# Recommendation itu-r sm. 329-9 Spurious emissions

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## 2.1 Power units

Even though the International System (IS) power unit is the Watt (W), the telecommunication publications express spurious emissions p.s.a., e.i.r.p. or e.r.p. in various units including dBpW, nW, dBm or dBW or equivalent expressions of power density per any reference bandwidth.

## 2.2 Field strength units

The electric field strength unit, E, is the V/m. Most of the telecommunication publications express electric field strength in V/m or dB(V/m).

The magnetic field strength unit, H, is the A/m. Most of the telecommunication publications express electric field strength in A/m or dB(A/m).

## 2.3 pfd units

The pfd unit is the W/m2. Most of the telecommunication publications express pfd in dB(W/m2) or in mW/cm2.

## 3 Relation between power, electric field strength, E, and pfd

A simple relation can be established for perfect, ideal cases (which means free space, far field conditions) between E (V/m), D distance between the transmitting radio equipment and the point of measurement (m), e.i.r.p. (W) and pfd (W/m2).

A maximum value of E can be calculated, representing the maximum reading obtainable on an OATS by adjustment of the measurement antenna height. It is:

Emax @ 1.6 E

This represents a site gain of 4 dB. The field strength as E (V/m) can be converted to dB(V/m) as follows:

E (dB(V/m))  120  20 log E

the pfd (W/m2) is:

pfdE2/(120)

and the PFD (dB(W/m2)) is:

PFD  10 log pfd

Table 7 shows the correspondence between the power values (e.i.r.p., e.r.p.), the field strength (EEmax ) and the pfd for different units.
TABLE 7

Correspondence between e.i.r.p., e.r.p., field strength, E, and pfd

 e.i.r.p. (dBm) e.i.r.p. (nW) e.i.r.p. (dB(pW)) e.i.r.p. (dBW) e.r.p. (dBm) E field free space (dB(µV/m)) at 10 m Emax OATS (dB(µV/m)) at 10 m PFD free space (dB(W/m2)) at 10 m PFD maximum OATS (dB(W/m2)) at 10 m –90 0.001 0 –120 –92.15 –5.2 –1.2 –151.0 –147.0 –80 0.01 10 –110 –82.15 4.8 8.8 –141.0 –137.0 –70 0.1 20 –100 –72.15 14.8 18.8 –131.0 –127.0 –60 1 30 –90 –62.15 24.8 28.8 –121.0 –117.0 –50 10 40 –80 –52.15 34.8 38.8 –111.0 –107.0 –40 100 50 –70 –42.15 44.8 48.8 –101.0 –97.0 –30 1 000 60 –60 –32.15 54.8 58.8 –91.0 –87.0 –20 10 000 70 –50 –22.15 64.8 68.8 –81.0 –77.0 –10 100 000 80 –40 –12.15 74.8 78.8 –71.0 –67.0 0 1 000 000 90 –30 –2.15 84.8 88.8 –61.0 –57.0

ANNEX 2

Methods of measurement of spurious domain emissions

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