Stanislava Papezova

3D printing is more and more often used for the development and manufacturing of electronic devices and components. These applications require knowledge about the dielectric properties of the used materials—in particular minimal and stable values of relative permittivity and dielectric losses. The paper deals with the testing of the relative permittivity and loss factor of materials as follows: PLA (in three dye modifications), PET-G, and ABS and ASA in the frequency range 1–100 MHz. It was found that relative permittivity varied between 2.88–3.48 and the loss factor was in the range 0.03–4.31%. In terms of relative permittivity, all tested materials manifested a slight decline with increasing frequency. Concerning loss factor PLA (colorless) and ABS were proven to be more suitable for electrotechnical application due to the lower values and frequency dependences of the loss factor. Different results were observed in PLA-Silver and PLA-Metallic green. These materials showed a higher frequency dependency of loss factor with increasing frequency. The reasonable influence of added dyes was found. A study of the internal structure of the tested materials has not proven any significant defects (air gaps) that could affect the material’s dielectric properties.

Traditional methods and new method for measurement of low non-linearity of electronic components and circuits are described in this paper. Maintaining a linearity of components and circuits that are on principle linear is a measure of their quality. Passive intermodulation distortion (PIM) and non-linearity itself arises as a result of faults in production or component degradation and limits their usability.

This article describes a device for a phase noise measurement using the phase locked loop (PLL). This allows measuring signals with the possibility of passing the phase noise better than -160 dB. There are analyzed the effects of the measuring device on the measuring results and presented examples of solving the PLL, circuits for low-frequency signal processing and power supplies with their minimal basic noise.

The paper describes a special method for testing power capacitors by means of their loading by alternating current with the effective value up to 100 A at frequencies in the order of units up to tens of kHz. There is described the realization of the test equipment enabling a precise compensation of the reactive power of the capacitor and the input minimisation at the testing. It discusses the realization of the key components and parts of the measuring equipment.

This article describes a device for phase noise measurement using the phase lock technique. This allows the user to measure signals with level of the phase noise lower than -160 dBc/Hz. The effects of the measuring device on the measurement results are analyzed and examples phase noise measurements using PLL method, circuits for low-frequency signal processing and for power supplies with minimal own noise are presented.

This paper describes a circuit arrangement, design and construction of the power load composed of many pieces of thick film flanged resistors, which are serial-parallel connected so that the resulting combination showed the desired impedance-resistance, which may or may not be consistent with the resistance of individual components and, at the same time, it can be loaded with more power than a single component. The solution is given to the compensation circuit which increases several times the maximum frequency at which the load is applied.

Bio-impedance evaluation is one of the medicine diagnostic methods for the evaluation of tissue perfusion. The bioimpedance on the patient's body surface is evaluated by analogue HF-vector Z-meter. The Z signal is converted into a digital form and further digitally processed and filtered. Spurious disturbing signals distorting the bio-impedance signal are suppressed by adaptive FIR filter.

This contribution describes bridge symmetric crystal oscillator. A selective component of the oscillator is realized as Wheatstone bridge with two identical crystal resonators. An amplifier of this oscillator is realized as a symmetrical differential amplifier. Oscillator is especially solved with a view to achieve minimal phase noise of generated signal. Results are compared with common Gouriet-Clapp oscillator.

This paper describes a wire resistor with the resistance of several hundreds ohms, with a power dissipation up to several hundreds watts. In a high frequency band, it shows maximum frequency reflection coefficient values with respect to the nominal resistance value of about 0.1, and which reaches a third order IM distortion products close to -130dBc at the dissipation power.