Using an impedance analyzer, you can measure the complex electrical impedance of a component. The analyzer will then measure the impedance as a function of the test frequency. You can also use it to analyze scattering parameters between ports in a multi-port network.
Bioelectrical impedance analysis (BIA)
BIA is a simple non-invasive method to measure body composition. The results are obtained by measuring resistance and current flow in the body. It is used to identify differences between body fat and non-fat mass. The results are highly reproducible and can be used to track changes in body composition.
The first impedance analyzer was developed by French physician Thomasset in 1962. Thomasset believed that electrical resistance could reflect the fluid content of the human body. In clinical medicine, he introduced the use of bioelectric impedance analysis to estimate body fat and lean body mass.
BIA is one of the most common body composition measurement techniques. It is a non-invasive test that can be performed at home. It has gained popularity because of its accuracy and ease of use.
In 1962, Thomasset and his colleagues introduced the first impedance analyzer to clinical medicine. They used two electrodes to measure the current and resistance of the body. They believed that a simple technique could help doctors determine body fat and lean body mass.
Measurement of complex impedance between a pair of terminals
Getting the complex impedance of a pair of terminals is easy using a simple electronic circuit. A complex representation of the sinusoidal voltage between two terminals is the impedance. The impedance can be measured by a combination of the observed voltages and the circuit’s magnitude.
A simple electronic circuit can automatically produce the first order phase angle to calculate the impedance of a pair of terminals. For the most part, this is the easiest measurement to make.
The complex impedance of a pair of circuit terminals is measured by combining the voltages corresponding to the observed standing wave data. A similar approach can be used to calculate the magnitude of the various resistive components of a circuit element. The measuring circuits of the present invention can measure inductive and capacitive reactances.
The measuring circuits of the present invention are capable of generating the appropriate signals using current summing means and detecting means. Various reference circuit elements may be used.
Measurement of scattering parameters between ports in a multi-port network
Several papers have been published on the topic of measurement of scattering parameters between ports in a multi-port network. These papers address the various aspects of the method. However, there is no general method for measuring scattering parameters of an N-port device with a two-port network analyzer.
In general, an RF signal incident on one port can be reflected back to the incident port. The reflected power waves can be interpreted as either heat or electromagnetic radiation. However, in some cases, the power waves can disappear as the incident signal moves.
The S-matrix or scattering parameter is a mathematical representation of energy propagation in a multi-port electrical network. It describes the network in terms of amplitude, phase, frequency, and reflection coefficients. It can also be expressed in a logarithmic form. These parameters are typically measured with a Vector Network Analyzer. The S-matrix is commonly recorded in a csv file. The measured S-parameters can then be imported into RF Toolbox, or other RF toolbox software.
Self-calibration
During the self-calibration process of an IM&TE instrument, the measurement ranges are verified to ensure the instrument is within the published specifications. This verification is achieved by performing self-test procedures. The ranges can be measured at the probe tip or the coaxial cable end. The main parameters are then recorded on the SD memory card.
Depending on the requirements of your application, the process of self-calibration may be performed fully by the instrument or partially by the user. The main advantages of self-calibration are faster processing time and better accuracy.
The use of zero-impedance as the reference value is common in a number of applications. However, in many cases, zero-impedance calibration cannot fully satisfy the measurement accuracy. In order to compensate for this, additional calibration procedures are required.
A number of techniques have been developed to improve the accuracy of impedance measurement. Some of these techniques are oscillators, digital AC bridges and frequency domain techniques.
The main goal of an impedance application is to achieve the highest accuracy and repeatability. Modern signal processing techniques such as error correction and Discrete Fourier Transform are used to improve the accuracy of impedance measurement.
