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<p><b>Path loss</b>, or <b>path attenuation</b>, is the reduction in power density (<a href="Attenuation_(electromagnetic_radiation)" class="mw-redirect" title="Attenuation (electromagnetic radiation)">attenuation</a>) of an <a href="Electromagnetic_wave" class="mw-redirect" title="Electromagnetic wave">electromagnetic wave</a> as it propagates through space.<sup id="cite_ref-1" class="reference"><a href="#cite_note-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> Path loss is a major component in the analysis and design of the <a href="Link_budget" title="Link budget">link budget</a> of a telecommunication system.

</p><p>This term is commonly used in <a href="Wireless_communications" class="mw-redirect" title="Wireless communications">wireless communications</a> and <a href="Signal_propagation" class="mw-redirect" title="Signal propagation">signal propagation</a>. Path loss may be due to many effects, such as <a href="Free-space_loss" class="mw-redirect" title="Free-space loss">free-space loss</a>, <a href="Refraction" title="Refraction">refraction</a>, <a href="Diffraction" title="Diffraction">diffraction</a>, <a href="Reflection_(physics)" title="Reflection (physics)">reflection</a>, <a href="Aperture_(antenna)" title="Aperture (antenna)">aperture</a>-<a href="Transmission_medium" title="Transmission medium">medium</a> <a href="Coupling_loss" title="Coupling loss">coupling loss</a>, and <a href="Absorption_(electromagnetic_radiation)" title="Absorption (electromagnetic radiation)">absorption</a>. Path loss is also influenced by terrain contours, environment (urban or rural, vegetation and foliage), propagation medium (dry or moist air), the distance between the transmitter and the receiver, and the height and location of antennas.

</p>

<div class="mw-heading mw-heading2"><h2 id="Overview">Overview</h2></div>

<p>In wireless communications, path loss is the reduction in signal strength as the signal travels from a transmitter to a receiver, and is an application for verifying the loss. There are several factors that affect this:

</p>

<ul><li>Free-space path loss: This is the fundamental loss that occurs due to the spreading of the radio wave as it propagates through space. <sup id="cite_ref-2" class="reference"><a href="#cite_note-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> It follows an inverse square law, meaning the signal strength decreases proportionally to the square of the distance between the transmitter and receiver.</li></ul>

<ul><li>Diffraction: When a radio wave encounters an obstacle, it can be diffracted, or bent around the edge of the obstacle. This can cause additional signal loss, especially in urban environments with many buildings. <sup id="cite_ref-3" class="reference"><a href="#cite_note-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup></li></ul>

<ul><li>Absorption: Certain atmospheric gases and obstacles like buildings and foliage can absorb radio waves, reducing their strength.<sup id="cite_ref-4" class="reference"><a href="#cite_note-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup></li></ul>

<ul><li>Reflection and scattering: Radio waves can be reflected off surfaces like buildings and the ground, and scattered by objects like trees and lampposts. This can lead to multipath propagation, where the receiver receives multiple copies of the signal that may interfere with each other. <sup id="cite_ref-5" class="reference"><a href="#cite_note-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup></li></ul>

<p>In understanding path loss and minimizing it, there are four key factors to consider in designing a wireless communication system:

</p><p>1) Determining the required transmitter power: The transmitter must have enough power to overcome the path loss in order for the signal to reach the receiver with sufficient strength.

</p><p>2) Determine the appropriate antenna design and gain: Antennas with higher gain can focus the waves in a specific direction, reducing the path loss.

</p><p>3) Optimize modulation scheme: The choice of modulation scheme can affect the robustness of the signal to path loss.

</p><p>4) Set the receiver sensitivity appropriately: The receiver must be sensitive enough to detect weak signals.

