilityepsilon'epsilon'4.3. AirTo test the kit, we measure an empty celllike an air-line. The thickness is not defined. So,we can choose any values to demonstrateseveral phenomena. In the same figure 3 a samegraphic (figure 3), four curves are ploted withfour arbitrary values of thickness: 3, 4, 5 and6mm. All results are superposed, as could beexpected.The results for the other three parameters areidentical (ε”≈ 0, µ’ ≈1 and µ’’ ≈0).1.510.50Dielectric permittivity8 10 12 14 16 18frequency (GHz)Figure 5: test with empty cellThe choice of sample thickness is veryimportant because, a jump will appear when thethickness is higher than λ mat /2. And indeed, for athickness equal to 9mm of the same virtual airsample, the jump appears at 16.6GHz (figure 4).21.510.50-0.5-13mm4mm5mm6mm3mm9mm8 10 12 14 16 18frequency (GHz)Because of this jump, when using the firstversion of EpsiMu, the thikness of samples mustbe lower than λ mat /2. In the next version of thesoftware, we shall take into account thesejumps.The accuracy of measurements is around±3% and ±10% depending on values ofpermittivity and permeability constants and onthe nature of material.ε'ε'Figure 6: Choice of thickness (test with anempty cell)author: P. SabourouxETTC 2005 – European Test & Telemetry Conference
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