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A difference in OPL between two paths is often called the optical path difference (OPD). OPL and OPD are important because they determine the phase of the light and govern interference and diffraction of light as it propagates. In a medium of constant refractive index, n, the OPL for a path of geometrical length s is just
The Smith chart graphical equivalent of using the transmission-line equation is to normalise , to plot the resulting point on a Z Smith chart and to draw a circle through that point centred at the Smith chart centre. The path along the arc of the circle represents how the impedance changes whilst moving along the transmission line.
Among the most commonly used methods in the design of radio equipment such as antennas and feeds is the finite-difference time-domain method. The path loss in other frequency bands (medium wave (MW), shortwave (SW or HF), microwave (SHF)) is predicted with similar methods, though the concrete algorithms and formulas may be very different from ...
The Hata model is a radio propagation model for predicting the path loss of cellular transmissions in exterior environments, valid for microwave frequencies from 150 to 1500 MHz. It is an empirical formulation based on the data from the Okumura model , and is thus also commonly referred to as the Okumura–Hata model . [ 1 ]
The free-space path loss (FSPL) formula derives from the Friis transmission formula. [3] This states that in a radio system consisting of a transmitting antenna transmitting radio waves to a receiving antenna, the ratio of radio wave power received P r {\displaystyle P_{r}} to the power transmitted P t {\displaystyle P_{t}} is:
The log-distance path loss model is a radio propagation model that predicts the path loss a signal encounters inside a building or densely populated areas over long distance. While the log-distance model is suitable for longer distances, the short-distance path loss model is often used for indoor environments or very short outdoor distances.
Optical path length (OPL) is the product of the geometric length d of the path light follows through a system, and the index of refraction of the medium through which it propagates, [40] =. This is an important concept in optics because it determines the phase of the light and governs interference and diffraction of light as it propagates.
As polarised light passes through a birefringent sample, the phase difference between the fast and slow directions varies with the thickness, and wavelength of light used. The optical path difference (o.p.d.) is defined as ... =, where t is the thickness of the sample.