Vector network analyzer

The dielectric constant (6r) and the quality values Q at microwave frequency were measured using the Hakki-Coleman s dielectric resonator method , and modified and improved by Courtney. A vector network analyzer (E8363, Agilent Technologies, Loveland, CO, USA) was employed in the measurement. The temperature coefficient of resonant frequency (t/) was measured in the temperature range from -25 to h-85 °C. The X/ value was defined as follows ... 

The thermal conductivity was determined by laser-flash method (LFA447, Netzsch, German) with billets dimension of (pl2.7mmx2.5mm. The dielectric loss (land) was measured at IMHz by the perturbation meth(xl using a cavity resonator and a vector network analyzer (HP-4294A). 

For RF measurements, another class of instruments is available. Modem high-end network analyzers range up to 110 GHz. These instmments use reflexion measurements to determine ratios of inserted to reflected power. Because of the use of directional couplers, the lower frequency limit will typically not go below a few kHz. To obtain complex impedance values, a vector network analyzer (VNA) is needed, because scalar network analyzers give absolute values only. Measurements can be conducted very fast... 

There are scores of microwave devices that need to be measured. The most common measurements tirat are done are the frequency measurements, but we are also interested in phase measurements depending on the device under test (DUT). We can use various equipments like spectrum analyzer, vector network analyzer, etc. [33]. Most of the devices that we measure will be two-port devices that is, the input is applied at one port and the output is taken at the other port. So we will basically be measuring devices, a group of devices that form a part of tiie system, and microwave circuits. 

Therefore, to characterize DUT on a wafer basically involves two steps (1) vector network analyzer (VNA) calibration and (2) calibration substrate. 

Rolfes, I. and Schiek, B., LRR-a self-calibration technique for the calibration of vector network analyzers, IEEE Transactions on Instrumentation and Measurement, Vol. 52, No. 2, April 2003, p>p. 316-319. 

Network analysis (6.3.3) 100 MHz-10 GHz Both reflected wave and wave transmitted through sample are analyzed in terms of phase and amplitude using common network analyzers High precision attained for materials of sufficient conductivity and dielectric strength The Rhode Schwarz ZVRE vector network analyzer in combination with a dielectric sample holder and a compatible temperature system... 

Network analyzers Rohde Schwarz R S ZVA 20 kHz-8 GHz 0.1-10 3 X 10- or 10- Vector network analyzer... 

Agilent HP 4396B 100 kHz-1.8 GHz 2-5 X 10 — Vector network analyzer (measurement technique RF I/V)... 

Rohde Schwarz R S ZVRE 300kHz GHz — — Vector network analyzer (production discontinued)... 

The capacitance of the sensor for the variation of pH obtained from a Vector Network Analyzer (VNA) at KXlMHz is shown in Fig. 7.7. From the figure, the capacitance at pH 1.0 is 7.84pF that increases by approximately five times and reaches 37.41 pF at pH 5.0. For lower pH, higher concentration of H+-ions produces lower diffuse-layer capacitance due to higher local electric fields that orient the water molecules in its directions. At very high frequencies, the inductive reactance becomes dominant over the capacitive reactance, hence, the operating frequency of the sensor is kept below KXlMHz. 

Figure 7.7 The capacitance of the sensor for pH ranging from 1.0 to 5.0 obtained from Vector Network Analyzer (VNA) at 100 MHz. In the inset, the capacitance of the sensor for pH ranges from 3.0 to 5.0.

The permittivity of Fe203 was measured using the cavity perturbation technique [17]. The main components of the measurement system include a resistive heating furnace and a cylindrical TMort) resonant mode cavity. The system measures the differences (frequency shift and change of quality factors) in the microwave cavity response between a cavity with an empty sample-holder and the same cavity with a sample-holder plus the sample at each specified temperature. These differences are recorded in a Hewlett Packard 8753B vector network analyzer and then used to calculate the permittivity. The details about this technique and apparatus used for the measurements can be found in the published literature [17,18]. 

The measured sheet resistance of the silk screen pattern on the fabric (cotton) ranges between 0.01 and 60 mO/m, as measured by a standard four-point probe. This value remains unchanged after 50 washing cycles (Kim et al., 2010). The resistance measurement yielded results of the proposed via and conductive adhesive and the frequency response of a P-FCB transmission Une (15 cm long and 1mm wide). Its bandwidth is 80 MHz, and this is sufficient to deal with biosignal processing. The analyses were performed with a vector network analyzer (Lee et al., 2010). To get an average value, as many as 100 connections were formed and measured. The resistances of the proposed via and conductive adhesive measured 0.24 and 0.34 W, respectively (Kim et al., 2010). 

Experimentally, the shielding effectiveness of the nanocomposites is typically measured using network analyzer instruments. Scalar network analyzer (SNA) only measures the amplitude of signals whereas vector network analyzer (VNA) measures both amplitude and phase properties. 

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