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Right equipment is a Vector Network Analyzer (VNA). The impedance of an antenna in free space, with no objects around to alter its radiation pattern.įortunately, impedance measurements are pretty easy if you have the right equipment. Impedance is sometimes used to mean the input impedance measured in a particular environment, and self-impedance or stand-alone impedance is In an environment that will most closely resemble where it is intended to operate. Consequently, for the best accuracy the impedance should be measured

(as in an airplane antenna), or it may be designed to be integrated within many other metallic components (as in a mobile phoneĪntenna). For example, an antenna could be designed to sit on top of a metal surface

(or an impedance matching network), our antenna will not work properly.īefore we begin, I'd like to point out that objects placed around the antenna can alter its radiation

Will be received by the antenna (if used in the receive mode). Will be transmitted by the antenna (if the antenna is used in the transmit mode), or very little power If the impedance of an antenna is not "close" to that of the transmission line (most often 50 Ohms), then very little power In this section, we'll be concerned with measuring theĪs stated previously, the impedance is a fundamental parameter for antennas. Antenna Impedance Measurements Impedance Measurements Antennas (Home) The Smith chart can be used to simultaneously display multiple parameters including impedances, admittances, reflection coefficients, S n n. It was independently devised by Tōsaku Mizuhashi ( 水橋東作) in 1937, and by Amiel R. The Smith chart (sometimes also called Smith diagram, Mizuhashi chart ( 水橋チャート), Mizuhashi–Smith chart ( 水橋スミスチャート), Volpert–Smith chart ( Диаграмма Вольперта-Смита) and Mizuhashi–Volpert–Smith chart), is a graphical calculator or nomogram designed for electrical and electronics engineers specializing in radio frequency (RF) engineering to assist in solving problems with transmission lines and matching circuits. For other uses of the term Smith diagram, see Smith diagram (disambiguation).