Misplaced Pages

#877122

60-564: CIMF-FM has an effective radiated power (ERP) of 84,000 watts . It is a Class C1 station using an omnidirectional antenna located in Camp Fortune, Quebec , within Gatineau Park . The station signed on the air on January 1, 1970. Its original call sign was CKCH-FM as the sister station to the now-defunct CKCH 970 AM. The AM station went silent on September 30, 1994, when the " Telemedia " and "Radiomutuel" networks merged to form

120-403: 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 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

180-497: 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

240-622: 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

300-569: A deal between Telemedia (which then owned CIMF-FM) and Radio-Canada to allow the latter to raise the power of CBF-FM 95.1 MHz in Montreal , Quebec from 17,030 to 100,000 watts. The relay, CIMF-FM-1 in Hawkesbury, operates on 88.9 MHz using a directional antenna with an average effective radiated power of 759 watts and a peak effective radiated power of 1,250 watts ( class A ). *Currently being sold to other owners pending approval of

360-415: A dipole does not imply a comparison of that antenna's gain in each direction to a dipole's gain in that direction. Rather, it is a comparison between the antenna's gain in each direction to the peak gain of the dipole (1.64). In any direction, therefore, such numbers are 2.15 dB smaller than the gain expressed in dBi. Partial gain is calculated as power gain, but for a particular polarization . It

420-400: A distance   r   . {\displaystyle \ r\ .} That amplitude is given by: where: For a large distance   r   . {\displaystyle \ r\ .} The radiated wave can be considered locally as a plane wave. The intensity of an electromagnetic plane wave is: where and If the resistive part of the series impedance of

480-816: 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

540-464: 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

600-399: A given direction to the radiation intensity that would be produced if the power accepted by the antenna were isotropically radiated". Usually this ratio is expressed in decibels with respect to an isotropic radiator (dBi). An alternative definition compares the received power to the power received by a lossless half-wave dipole antenna , in which case the units are written as dBd . Since

660-414: A half-wave dipole with respect to the isotropic radiator is known to be 1.64 and it can be made nearly 100% efficient. Since the gain has been measured with respect to this reference antenna, the difference in the gain of the test antenna is often compared to that of the dipole. The gain relative to a dipole is thus often quoted and is denoted using dBd instead of dBi to avoid confusion. Therefore, in terms of

SECTION 10

#1733085231878

720-431: A lossless dipole antenna has a gain of 2.15 dBi, the relation between these units is G a i n ( d B d ) ≈ G a i n ( d B i ) − 2.15 {\displaystyle \mathrm {Gain(dBd)} \approx \mathrm {Gain(dBi)} -2.15} . For a given frequency, the antenna's effective area is proportional to the gain. An antenna's effective length

780-411: A manufacturer) one must be certain as to whether this means the gain relative to an isotropic radiator or with respect to a dipole. If it specifies dBi or dBd then there is no ambiguity, but if only dB is specified then the fine print must be consulted. Either figure can be easily converted into the other using the above relationship. When considering an antenna's directional pattern, gain with respect to

840-501: A new logo. This resulted in CIMF Rock-Détente being renamed to simply 94,9 RockDétente . As such, the station no longer publicly uses its call sign (although the call letters were brought back as station identification in 2011). On August 18, 2011, at 4 p.m., the station ended its 21-year run with the "RockDétente" branding. All "RockDétente" stations, including CIMF, rebranded as Rouge FM . The last song under "RockDétente"

900-476: A so-called reference antenna at the same distance receiving the same power in order to determine the gain of the antenna under test. That ratio would be equal to G if the reference antenna were an isotropic radiator (irad). However a true isotropic radiator cannot be built, so in practice a different antenna is used. This will often be a half-wave dipole, a very well understood and repeatable antenna that can be easily built for any frequency. The directive gain of

960-423: 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

1020-983: 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

1080-402: 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

1140-417: Is "The ratio of the total power radiated by an antenna to the net power accepted by the antenna from the connected transmitter." A transmitting antenna is supplied with power by a transmission line connecting the antenna to a radio transmitter . The power accepted by the antenna P O {\displaystyle P_{O}} is the power supplied to the antenna's terminals. Losses prior to

1200-422: 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

1260-457: Is a key performance parameter which combines the antenna 's directivity and radiation efficiency . The term power gain has been deprecated by IEEE. In a transmitting antenna, the gain describes how well the antenna converts input power into radio waves headed in a specified direction. In a receiving antenna, the gain describes how well the antenna converts radio waves arriving from a specified direction into electrical power. When no direction

SECTION 20

#1733085231878

1320-538: 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

1380-560: Is defined as the part of the radiation intensity U {\displaystyle U} corresponding to a given polarization, divided by the total radiation intensity of an isotropic antenna. The partial gains in the θ {\displaystyle \theta } and ϕ {\displaystyle \phi } components are expressed as and where U θ {\displaystyle U_{\theta }} and U ϕ {\displaystyle U_{\phi }} represent

1440-414: 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 the same thing is effective isotropic radiated power ( EIRP ). Effective isotropic radiated power

1500-406: 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

1560-888: 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 Antenna gain In electromagnetics , an antenna's gain

