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.

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 uncertainty lower than 0.1%, has been obtained by the author using the cell of a new design.

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 varying within a broad range, without changing the structure of the measuring circuit. This allows co-operation between such circuit and different kinds of impedance sensors constituting the equipment of intelligent measurement nodes in distributed measurement systems.

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 radiation from the outside, which would interfere with our measurement. Electric and magnetic field inside the cell can be accurately predicted using numerical methods. GTEM-cell designed and made at the University of Zagreb, Croatia was presented in this paper as well as the measurements in frequency domain; return loss and standing voltage ratio. Measurement setup and the method have been explained.

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 improvement ranges from 20 to 40 dB.