</p>

<div class="mw-heading mw-heading2"><h2 id="Causes">Causes</h2></div>

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<p>Path loss normally includes <i>propagation losses</i> caused by the natural expansion of the <a href="Radio_wave" title="Radio wave">radio wave</a> front in <a href="Free_space" class="mw-redirect" title="Free space">free space</a> (which usually takes the shape of an ever-increasing sphere), <i>absorption losses</i> (sometimes called penetration losses), when the signal passes through media not transparent to <a href="Electromagnetic_waves" class="mw-redirect" title="Electromagnetic waves">electromagnetic waves</a>, <i><a href="Diffraction" title="Diffraction">diffraction</a> losses</i> when part of the radiowave front is obstructed by an opaque obstacle, and losses caused by other phenomena.

</p><p>The signal radiated by a transmitter may also travel along many and different paths to a receiver simultaneously; this effect is called <a href="Multipath_propagation" title="Multipath propagation">multipath</a>. Multipath waves combine at the receiver antenna, resulting in a received signal that may vary widely, depending on the distribution of the intensity and relative propagation time of the waves and bandwidth of the transmitted signal. The total power of interfering waves in a <a href="Rayleigh_fading" title="Rayleigh fading">Rayleigh fading</a> scenario varies quickly as a function of space (which is known as <i>small scale <a href="Fading" title="Fading">fading</a></i>). Small-scale fading refers to the rapid changes in radio signal amplitude in a short period of time or distance of travel.

</p>

<div class="mw-heading mw-heading2"><h2 id="Loss_exponent">Loss exponent</h2></div>

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</style><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="Log-distance_path_loss_model" title="Log-distance path loss model">Log-distance path loss model</a></div>

<p>In the study of wireless communications, path loss can be represented by the path loss exponent, whose value is normally in the range of 2 to 4 (where 2 is for propagation in <a href="Free_space" class="mw-redirect" title="Free space">free space</a>, 4 is for relatively lossy environments and for the case of full <a href="Specular_reflection" title="Specular reflection">specular reflection</a> from the earth surface—the so-called flat earth model). In some environments, such as buildings, stadiums and other indoor environments, the path loss exponent can reach values in the range of 4 to 6. On the other hand, a tunnel may act as a <a href="Waveguide" title="Waveguide">waveguide</a>, resulting in a path loss exponent less than 2.

</p><p>Path loss is usually expressed in <a href="Decibel" title="Decibel">dB</a>. In its simplest form, the path loss can be calculated using the formula

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<msub>

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<annotation encoding="application/x-tex">{\displaystyle L=10n\log _{10}(d)+C}</annotation>

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</math></span><img src="./892b97f66824656b3d80025457f946666a86726b.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:21.268ex; height:2.843ex;" alt="{\displaystyle L=10n\log _{10}(d)+C}" loading="lazy"></span></dd></dl>

<p>where <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle L}">

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle L}</annotation>

</semantics>

</math></span><img src="./103168b86f781fe6e9a4a87b8ea1cebe0ad4ede8.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.583ex; height:2.176ex;" alt="{\displaystyle L}" loading="lazy"></span> is the path loss in decibels, <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle n}">

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle n}</annotation>

</semantics>

</math></span><img src="./a601995d55609f2d9f5e233e36fbe9ea26011b3b.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.395ex; height:1.676ex;" alt="{\displaystyle n}" loading="lazy"></span> is the path loss exponent, <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle d}">

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle d}</annotation>

</semantics>

</math></span><img src="./e85ff03cbe0c7341af6b982e47e9f90d235c66ab.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.216ex; height:2.176ex;" alt="{\displaystyle d}" loading="lazy"></span> is the distance between the transmitter and the receiver, usually measured in meters, and <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle C}">

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<annotation encoding="application/x-tex">{\displaystyle C}</annotation>

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</math></span><img src="./4fc55753007cd3c18576f7933f6f089196732029.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.766ex; height:2.176ex;" alt="{\displaystyle C}" loading="lazy"></span> is a constant which accounts for system losses.