1620-484: Is proportional to the square root of the antenna's gain for a particular frequency and radiation resistance . Due to reciprocity , the gain of any antenna when receiving is equal to its gain when transmitting. Gain is a unitless measure that multiplies an antenna's radiation efficiency η {\displaystyle \eta } and directivity D : The radiation efficiency η {\displaystyle \eta } of an antenna

1680-438: 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

1740-422: Is specified, gain is understood to refer to the peak value of the gain, the gain in the direction of the antenna's main lobe . A plot of the gain as a function of direction is called the antenna pattern or radiation pattern . It is not to be confused with directivity, which does not take an antenna's radiation efficiency into account. Gain or 'absolute gain' is defined as "The ratio of the radiation intensity in

1800-412: 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 a theoretical isotropic antenna. Since a half-wave dipole antenna has

1860-475: 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

CIMF-FM - Misplaced Pages Continue

1920-448: 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

1980-424: Is used rather than just dB to emphasize that this is the gain according to the basic definition, in which the antenna is compared to an isotropic radiator. When actual measurements of an antenna's gain are made by a laboratory, the field strength of the test antenna is measured when supplied with, say, 1 watt of transmitter power, at a certain distance. That field strength is compared to the field strength found using

2040-486: 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

2100-481: The " Radiomédia " network (now " Corus Québec "). CKCH-FM, and later CIMF-FM , had a beautiful music format for its first 20 years, playing mostly instrumental cover songs of popular hits. Over time, to stay contemporary, it added more soft vocals. The station switched to soft adult contemporary in 1990 and the station was renamed CIMF Rock-Détente . In 2004, Astral Media revamped the Rock Détente network with

2160-489: The CRTC. 45°26′06″N 75°44′00″W  /  45.43507°N 75.73323°W  / 45.43507; -75.73323 Effective radiated power Effective radiated power ( ERP ), synonymous with equivalent radiated power , 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

2220-1191: 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

2280-619: 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

2340-539: 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

2400-428: 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

2460-442: The antenna is   R s   , {\displaystyle \ {R_{s}}\ ,} the power fed to the antenna is 1 2 R s I 2   . {\displaystyle \scriptstyle {1 \over 2}{R_{s}I^{2}}\ .} The intensity of an isotropic antenna is the power so fed divided by the surface of the sphere of radius r : The directive gain is: For

CIMF-FM - Misplaced Pages Continue

2520-426: 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

2580-420: The antenna terminals are accounted for by separate impedance mismatch factors which are therefore not included in the calculation of radiation efficiency. Published numbers for antenna gain are almost always expressed in decibels (dB), a logarithmic scale. From the gain factor G, one finds the gain in decibels as: Therefore, an antenna with a peak power gain of 5 would be said to have a gain of 7 dBi. dBi

2640-1002: 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

2700-426: 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

2760-568: 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,

2820-475: The commonly utilized half-wave dipole , the particular formulation works out to the following, including its decibel equivalency, expressed as dBi (decibels referenced to isotropic radiator): Sometimes, the half-wave dipole is taken as a reference instead of the isotropic radiator. The gain is then given in dBd (decibels over dipole): Realized gain differs from gain in that it is "reduced by its impedance mismatch factor." This mismatch induces losses above

2880-403: 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

2940-473: 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

3000-551: The dissipative losses described above; therefore, realized gain will always be less than gain. Gain may be expressed as absolute gain if further clarification is required to differentiate it from realized gain. Total radiated power (TRP) is the sum of all RF power radiated by the antenna when the source power is included in the measurement. TRP is expressed in watts or the corresponding logarithmic expressions, often dBm or dBW. When testing mobile devices, TRP can be measured while in close proximity of power-absorbing losses such as

3060-434: 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

SECTION 50

#1733085231878

3120-527: The peak radiation intensity of this antenna: The total radiated power can be found by integrating over all directions: Since the antenna is specified as being lossless the radiation efficiency is 1. The maximum gain is then equal to: Expressed relative to the gain of a half-wave dipole we would find: As an example, consider an antenna that radiates an electromagnetic wave whose electrical field has an amplitude   E θ   {\displaystyle \ E_{\theta }\ } at

3180-428: 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

3240-441: 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

3300-407: The radiation intensity in a given direction contained in their respective E {\displaystyle E} field component. As a result of this definition, we can conclude that the total gain of an antenna is the sum of partial gains for any two orthogonal polarizations. Suppose a lossless antenna has a radiation pattern given by: Let us find the gain of such an antenna. First we find

3360-449: 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

3420-464: 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,

3480-401: The true gain (relative to an isotropic radiator) G , this figure for the gain is given by: For instance, the above antenna with a gain G = 5 would have a gain with respect to a dipole of 5/1.64 ≈ 3.05, or in decibels one would call this 10 log(3.05) ≈ 4.84 dBd. In general: Both dBi and dBd are in common use. When an antenna's maximum gain is specified in decibels (for instance, by

3540-789: 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

3600-462: Was " Pour que tu m'aimes encore " by Celine Dion , followed by a tribute of the branding. The first song under "Rouge" was " I Gotta Feeling " by Black Eyed Peas . On October 31, 2000, Télémédia Radio was denied a licence to add a new FM transmitter to operate on 107.7 MHz at Hawkesbury , Ontario . Since 2001, the station operated a relay transmitter in Hawkesbury, Ontario, approximately 100 kilometres east of Ottawa/Gatineau. This results from

#877122