EMRP

EMRP is effective monopole radiated power (in a given direction) ( English - effective monopole radiated power (EMRP) (in a given direction) ) and - in accordance with Article 1163 of the ITU Radio Regulations (Radio Regulations) of the International Telecommunication Union (ITU) - Defined as «the product of the power supplied to the antenna and its gain , based on a short vertical antenna (often also: ground plane antenna , monopole antenna or Marconi antenna) in a given direction ».

detection

${\displaystyle EMRP={P_{s}\cdot G_{v}}}$

With

• P _s : power fed into the antenna (in watts),
• G _v : Antenna gain compared to a short vertical antenna (dimensionless).

If no direction is specified, the value applies to the main beam direction of the transmitting antenna, in which its antenna gain is also greatest.

A short monopole antenna serves as a reference antenna for the antenna gain. This antenna form - and thus also the EMRP - is only important in the long and medium wave range , since only there vertical self-radiating masts with earth network (monopoles) are used as transmitting antennas.

In practice, the EMRP actually radiated into the ground wave is determined by measurements in the far field of the long or medium wave transmitter . An EMRP of 1 kilowatt, for example, generates an electric field strength of 300 mV / m (corresponding to 109.5 dBµV / m) at a distance of one kilometer from the transmitting antenna.

For internationally coordinated long and medium wave frequencies in the Geneva '75 plan , however, the maximum permitted EMRP of a transmitter is determined by the product of its output power and the theoretical antenna gain of a lossless antenna.

A quarter-wave monopole , which is often used as a transmitting antenna, has a gain of 1.093 (corresponding to 0.39 dB) and a half-wave monopole of 1.6 (corresponding to 2.04 dB), in each case compared to a short monopole over ideally conductive earth.

Connection with ERP and EIRP

EMRP, ERP and EIRP only differ in the reference antenna for the antenna gain:

• if the antenna gain is related to the isotropic radiator , one speaks of EIRP ,
• when referring to a half-wave dipole from ERP .

By definition, a short monopole over an ideally conductive earth has an antenna gain of 1 (corresponding to 0 dB). Compared to an isotropic radiator its gain is 3 (corresponding to 4.77 dBi) and compared to a half-wave dipole 1.83 (corresponding to 2.62 dBd):

${\displaystyle {\begin{aligned}EIRP&=3&&\cdot EMRP\\ERP&=1{,}83&&\cdot EMRP\end{aligned}}}$

Or, for example, in logarithmic units:

${\displaystyle {\frac {EIRP}{\mathrm {dBm} }}={\frac {EMRP}{\mathrm {dBm} }}+{\frac {4{,}77}{\mathrm {dBi} }}}$

${\displaystyle {\frac {ERP}{\mathrm {dBm} }}={\frac {EMRP}{\mathrm {dBm} }}+{\frac {2{,}62}{\mathrm {dBd} }}}$

Spellings

EMRP is often treated like a physical quantity . It is therefore assigned a value. Another possibility is to put EMRP after the unit of measurement in brackets, e.g. B. Watt (EMRP) .

See also

• Transmitter

Individual evidence

1. ↑ VO Funk, Edition 2012, Article 1.163, Definition: Effective monopole radiated power (emrp) (in a given direction) / Effective monopole radiated power (EMRP) (in a given direction)
2. ^ ITU: Recommendation ITU-R BS.561-2, Definitions of radiation in LF, MF and HF broadcasting bands
3. ↑ ITU: final acts of the Regional Administrative LF / MF Broadcasting Conference (Regions 1 and 3), Geneva, 1975, Annex 2, Chapter 4.3 Radiated Power: The radiated power is assumed to be the product of the nominal power of the transmitter and the gain of the antenna (relative to a short vertical antenna) without taking into account any losses *. It is expressed either by the cymomotive force (cmf in V or in dB relative to 300 V) or by the effective monopole radiated power (emrp in kW or in dB relative to 1 kW).
4. ↑ ITU: final acts of the Regional Administrative LF / MF Broadcasting Conference (Regions 1 and 3), Geneva, 1975, Annex 2, Figure 11: Transmitting Antenna Gain for a simple Vertical Antenna
5. ^ Hans Heinrich Meinke , Friedrich-Wilhelm Gundlach : Pocket book of high frequency technology , 4th edition 1985, Springer-Verlag: page N16