</p>

<div class="mw-heading mw-heading2"><h2 id="Radio_engineer_formula">Radio engineer formula</h2></div>

<p>Radio and antenna engineers use the following simplified formula (derived from the <a href="Friis_transmission_equation" title="Friis transmission equation">Friis Transmission Formula</a>) for the signal path loss between the feed points of two <a href="Isotropic" class="mw-redirect" title="Isotropic">isotropic</a> antennas in free space:

</p><p>Path loss in <a href="Decibel" title="Decibel">dB</a>:

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<annotation encoding="application/x-tex">{\displaystyle L=20\log _{10}\left({\frac {4\pi d}{\lambda }}\right)}</annotation>

</semantics>

</math></span><img src="./d2985af7ed0a49562a7c28bc05559f12a7955c64.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.505ex; width:20.209ex; height:6.176ex;" alt="{\displaystyle L=20\log _{10}\left({\frac {4\pi d}{\lambda }}\right)}" loading="lazy"></span></dd></dl>

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle L}</annotation>

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<annotation encoding="application/x-tex">{\displaystyle \lambda }</annotation>

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</math></span><img src="./b43d0ea3c9c025af1be9128e62a18fa74bedda2a.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.355ex; height:2.176ex;" alt="{\displaystyle \lambda }" loading="lazy"></span> is the wavelength and <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle d}">

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<annotation encoding="application/x-tex">{\displaystyle d}</annotation>

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</math></span><img src="./e85ff03cbe0c7341af6b982e47e9f90d235c66ab.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.216ex; height:2.176ex;" alt="{\displaystyle d}" loading="lazy"></span> is the transmitter-receiver distance in the same units as the wavelength. Note the power density in space has no dependency on <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \lambda }">

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle \lambda }</annotation>

</semantics>

</math></span><img src="./b43d0ea3c9c025af1be9128e62a18fa74bedda2a.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.355ex; height:2.176ex;" alt="{\displaystyle \lambda }" loading="lazy"></span>; The variable <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \lambda }">

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle \lambda }</annotation>

</semantics>

</math></span><img src="./b43d0ea3c9c025af1be9128e62a18fa74bedda2a.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.355ex; height:2.176ex;" alt="{\displaystyle \lambda }" loading="lazy"></span> exists in the formula to account for the <a href="Antenna_aperture" class="mw-redirect" title="Antenna aperture">effective capture area</a> of the isotropic receiving antenna.<sup id="cite_ref-Stutz_6-0" class="reference"><a href="#cite_note-Stutz-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup>

</p>

<div class="mw-heading mw-heading2"><h2 id="Prediction">Prediction</h2></div>

<p>Calculation of the path loss is usually called <i>prediction</i>. Exact prediction is possible only for simpler cases, such as the above-mentioned <i>free space</i> propagation or the <i>flat-earth model</i>. For practical cases the path loss is calculated using a variety of approximations.

</p><p><i>Statistical</i> methods (also called <i>stochastic</i> or <i>empirical</i>) are based on measured and averaged losses along typical classes of radio links. Among the most commonly used such methods are <a href="Hata_Model_for_Urban_Areas" class="mw-redirect" title="Hata Model for Urban Areas">Okumura–Hata</a>, the <a href="COST_Hata_model" title="COST Hata model">COST Hata model</a>, W.C.Y.Lee, etc. These are also known as <i>radio wave propagation models</i> and are typically used in the design of <a href="Cellular_networks" class="mw-redirect" title="Cellular networks">cellular networks</a> and <a href="Public_land_mobile_network" title="Public land mobile network">public land mobile networks</a> (PLMN). For wireless communications in the <a href="Very_high_frequency" title="Very high frequency">very high frequency</a> (VHF) and <a href="Ultra_high_frequency" title="Ultra high frequency">ultra high frequency</a> (UHF) frequency band (the bands used by walkie-talkies, police, taxis and cellular phones), one of the most commonly used methods is that of Okumura–Hata as refined by the <a href="Cost_231_Model" class="mw-redirect" title="Cost 231 Model">COST 231</a> project. Other well-known models are those of Walfisch–Ikegami, W. C. Y. Lee, and <a href="Erceg" title="Erceg">Erceg</a>. For FM radio and TV broadcasting the path loss is most commonly predicted using the <a href="ITU" class="mw-redirect" title="ITU">ITU</a> model as described in P.1546 (successor to P.370) recommendation.

