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About 1/8 wavelength long: (left) 200 MHz stub is 19 cm, (right) 300 MHz stub is 12.5 cm 10 kW FM broadcast transmitter from 1947 showing quarter-wave resonant stub plate tank circuit. In microwave and radio-frequency engineering, a stub or resonant stub is a length of transmission line or waveguide that is connected at one end only. The free ...
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), [1] [2] [3] Volpert–Smith chart (Диаграмма Вольперта—Смита) [4] [5] or Mizuhashi–Volpert–Smith chart), is a graphical calculator or nomogram designed for electrical and electronics engineers specializing in radio ...
L networks for narrowband matching a source or load impedance Z to a transmission line with characteristic impedance Z 0. X and B may each be either positive (inductor) or negative (capacitor). If Z/Z 0 is inside the 1+jx circle on the Smith chart (i.e. if Re(Z/Z 0)>1), network (a) can be used; otherwise network (b) can be used. [2]
The quarter wave transformer is an alternative to a stub; but, whereas a stub is terminated in a short (or open) circuit and the length is chosen so as to produce the required impedance transformation, the λ/4 transformer is in series with the load and its length and characteristic impedance are designed to produce the required impedance ...
The J-pole antenna is an end-fed omnidirectional half-wave antenna that is matched to the feedline by a shorted quarter-wave parallel transmission line stub. [5] [1] [6] For a transmitting antenna to operate efficiently, absorbing all the power provided by its feedline, the antenna must be impedance matched to the line; it must have a resistance equal to the feedline's characteristic impedance.
Phillip Hagar Smith (April 29, 1905 – August 29, 1987) was an American electrical engineer, who became famous for his invention of the Smith chart.. Smith was born in Lexington, Massachusetts in 1905, and graduated from Tufts College in 1928 with a BS degree in electrical engineering.
Electrical length is widely used with a graphical aid called the Smith chart to solve transmission line calculations. A Smith chart has a scale around the circumference of the circular chart graduated in wavelengths and degrees, which represents the electrical length of the transmission line from the point of measurement to the source or load.
Looking towards a load through a length of lossless transmission line, the impedance changes as increases, following the blue circle on this impedance Smith chart. (This impedance is characterized by its reflection coefficient, which is the reflected voltage divided by the incident voltage.)