Vector measurement, that is, the determination of the magnitude and phase of a complex quantity, is usually associated with rather sophisticated measurement equipment. The paper shows that a straightforward and cost-effective implementation can be based on a two-channel digital oscilloscope, which acquires data for a simple signal processing algorithm. An analysis of measurement uncertainty indicates that the main limit of the approach is given by the signal-tonoise ratio in the two measurement channels. Experimental results from an application in the telecommunications field are presented.
This paper focuses on the modeling of ferrite transformers for directional couplers up to 1 GHz. Four port scattering parameters of ferrite transformer were measured. On the basis of measured data, transformer model was built for the lower UHF range. Those passive devices are suitable for a class of small signal amplifiers using a transformer and coupler lossless feedback. Using transformer indefinite S matrix overall dissipation loss was analyzed.
The measurement system destined for "blind" dynamic error correction has been presented in the paper. The system consists of double analog channel which measure the same input signal. The structure of the measurement system and the DSP algorithm guarantees in theory that there will be no dynamic error. The single fiber-optic cable has been used for data transmission to a distant DSP equipment. The fiber-optic guarantees very good insulation. The structures of transmitter and receiver have been described. A few methods of data modulation have been discussed with respect to the data rate of...
Conductance cells designed and used according to the van der Pauw method are suitable for the absolute determination of the electrolytic conductivity of solutions and they are more advantageous for this purpose than other calculable cells. Three designs of such cells have been constructed and tested by the author. Results of experimental investigations confirm theoretical expectations and indicate that such a cell can be employed to substitute for standards of electrolytic conductivity. An absolute determination of electrolytic conductivity of 0.01 and 0.1 kmol/m³ NaCl solutions, with an...
In the paper, a voltage comparison circuit and a bridge circuit for impedance measurement by phase shift conversion (IMPSC) is presented. Use of microprocessor has enabled this kind of measurement, as well as error correction of impedance measurement. Error correction is possible thanks to by use of the adaptation procedures, calibration, zeroing, and minimization of influence of the phase shift converter input impedance. Using such impedance measurement a method, as well as mentioned error correction procedures make it possible to measure an impedance of any character, and with values...
The paper presents two thick film inductive sensors having different configuration: the first is a planar spiral while the second one consists of multi-layer spirals. The paper describes how the two sensors have been made, the materials used and their geometric configurations in order to optimize their metrological performances. The spatial distribution of the magnetic field generated by the two sensors has been simulated, while their impedance, the series-equivalent circuit parameters, as well as their sensitivity to temperature variation have been measured in the laboratory. Moreover the...
Use and application of the GTEM-cell, which is a transmission structure based on a TEM-cell approach, has been described. The cell can be used for calibrating small antennas, for immunity and emission testing. Its broadband frequency response from DC up to app. 20 GHz enables laboratory experiments as well as commercial testing of the equipment such as cellular phone, IC boards, or small electronic devices up to 0.2 m × 0.2 m in size. It provides homogenous electromagnetic fields with TEM (transversal electromagnetic mode) distribution, similar to the free space. It has a shield to prevent...
The main task of national laboratory for electrical measurements in Croatia (ETF-PEL) is to ensure a system of international traceability for the basic electromagnetic standards. Traceability of primary resistance standards in Croatia is achieved through comparisons with PTB primary resistance standards using our 1 Ω and 10 kΩ standards. We established traceability chain for the rest of our standards in our laboratory. The methods for comparing standards, and a method of calibrating DMMs have been already published. Determination of DMM error has to be done for any combination of voltages...
An automated microwave phase noise measuring system with improved sensitivity is presented. The system is based on two oscillators measuring method. Improvement of sensitivity can be achieved by increasing the power applied to the RF input of the balanced mixer. However, in classical arrangement of the two oscillators method this is not possible due to already high power contained in the signal carrier. In the proposed measuring system, carrier is suppressed by the resonator. In that way, it is possible to significantly increase RF power from oscillator under test. The sensitivity...