</p><p>Deterministic methods based on the physical laws of wave propagation are also used; <a href="Ray_tracing_(physics)" title="Ray tracing (physics)">ray tracing</a> is one such method. These methods are expected to produce more accurate and reliable predictions of the path loss than the empirical methods; however, they are significantly more expensive in computational effort and depend on the detailed and accurate description of all objects in the propagation space, such as buildings, roofs, windows, doors, and walls. For these reasons they are used predominantly for short propagation paths. Among the most commonly used methods in the design of radio equipment such as antennas and feeds is the <a href="Finite-difference_time-domain_method" title="Finite-difference time-domain method">finite-difference time-domain method</a>.

</p><p>The path loss in other frequency bands (<a href="Medium_wave" title="Medium wave">medium wave</a> (MW), <a href="Shortwave" class="mw-redirect" title="Shortwave">shortwave</a> (SW or HF), <a href="Microwave" title="Microwave">microwave</a> (SHF)) is predicted with similar methods, though the concrete algorithms and formulas may be very different from those for VHF/UHF. Reliable prediction of the path loss in the SW/HF band is particularly difficult, and its accuracy is comparable to weather predictions.

</p><p>Easy approximations for calculating the path loss over distances significantly shorter than the distance to the <a href="Radio_horizon" class="mw-redirect" title="Radio horizon">radio horizon</a>:

</p>

<ul><li>In free space the path loss increases with 20 dB per <i>decade</i> (one decade is when the distance between the transmitter and the receiver increases ten times) or 6 dB per <i>octave</i> (one octave is when the distance between the transmitter and the receiver doubles). This can be used as a very rough first-order approximation for (microwave) communication links;</li>

<li>For signals in the UHF/VHF band propagating over the surface of the Earth the path loss increases with roughly 35–40 dB per decade (10–12 dB per octave). This can be used in cellular networks as a first guess.</li></ul>

<div class="mw-heading mw-heading2"><h2 id="Examples">Examples</h2></div>

<p>In cellular networks, such as <a href="UMTS" title="UMTS">UMTS</a> and <a href="GSM" title="GSM">GSM</a>, which operate in the UHF band, the value of the path loss in built-up areas can reach 110–140 dB for the first kilometer of the link between the <a href="Base_transceiver_station" title="Base transceiver station">base transceiver station</a> (BTS) and the <a href="Mobile_phone" title="Mobile phone">mobile</a>. The path loss for the first ten kilometers may be 150–190 dB (<i>Note</i>: These values are very approximate and are given here only as an illustration of the range in which the numbers used to express the path loss values <i>can eventually be</i>, these are not definitive or binding figures—the path loss may be very different for the same distance along two different paths and it can be different even along the same path if measured at different times.)

</p><p>In the radio wave environment for mobile services the mobile antenna is close to the ground. <a href="Line-of-sight_propagation" title="Line-of-sight propagation">Line-of-sight propagation</a> (LOS) models are highly modified. The signal path from the BTS antenna normally elevated above the roof tops is refracted down into the local physical environment (hills, trees, houses) and the LOS signal seldom reaches the antenna. The environment will produce several deflections of the direct signal onto the antenna, where typically 2–5 deflected signal components will be vectorially added.

</p><p>These refraction and deflection processes cause loss of signal strength, which changes when the mobile antenna moves (Rayleigh fading), causing instantaneous variations of up to 20 dB. The network is therefore designed to provide an excess of signal strength compared to LOS of 8–25 dB depending on the nature of the physical environment, and another 10 dB to overcome the fading due to movement.

