Naslov
RF Transmission Line Structures with Uniform Field Distribution

Autori
Malarić, Krešimir

Vrsta, podvrsta i kategorija knjige
Autorske knjige, monografija, znanstvena

Izdavač
Lambert Academic Publishing

Grad
Saarbrücken

Godina
2011

Stranica
144

ISBN
978-3-8454-3217-5

Ključne riječi
TEM; GTEM cell; transmission structures; numerical methods

Sažetak
With the increase in the frequency range, and reducing the size of the structures due to the appearance of the higher modes, a situation appeared where nothing larger than a probe could be inserted inside the structure. Variations of the cells, together with the introduction of the absorbers took place. In this work, transmission lines in the higher radio frequency range were analyzed. Survey of basic transmission structures, both homogenous and non-homogenous was given. Numerical methods and basic types of TEM cells have been analyzed. TEM cell and GTEM cell were made at the Department for the Radiocommunications and Microwave Engineering, they have been numerically analyzed and their parameters measured. Theoretical analysis of EM field distribution, excitation and higher modes has been done. Measurements have been compared to the calculation. Two computer programs for the calculation of the higher modes for TEM and GTEM cell have been programmed. The electric field was measured with the probe. In the end, there is a survey of standards and standard associations. TEM cell was made with the characteristic impedance of 75 ohms, which enabled larger test area (up to 5 cm in height, which is 2, 5x more than with commercially available cells in this frequency range), with the areas where TEM mode can propagate even above the first resonant frequency. Such area is around 900 MHz, which means that TEM cell can be used for GSM measurements. Biological effects can be tested as well. TEM cell is usable for testing susceptibility and emission. Performed measurements and numerical analysis confirmed the calculations. GTEM cell, also made at the Department for the Radiocommunications and Microwave Engineering, can be used for testing from DC to 18 GHz. The size of the test object is 20 cm x 20 cm. GTEM cell has distributed load ; resistors for low frequency termination and pyramidal absorbers for the electromagnetic wave. Measurements and numerical analysis confirmed the results. This cell also can be used for the same purpose as TEM cell, with the difference that it covers a much larger frequency range. Both TEM and GTEM cells were modeled, regarding electric and magnetic field distribution as well as higher mode resonance. Extensive measurements were performed on the GTEM cell, particularly the influence of the absorber and resistors. Open GTEM cell, and GTEM cell without absorbers and resistors have been measured. Current distributions on the septum have been also performed. TEM cell made at the Department for the Radiocommunications and Microwave Engineering enables the use of frequency range up to 1 GHz (with coaxial connectors) for measuring emission and susceptibility, as well as for biomedical experiments. It is simple to build, so it can be available to every laboratory or research center. GTEM cell is somewhat more complex, but it has better characteristics, that is, it covers a larger frequency range. The laboratories in the world have various types of cells, such as TEM and GTEM cells, semi-anechois and full-anechoic chambers, which can be used for Electromagnetic compatibility testing.

Izvorni jezik
Engleski

Znanstvena područja
Elektrotehnika

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