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41-680: The station has an effective radiated power of 6,000 watts . The studios, offices and transmitter are off South Philip Road in Niles, Michigan . WSMK signed on the air in 1991. It was an urban contemporary station known as "Smokin 99.1". This was the second urban station in the Michiana area, the first having been the former WLLJ (910 AM) in Cassopolis , which later switched to oldies as WGTO . On February 4, 2005, WYPW (95.7 FM), formerly adult contemporary WLRX, became "Power 95.7"; it

82-424: A radio antennas , the main lobe or main beam is the region of the radiation pattern containing the highest power or exhibiting the greatest field strength . The radiation pattern of most antennas shows a pattern of " lobes " at various directions, where the radiated signal strength reaches a local maximum, separated by " nulls ", at which the radiation falls to zero. In a directional antenna in which

123-497: A waiver , and can exceed normal restrictions. For most microwave systems, a completely non-directional isotropic antenna (one which radiates equally and perfectly well in every direction – a physical impossibility) is used as a reference antenna, and then one speaks of EIRP (effective isotropic radiated power) rather than ERP. This includes satellite transponders , radar, and other systems which use microwave dishes and reflectors rather than dipole-style antennas. In

164-622: A cellular telephone tower has a fixed linear polarization, but the mobile handset must function well at any arbitrary orientation. Therefore, a handset design might provide dual polarization receive on the handset so that captured energy is maximized regardless of orientation, or the designer might use a circularly polarized antenna and account for the extra 3 dB of loss with amplification. For example, an FM radio station which advertises that it has 100,000 watts of power actually has 100,000 watts ERP, and not an actual 100,000-watt transmitter. The transmitter power output (TPO) of such

205-464: A gain of 1× (equiv. 0 dBi). So ERP and EIRP are measures of radiated power that can compare different combinations of transmitters and antennas on an equal basis. In spite of the names, ERP and EIRP do not measure transmitter power, or total power radiated by the antenna, they are just a measure of signal strength along the main lobe. They give no information about power radiated in other directions, or total power. ERP and EIRP are always greater than

246-423: A station typically may be 10,000–20,000 watts, with a gain factor of 5–10× (5–10×, or 7–10  dB ). In most antenna designs, gain is realized primarily by concentrating power toward the horizontal plane and suppressing it at upward and downward angles, through the use of phased arrays of antenna elements. The distribution of power versus elevation angle is known as the vertical pattern . When an antenna

287-886: A theoretical isotropic antenna. Since a half-wave dipole antenna has a gain of 1.64 (or 2.15 dB ) compared to an isotropic radiator, if ERP and EIRP are expressed in watts their relation is   E I R P ( W ) = 1.64 × E R P ( W )   {\displaystyle \ {\mathsf {EIRP}}_{\mathsf {(W)}}=1.64\times {\mathsf {ERP}}_{\mathsf {(W)}}\ } If they are expressed in decibels   E I R P ( d B ) = E R P ( d B ) + 2.15   d B   {\displaystyle \ {\mathsf {EIRP}}_{\mathrm {(dB)} }={\mathsf {ERP}}_{\mathrm {(dB)} }+2.15\ {\mathsf {dB}}\ } Effective radiated power and effective isotropic radiated power both measure

328-983: Is   E I R P ( d B W ) = P T X   ( d B W ) − L ( d B ) + G ( d B i )   , {\displaystyle \ {\mathsf {EIRP}}_{\mathsf {(dB_{W})}}=P_{{\mathsf {TX}}\ {\mathsf {(dB_{W})}}}-L_{\mathsf {(dB)}}+G_{\mathsf {(dB_{i})}}\ ,}   E R P ( d B W ) = P T X   ( d B W ) − L ( d B ) + G ( d B i ) − 2.15   d B   . {\displaystyle \ {\mathsf {ERP}}_{\mathsf {(dB_{W})}}=P_{{\mathsf {TX}}\ {\mathsf {(dB_{W})}}}-L_{\mathsf {(dB)}}+G_{\mathsf {(dB_{i})}}-2.15\ {\mathsf {dB}}~.} Losses in

369-402: Is 8.77 dB d = 10.92 dB i . Its gain necessarily must be less than this by the factor η, which must be negative in units of dB. Neither ERP nor EIRP can be calculated without knowledge of the power accepted by the antenna, i.e., it is not correct to use units of dB d or dB i with ERP and EIRP. Let us assume a 100 watt (20 dB W ) transmitter with losses of 6 dB prior to