</p>

<ul><li><a href="Air_mass_(astronomy)" title="Air mass (astronomy)">Air mass (astronomy)</a></li>

<li><a href="Radio_propagation_model" class="mw-redirect" title="Radio propagation model">Radio propagation model</a></li>

<li><a href="Log-distance_path_loss_model" title="Log-distance path loss model">Log-distance path loss model</a></li>

<li><a href="Two-ray_ground-reflection_model" title="Two-ray ground-reflection model">Two-ray ground-reflection model</a></li>

<li><a href="Computation_of_radiowave_attenuation_in_the_atmosphere" class="mw-redirect" title="Computation of radiowave attenuation in the atmosphere">Computation of radiowave attenuation in the atmosphere</a></li></ul>

<div class="mw-heading mw-heading2"><h2 id="References">References</h2></div>

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</style><cite id="CITEREFSariAlzubi2018" class="citation cs2">Sari, Arif; Alzubi, Ahmed (2018-01-01), Ficco, Massimo; Palmieri, Francesco (eds.), <a rel="nofollow" class="external text" href="https://www.sciencedirect.com/science/article/pii/B9780128113738000136">"Chapter 13 - Path Loss Algorithms for Data Resilience in Wireless Body Area Networks for Healthcare Framework"</a>, <i>Security and Resilience in Intelligent Data-Centric Systems and Communication Networks</i>, Intelligent Data-Centric Systems, Academic Press, p. 303, <a href="ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <bdi>978-0-12-811373-8</bdi><span class="reference-accessdate">, retrieved <span class="nowrap">2023-06-03</span></span></cite></span>

</li>

<li id="cite_note-2"><span class="mw-cite-backlink"><b><a href="#cite_ref-2">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external free" href="https://semfionetworks.com/blog/free-space-path-loss-diagrams/">https://semfionetworks.com/blog/free-space-path-loss-diagrams/</a></span>

</li>

<li id="cite_note-3"><span class="mw-cite-backlink"><b><a href="#cite_ref-3">^</a></b></span> <span class="reference-text"> <a rel="nofollow" class="external free" href="https://www.researchgate.net/figure/llustration-of-reflection-diffraction-scattering-and-absorption_fig2_228041875">https://www.researchgate.net/figure/llustration-of-reflection-diffraction-scattering-and-absorption_fig2_228041875</a></span>

</li>

<li id="cite_note-4"><span class="mw-cite-backlink"><b><a href="#cite_ref-4">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external free" href="https://www.twc-net.com/blog/uncategorized/a46">https://www.twc-net.com/blog/uncategorized/a46</a></span>

</li>

<li id="cite_note-5"><span class="mw-cite-backlink"><b><a href="#cite_ref-5">^</a></b></span> <span class="reference-text"> <a rel="nofollow" class="external free" href="https://www.researchgate.net/figure/Reflection-scattering-and-diffraction-of-signal-Tait-Communications-2015_fig1_326705984">https://www.researchgate.net/figure/Reflection-scattering-and-diffraction-of-signal-Tait-Communications-2015_fig1_326705984</a></span>

</li>

<li id="cite_note-Stutz-6"><span class="mw-cite-backlink"><b><a href="#cite_ref-Stutz_6-0">^</a></b></span> <span class="reference-text"><cite id="CITEREFStutzmanThiele1981" class="citation book cs1">Stutzman, Warren; Thiele, Gary (1981). <i>Antenna Theory and Design</i>. John Wiley & Sons, Inc. p. 60. <a href="ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <bdi>0-471-04458-X</bdi>.</cite></span>

</li>

</ol></div></div>

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</style><span class="citation FS1037C MS188"><span class="noviewer" typeof="mw:File"><span></span></span> This article incorporates <a href="Copyright_status_of_works_by_the_federal_government_of_the_United_States" title="Copyright status of works by the federal government of the United States">public domain material</a> from <cite class="citation cs1"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20220122224547/https://www.its.bldrdoc.gov/fs-1037/fs-1037c.htm"><i>Federal Standard 1037C</i></a>. <a href="General_Services_Administration" title="General Services Administration">General Services Administration</a>. Archived from <a rel="nofollow" class="external text" href="https://www.its.bldrdoc.gov/fs-1037/fs-1037c.htm">the original</a> on 2022-01-22.</cite> (in support of <a href="MIL-STD-188" title="MIL-STD-188">MIL-STD-188</a>).</span></li></ul>

<div class="mw-heading mw-heading2"><h2 id="External_links">External links</h2></div>

<ul><li><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.europeana.eu/resolve/record/9200111/83299BB8CE5435AA4953615C2812EAC4A83FE90A">"Methods for Path loss Prediction"</a>.</cite></li></ul>

