Jiri Svacina

Virtual Anechoic Room An Useful Tool for EMI Pre-Compliance Testing

The paper deals with principles of so-called virtual anechoic room, which presents an economical and accessible possibility of ambient signal elimination in open field test site (OFTS) EMI measurement. Some variants of easy and efficient EM ambient cancellation are described and some measurement examples are presented in the article. In general, the radiated and conducted EM measurement based on principle of virtual anechoic room performs sufficiently accurate results without the need of dedicated and cost expensive OFTS or anechoic chamber.

Variable Impedance in Measuring EMI Filter’s Insertion Loss

This paper deals with problems concerning variable impedance of power lines in the measurement of insertion loss of EMI filters. A circuit which represents variable power line impedance was designed and was added into the normal measuring structure of EMI filters. This was applied to an asymmetrical and a non-symmetrical measurement technique. The design, structure of measurement and results obtained are explained in this paper

Automation Measurement Setups for EMC Laboratory Course

This paper describes a new form of the laboratory exercise in electromagnetic compatibility course at the Department of Radio Electronics in the bachelor study program. Four exercises were modified by using the Agilent VEE Pro graphical language software. Students measure the tasks in laboratory exercises using the personal computer with appropriate program which commands the measuring instruments. Students have to build their oven small and simple programs for commanding the measuring instruments. Students widen their knowledge about automation of measurements in EMC laboratory by exercises modification and also compare the efficiency of the automation measuring system with manual measurements.

Operation Amplifiers in EMI Filter Insertion Loss Measurement Setup

The paper deals with the measuring of the EMI filters insertion loss. Two variations of differential mode measurement setups are compared. Impedance transformers are used in the first setup. Active devices (operational amplifiers) were used in alternative measurement setup instead of impedance transformers. This replacement was done for the 50 Omega differential mode insertion loss measurement setup. The performance of modified measurement setup was tested on several single phase EMI filters. The obtained data were compared with data taken in the setup with impedance transformers.

Bandwidth comparison of various types coplanar microwave ring hybrids

The paper deals with some parameters of microwave ring hybrids mainly from their attainable frequency bandwidth. Selected parameters are especially coupling (C), insertion loss (IL), isolation (I), input VSWR and corresponding bandwidth. We investigated various planar ring hybrids realized in microstrip, coplanar waveguide (CPW), conductor-backed coplanar waveguide (CB-CPW), and CPW-slotline technology, respectively. All couplers are designed for center frequency of 3 GHz and 3 dB coupling. Various hybrids were simulated and compared with measured experimental results.

Dealing with ambient disturbing signals at pre-compliance test sites

Pre-compliance testing is a way how to save money and time during development of electronics.

EM Disturbance Source Position Effect on Measured Field Strength

Radiated disturbance source position effect on measured field strength is described in this paper. Disturbance source position was changed in small area (10 cm) and measured values variation was observed. As a disturbance source was reference source (ERS).