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Voltage standing wave ratio (VSWR) (pronounced "vizwar" [1] [2]) is the ratio of maximum to minimum voltage on a transmission line . For example, a VSWR of 1.2 means a peak voltage 1.2 times the minimum voltage along that line, if the line is at least one half wavelength long.
A time-domain reflectometer; an instrument used to locate the position of faults on lines from the time taken for a reflected wave to return from the discontinuity.. A signal travelling along an electrical transmission line will be partly, or wholly, reflected back in the opposite direction when the travelling signal encounters a discontinuity in the characteristic impedance of the line, or if ...
Impedance discontinuities cause attenuation, attenuation distortion, standing waves, ringing and other effects because a portion of a transmitted signal will be reflected back to the transmitting device rather than continuing to the receiver, much like an echo. This effect is compounded if multiple discontinuities cause additional portions of ...
[1]: 27‑21 The meter or amplifier (not shown) connected to the FWD and REV terminals acts as the required drain resistor, and determines the dwell-time of the meter reading. Interior view of an SWR meter. The three parallel coupled lines are visible. Diodes, capacitors and termination resistors are mounted at the ends of the sense lines.
Any component of the transmission line that has an input and output will contribute to the overall mismatch loss of the system. For example, in mixers mismatch loss occurs when there is an impedance mismatch between the RF port and IF port of the mixer [dubious – discuss]. [4]
When input and output impedances are the same, voltage attenuation will be the square root of power attenuation, so, for example, a 6 dB attenuator that reduces power to one fourth will reduce the voltage (and the current) by half. Nominal impedance, for example 50 ohm; Frequency bandwidth, for example DC-18 GHz
In telecommunications, the free-space path loss (FSPL) (also known as free-space loss, FSL) is the attenuation of radio energy between the feedpoints of two antennas that results from the combination of the receiving antenna's capture area plus the obstacle-free, line-of-sight (LoS) path through free space (usually air). [1]
ZVA40 vector network analyzer from Rohde & Schwarz.. A network analyzer is an instrument that measures the network parameters of electrical networks.Today, network analyzers commonly measure s–parameters because reflection and transmission of electrical networks are easy to measure at high frequencies, but there are other network parameter sets such as y-parameters, z-parameters, and h ...