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</style><div id="Analog_television_broadcasting_topics253" style="font-size:114%;margin:0 4em"><a href="Analog_television" title="Analog television">Analog television</a> <a href="Outline_of_television_broadcasting" title="Outline of television broadcasting">broadcasting topics</a></div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Broadcast_television_systems" title="Broadcast television systems">Systems</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<li><a href="405-line_television_system" title="405-line television system">405-line</a> (<a href="CCIR_System_A" title="CCIR System A">System A</a>)</li>

<li><a href="525-line_television_system" class="mw-redirect" title="525-line television system">525-line</a> (<a href="CCIR_System_M" title="CCIR System M">System M</a>)</li>

<li><a href="625-line_television_system" class="mw-redirect" title="625-line television system">625-line</a> (<a href="CCIR_System_B" title="CCIR System B">System B</a>, <a href="CCIR_System_C" title="CCIR System C">System C</a>, <a href="CCIR_System_D" title="CCIR System D">System D</a>, <a href="CCIR_System_G" title="CCIR System G">System G</a>, <a href="CCIR_System_H" title="CCIR System H">System H</a>, <a href="CCIR_System_I" title="CCIR System I">System I</a>, <a href="CCIR_System_K" title="CCIR System K">System K</a>, <a href="CCIR_System_L" title="CCIR System L">System L</a>, <a href="CCIR_System_N" title="CCIR System N">System N</a>)</li>

<li><a href="819_line" title="819 line">819-line</a> (<a href="CCIR_System_E" title="CCIR System E">System E</a>, <a href="CCIR_System_F" title="CCIR System F">System F</a>)</li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Color systems</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<li><a href="Clear-Vision" title="Clear-Vision">Clear-Vision</a></li>

<li><a href="PALplus" title="PALplus">PALplus</a></li>

<li><a href="SECAM" title="SECAM">SECAM</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Video</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Analog_television#Structure_of_a_video_signal" title="Analog television">Back porch</a> and <a href="Analog_television#Structure_of_a_video_signal" title="Analog television">front porch</a></li>

<li><a href="Black_level" title="Black level">Black level</a></li>

<li><a href="Blanking_level" title="Blanking level">Blanking level</a></li>

<li><a href="Chrominance" title="Chrominance">Chrominance</a></li>

<li><a href="Chrominance_subcarrier" title="Chrominance subcarrier">Chrominance subcarrier</a></li>

<li><a href="Colorburst" title="Colorburst">Colorburst</a></li>

<li><a href="Color_killer" title="Color killer">Color killer</a></li>

<li><a href="Color_television" title="Color television">Color TV</a></li>

<li><a href="Composite_video" title="Composite video">Composite video</a></li>

<li><a href="Frame_(video)" class="mw-redirect" title="Frame (video)">Frame (video)</a></li>

<li><a href="Horizontal_scan_rate" title="Horizontal scan rate">Horizontal scan rate</a></li>

<li><a href="Horizontal_blanking_interval" title="Horizontal blanking interval">Horizontal blanking interval</a></li>

<li><a href="Nominal_analogue_blanking" title="Nominal analogue blanking">Nominal analogue blanking</a></li>

<li><a href="Overscan" title="Overscan">Overscan</a></li>

<li><a href="Raster_scan" title="Raster scan">Raster scan</a></li>

<li><a href="Television_lines" title="Television lines">Television lines</a></li>

<li><a href="Vertical_blanking_interval" title="Vertical blanking interval">Vertical blanking interval</a></li>

<li><a href="White_clipper" title="White clipper">White clipper</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Sound</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Multichannel_Television_Sound" title="Multichannel Television Sound">Multichannel Television Sound</a></li>

<li><a href="NICAM" title="NICAM">NICAM</a></li>

<li><a href="Sound-in-Syncs" title="Sound-in-Syncs">Sound-in-Syncs</a></li>

<li><a href="Zweikanalton" title="Zweikanalton">Zweikanalton</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Modulation</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Frequency_modulation" title="Frequency modulation">Frequency modulation</a></li>