410-422: Is a constant, i.e., 0 dB d = 2.15 dB i . Therefore, ERP is always 2.15 dB less than EIRP. The ideal dipole antenna could be further replaced by an isotropic radiator (a purely mathematical device which cannot exist in the real world), and the receiver cannot know the difference so long as the input power is increased by 2.15 dB. The distinction between dB d and dB i is often left unstated and

451-538: Is also directional horizontally, gain and ERP will vary with azimuth ( compass direction). Rather than the average power over all directions, it is the apparent power in the direction of the peak of the antenna's main lobe that is quoted as a station's ERP (this statement is just another way of stating the definition of ERP). This is particularly applicable to the huge ERPs reported for shortwave broadcasting stations, which use very narrow beam widths to get their signals across continents and oceans. ERP for FM radio in

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492-411: Is an IEEE standardized definition of directional radio frequency (RF) power, such as that emitted by a radio transmitter . It is the total power in watts that would have to be radiated by a half-wave dipole antenna to give the same radiation intensity (signal strength or power flux density in watts per square meter) as the actual source antenna at a distant receiver located in the direction of

533-406: Is larger it will be used instead. The maximum ERP for US FM broadcasting is usually 100,000 watts (FM Zone II) or 50,000 watts (in the generally more densely populated Zones I and I-A), though exact restrictions vary depending on the class of license and the antenna height above average terrain (HAAT). Some stations have been grandfathered in or, very infrequently, been given

574-803: Is possible for a station of only a few hundred watts ERP to cover more area than a station of a few thousand watts ERP, if its signal travels above obstructions on the ground. ELF 3 Hz/100 Mm 30 Hz/10 Mm SLF 30 Hz/10 Mm 300 Hz/1 Mm ULF 300 Hz/1 Mm 3 kHz/100 km VLF 3 kHz/100 km 30 kHz/10 km LF 30 kHz/10 km 300 kHz/1 km MF 300 kHz/1 km 3 MHz/100 m HF 3 MHz/100 m 30 MHz/10 m VHF 30 MHz/10 m 300 MHz/1 m UHF 300 MHz/1 m 3 GHz/100 mm SHF 3 GHz/100 mm 30 GHz/10 mm EHF 30 GHz/10 mm 300 GHz/1 mm THF 300 GHz/1 mm 3 THz/0.1 mm Main lobe In

615-438: Is quantified by the antenna gain , which is the ratio of the signal strength radiated by an antenna in its direction of maximum radiation to that radiated by a standard antenna. For example, a 1,000 watt transmitter feeding an antenna with a gain of 4× (equiv. 6 dBi) will have the same signal strength in the direction of its main lobe, and thus the same ERP and EIRP, as a 4,000 watt transmitter feeding an antenna with

656-481: Is the same as ERP, except that a short vertical antenna (i.e. a short monopole ) is used as the reference antenna instead of a half-wave dipole . Cymomotive force ( CMF ) is an alternative term used for expressing radiation intensity in volts , particularly at the lower frequencies. It is used in Australian legislation regulating AM broadcasting services, which describes it as: "for a transmitter, [it] means

697-448: Is typical for medium or longwave broadcasting, skywave , or indirect paths play a part in transmission, the waves will suffer additional attenuation which depends on the terrain between the antennas, so these formulas are not valid. Because ERP is calculated as antenna gain (in a given direction) as compared with the maximum directivity of a half-wave dipole antenna , it creates a mathematically virtual effective dipole antenna oriented in

738-486: Is usually connected to the antenna through a transmission line and impedance matching network . Since these components may have significant losses   L   , {\displaystyle \ L\ ,} the power applied to the antenna is usually less than the output power of the transmitter   P T X   . {\displaystyle \ P_{\mathsf {TX}}~.} The relation of ERP and EIRP to transmitter output power

779-403: The " backlobe ". The radiation pattern referred to above is usually the horizontal radiation pattern, which is plotted as a function of azimuth about the antenna, although the vertical radiation pattern may also have a main lobe. The beamwidth of the antenna is the width of the main lobe, usually specified by the half power beam width (HPBW), the angle encompassed between the points on

820-431: The "Smokin' 99.1" slogan. The station's website, at the time, said it featured such artists as Beyoncé , Usher , Jay-Z , Katy Perry , Lady Gaga , Eminem , Rihanna and Nicki Minaj . 41°49′23.5″N 86°17′2.6″W  /  41.823194°N 86.284056°W  / 41.823194; -86.284056 Effective radiated power Effective radiated power ( ERP ), synonymous with equivalent radiated power ,

