negyedhullámú

Negyedhullámú is a Hungarian term that translates to "quarter-wavelength" in English. It commonly refers to a component or a system designed to operate with a specific electrical length equivalent to one-quarter of the wavelength of the signal it is intended for. This concept is fundamental in radio frequency and microwave engineering, particularly in the design of filters, impedance matching networks, and antennas.

A quarter-wavelength transmission line, when terminated in a specific impedance, exhibits unique properties. For instance, if a quarter-wavelength transmission line is short-circuited at one end, its input impedance appears as an open circuit. Conversely, if it is open-circuited at one end, its input impedance appears as a short circuit. This characteristic makes it useful for creating resonant structures or for transforming impedances.

In practical applications, quarter-wavelength sections are often implemented using microstrip lines on printed circuit boards or as sections of coaxial cable. The exact physical length of a quarter-wavelength element depends on the dielectric material used and the frequency of operation, often requiring a calculation using the formula for wavelength adjusted by the velocity factor of the transmission medium. This principle is applied in various electronic devices, from simple radio receivers to complex radar systems.