<li><a href="Quadrature_amplitude_modulation" title="Quadrature amplitude modulation">Quadrature amplitude modulation</a></li>

<li><a href="Single-sideband_modulation#Vestigial_sideband_(VSB)" title="Single-sideband modulation">Vestigial sideband modulation (VSB)</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Transmission</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Amplifier#Electronic_amplifiers" title="Amplifier">Amplifiers</a></li>

<li><a href="Antenna_(radio)" title="Antenna (radio)">Antenna (radio)</a></li>

<li><a href="Broadcast_transmitter" title="Broadcast transmitter">Broadcast transmitter</a>/<a href="Transmitter_station" title="Transmitter station">Transmitter station</a></li>

<li><a href="Resonator#Electromagnetic" title="Resonator">Cavity amplifier</a></li>

<li><a href="Differential_gain" title="Differential gain">Differential gain</a></li>

<li><a href="Differential_phase" title="Differential phase">Differential phase</a></li>

<li><a href="Diplexer" title="Diplexer">Diplexer</a></li>

<li><a href="Dipole_antenna" title="Dipole antenna">Dipole antenna</a></li>

<li><a href="Dummy_load" title="Dummy load">Dummy load</a></li>

<li><a href="Frequency_mixer" title="Frequency mixer">Frequency mixer</a></li>

<li><a href="Intercarrier_method" title="Intercarrier method">Intercarrier method</a></li>

<li><a href="Intermediate_frequency" title="Intermediate frequency">Intermediate frequency</a></li>

<li><a href="Output_power_of_an_analog_TV_transmitter" title="Output power of an analog TV transmitter">Output power of an analog TV transmitter</a></li>

<li><a href="Pre-emphasis" class="mw-redirect" title="Pre-emphasis">Pre-emphasis</a></li>

<li><a href="Residual_carrier" title="Residual carrier">Residual carrier</a></li>

<li><a href="Split_sound_system" title="Split sound system">Split sound system</a></li>

<li><a href="Superheterodyne_transmitter" title="Superheterodyne transmitter">Superheterodyne transmitter</a></li>

<li><a href="Television_receive-only" title="Television receive-only">Television receive-only</a></li>

<li><a href="Direct-broadcast_satellite_television" class="mw-redirect" title="Direct-broadcast satellite television">Direct-broadcast satellite television</a></li>

<li><a href="Television_transmitter" title="Television transmitter">Television transmitter</a></li>

<li><a href="Terrestrial_television" title="Terrestrial television">Terrestrial television</a></li>

<li><a href="Transposer" title="Transposer">Transposer</a></li>

<li><a href="Digital_television_transition" title="Digital television transition">Digital television transition</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Radio_frequency" title="Radio frequency">Frequencies</a> & bands</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Frequency_offset" title="Frequency offset">Frequency offset</a></li>

<li><a href="Microwave_transmission" title="Microwave transmission">Microwave transmission</a></li>

<li><a href="Television_channel_frequencies" title="Television channel frequencies">Television channel frequencies</a></li>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Radio_propagation" title="Radio propagation">Propagation</a></th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<li><a href="Distortion" title="Distortion">Distortion</a></li>

<li><a href="Earth_bulge" class="mw-redirect" title="Earth bulge">Earth bulge</a></li>

<li><a href="Field_strength_in_free_space" class="mw-redirect" title="Field strength in free space">Field strength in free space</a></li>

<li><a href="Noise_(electronics)" title="Noise (electronics)">Noise (electronics)</a></li>

<li><a href="Radiation_pattern" title="Radiation pattern">Radiation pattern</a></li>

<li><a href="Television_interference" title="Television interference">Television interference</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Testing</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Distortionmeter" title="Distortionmeter">Distortionmeter</a></li>

<li><a href="Field_strength_meter" title="Field strength meter">Field strength meter</a></li>

<li><a href="Vectorscope" title="Vectorscope">Vectorscope</a></li>

<li><a href="VIT_signals" title="VIT signals">VIT signals</a></li>

<li><a href="Zero_reference_pulse" title="Zero reference pulse">Zero reference pulse</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Artifacts</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Dot_crawl" title="Dot crawl">Dot crawl</a></li>