861-1195: The EIRP or ERP. Since an isotropic antenna radiates equal power flux density over a sphere centered on the antenna, and the area of a sphere with radius   r   {\displaystyle \ r\ } is   A = 4 π   r 2   {\displaystyle \ A=4\pi \ r^{2}\ } then   S ( r ) =   E I R P     4 π   r 2     . {\displaystyle \ S(r)={\frac {\ {\mathsf {EIRP}}\ }{\ 4\pi \ r^{2}\ }}~.} Since   E I R P = E R P × 1.64   , {\displaystyle \ \mathrm {EIRP} =\mathrm {ERP} \times 1.64\ ,}   S ( r ) =   0.410 × E R P     π   r 2     . {\displaystyle \ S(r)={\frac {\ 0.410\times {\mathsf {ERP}}\ }{\ \pi \ r^{2}\ }}~.} After dividing out

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902-632: The FCC database shows the station's transmitter power output, not ERP. According to the Institution of Electrical Engineers (UK), ERP is often used as a general reference term for radiated power, but strictly speaking should only be used when the antenna is a half-wave dipole, and is used when referring to FM transmission. Effective monopole radiated power ( EMRP ) may be used in Europe, particularly in relation to medium wave broadcasting antennas. This

943-559: The United States is always relative to a theoretical reference half-wave dipole antenna. (That is, when calculating ERP, the most direct approach is to work with antenna gain in dB d ). To deal with antenna polarization, the Federal Communications Commission (FCC) lists ERP in both the horizontal and vertical measurements for FM and TV. Horizontal is the standard for both, but if the vertical ERP

984-428: The actual total power radiated by the antenna. The difference between ERP and EIRP is that antenna gain has traditionally been measured in two different units, comparing the antenna to two different standard antennas; an isotropic antenna and a half-wave dipole antenna: In contrast to an isotropic antenna, the dipole has a "donut-shaped" radiation pattern, its radiated power is maximum in directions perpendicular to

1025-426: The antenna itself are included in the gain. If the signal path is in free space ( line-of-sight propagation with no multipath ) the signal strength ( power flux density in watts per square meter)   S   {\displaystyle \ S\ } of the radio signal on the main lobe axis at any particular distance r {\displaystyle r} from the antenna can be calculated from

1066-505: The antenna's strongest beam ( main lobe ). ERP measures the combination of the power emitted by the transmitter and the ability of the antenna to direct that power in a given direction. It is equal to the input power to the antenna multiplied by the gain of the antenna. It is used in electronics and telecommunications , particularly in broadcasting to quantify the apparent power of a broadcasting station experienced by listeners in its reception area. An alternate parameter that measures

1107-1002: The antenna, declining to zero on the antenna axis. Since the radiation of the dipole is concentrated in horizontal directions, the gain of a half-wave dipole is greater than that of an isotropic antenna. The isotropic gain of a half-wave dipole is 1.64, or in decibels   10   log 10 ⁡ ( 1.64 ) = 2.15   d B   , {\displaystyle \ 10\ \log _{10}(1.64)=2.15\ {\mathsf {dB}}\ ,} so   G i = 1.64   G d   . {\displaystyle \ G_{\mathsf {i}}=1.64\ G_{\mathsf {d}}~.} In decibels   G ( d B i ) = G ( d B d ) + 2.15   d B   . {\displaystyle \ G_{\mathsf {(dB_{i})}}=G_{\mathsf {(dB_{d})}}+2.15\ {\mathsf {dB}}~.} The two measures EIRP and ERP are based on

1148-426: The antenna. ERP < 22.77 dB W and EIRP < 24.92 dB W , both less than ideal by η in dB. Assuming that the receiver is in the first side-lobe of the transmitting antenna, and each value is further reduced by 7.2 dB, which is the decrease in directivity from the main to side-lobe of a Yagi–Uda. Therefore, anywhere along the side-lobe direction from this transmitter, a blind receiver could not tell

1189-575: The case of medium wave (AM) stations in the United States , power limits are set to the actual transmitter power output, and ERP is not used in normal calculations. Omnidirectional antennas used by a number of stations radiate the signal equally in all horizontal directions. Directional arrays are used to protect co- or adjacent channel stations, usually at night, but some run directionally continuously. While antenna efficiency and ground conductivity are taken into account when designing such an array,