<li><a href="Ghosting_(television)" title="Ghosting (television)">Ghosting</a></li>

<li><a href="Hanover_bars" title="Hanover bars">Hanover bars</a></li>

<li><a href="Sparklies" title="Sparklies">Sparklies</a></li></ul>

</div></td></tr></tbody></table></div>

<div class="navbox-styles"></div><div role="navigation" class="navbox" aria-labelledby="Radio_frequency_propagation_models129" style="padding:3px"><table class="nowraplinks hlist mw-collapsible autocollapse navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><div id="Radio_frequency_propagation_models129" style="font-size:114%;margin:0 4em"><a href="Radio_propagation_model" class="mw-redirect" title="Radio propagation model">Radio frequency propagation models</a></div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Free_space" class="mw-redirect" title="Free space">Free space</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Free-space_path_loss" title="Free-space path loss">Free-space path loss</a></li>

<li><a href="Friis_transmission_equation" title="Friis transmission equation">Friis transmission equation</a></li>

<li><a href="Dipole_field_strength_in_free_space" title="Dipole field strength in free space">Dipole field strength in free space</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Terrain" title="Terrain">Terrain</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="ITU_terrain_model" title="ITU terrain model">ITU terrain model</a></li>

<li><a href="Egli_model" title="Egli model">Egli model</a></li>

<li><a href="Longley%E2%80%93Rice_model" title="Longley–Rice model">Longley–Rice Irregular Terrain Model (ITM)</a></li>

<li><a href="Two-ray_ground-reflection_model" title="Two-ray ground-reflection model">Two-ray ground-reflection model</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Foliage" class="mw-redirect" title="Foliage">Foliage</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Weissberger's_model" title="Weissberger's model">Weissberger's model</a></li>

<li><a href="Early_ITU_model" title="Early ITU model">Early ITU model</a></li>

<li><a href="One_woodland_terminal_model" title="One woodland terminal model">One woodland terminal model</a></li>

<li><a href="Single_vegetative_obstruction_model" title="Single vegetative obstruction model">Single vegetative obstruction model</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Urban_area" title="Urban area">Urban</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Okumura_model" title="Okumura model">Okumura model</a></li>

<li><a href="Hata_model" title="Hata model">Hata model</a></li>

<li><a href="COST_Hata_model" title="COST Hata model">COST Hata model</a></li>

<li><a href="Young_model" title="Young model">Young model</a></li>

<li><a href="Six-rays_model" title="Six-rays model">Six-rays model</a></li>

<li><a href="Ten-rays_model" title="Ten-rays model">Ten-rays model</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Indoor</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="ITU_model_for_indoor_attenuation" title="ITU model for indoor attenuation">ITU model for indoor attenuation</a></li>

<li><a href="Log-distance_path_loss_model" title="Log-distance path loss model">Log-distance path loss model</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Other</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="VOACAP" title="VOACAP">VOACAP</a> (<a href="High_frequency" title="High frequency">HF</a>)</li>

<li><a href="Area-to-area_Lee_model" title="Area-to-area Lee model">Area-to-area Lee model</a> (900 MHz)</li>

<li><a href="Point-to-point_Lee_model" title="Point-to-point Lee model">Point-to-point Lee model</a> (900 MHz)</li>

<li><a href="Longley%E2%80%93Rice_model" title="Longley–Rice model">Longley–Rice model</a> (20 MHz - 20 GHz)</li></ul>

</div></td></tr></tbody></table></div></div><div><div class="zim-footer">

This article is issued from <a class="external text" title="Last edited on 2024-12-02" href="https://en.wikipedia.org/wiki/?title=Path_loss&oldid=1260836445">Wikipedia</a>. The text is available under <a class="external text" href="https://creativecommons.org/licenses/by-sa/4.0/deed.en">Creative Commons Attribution-Share Alike 4.0</a> unless otherwise noted. Additional terms may apply for the media files.

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