1230-403: The difference if a Yagi–Uda was replaced with either an ideal dipole (oriented towards the receiver) or an isotropic radiator with antenna input power increased by 1.57 dB. Polarization has not been taken into account so far, but it must be properly clarified. When considering the dipole radiator previously we assumed that it was perfectly aligned with the receiver. Now assume, however, that

1271-476: The direction of the receiver. In other words, a notional receiver in a given direction from the transmitter would receive the same power if the source were replaced with an ideal dipole oriented with maximum directivity and matched polarization towards the receiver and with an antenna input power equal to the ERP. The receiver would not be able to determine a difference. Maximum directivity of an ideal half-wave dipole

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1312-434: The factor of   π   , {\displaystyle \ \pi \ ,} we get:   S ( r ) =   0.131 × E R P     r 2     . {\displaystyle \ S(r)={\frac {\ 0.131\times {\mathsf {ERP}}\ }{\ r^{2}\ }}~.} However, if the radio waves travel by ground wave as

1353-406: The objective is to emit the radio waves in one direction, the lobe in that direction is designed to have higher field strength than the others, so on a graph of the radiation pattern it appears biggest; this is the main lobe. The other lobes are called " sidelobes ", and usually represent unwanted radiation in undesired directions. The sidelobe in the opposite direction from the main lobe is called

1394-428: The power density a radio transmitter and antenna (or other source of electromagnetic waves) radiate in a specific direction: in the direction of maximum signal strength (the " main lobe ") of its radiation pattern. This apparent power is dependent on two factors: The total power output and the radiation pattern of the antenna – how much of that power is radiated in the direction of maximal intensity. The latter factor

1435-441: The product, expressed in volts, of: It relates to AM broadcasting only, and expresses the field strength in " microvolts per metre at a distance of 1 kilometre from the transmitting antenna". The height above average terrain for VHF and higher frequencies is extremely important when considering ERP, as the signal coverage ( broadcast range ) produced by a given ERP dramatically increases with antenna height. Because of this, it

1476-449: The reader is sometimes forced to infer which was used. For example, a Yagi–Uda antenna is constructed from several dipoles arranged at precise intervals to create greater energy focusing (directivity) than a simple dipole. Since it is constructed from dipoles, often its antenna gain is expressed in dB d , but listed only as dB. This ambiguity is undesirable with respect to engineering specifications. A Yagi–Uda antenna's maximum directivity

1517-464: The receiving antenna is circularly polarized, and there will be a minimum 3 dB polarization loss regardless of antenna orientation. If the receiver is also a dipole, it is possible to align it orthogonally to the transmitter such that theoretically zero energy is received. However, this polarization loss is not accounted for in the calculation of ERP or EIRP. Rather, the receiving system designer must account for this loss as appropriate. For example,

1558-442: The same thing is effective isotropic radiated power ( EIRP ). Effective isotropic radiated power is the hypothetical power that would have to be radiated by an isotropic antenna to give the same ("equivalent") signal strength as the actual source antenna in the direction of the antenna's strongest beam. The difference between EIRP and ERP is that ERP compares the actual antenna to a half-wave dipole antenna, while EIRP compares it to

1599-480: The side of the lobe where the power has fallen to half (-3 dB ) of its maximum value. The concepts of main lobe and sidelobes also apply to acoustics and optics , and are used to describe the radiation pattern of optical systems like telescopes , and acoustic transducers like microphones and loudspeakers . [REDACTED]  This article incorporates public domain material from Federal Standard 1037C . General Services Administration . Archived from

1640-789: The two different standard antennas above: Since the two definitions of gain only differ by a constant factor, so do ERP and EIRP   E I R P ( W ) = 1.64 × E R P ( W )   . {\displaystyle \ {\mathsf {EIRP}}_{\mathsf {(W)}}=1.64\times {\mathsf {ERP}}_{\mathsf {(W)}}~.} In decibels   E I R P ( d B W ) = E R P ( d B W ) + 2.15   d B   . {\displaystyle \ {\mathsf {EIRP}}_{\mathsf {(dB_{W})}}={\mathsf {ERP}}_{\mathsf {(dB_{W})}}+2.15\ {\mathsf {dB}}~.} The transmitter

1681-473: Was in direct competition with "Smokin 99" for urban and hip hop music listeners. (WYPW is now Catholic radio WRDI .) In 2006, WSMK decided to tweak its format to a rhythmic adult contemporary approach and became "Movin 99.1, Michana's Greatest Hits", with the format delivered via satellite from Waitt Radio Networks . In October 2010, with WYPW changing to classic rock as WAOR, 99.1 WSMK transitioned back to locally originating programming and brought back

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