Specifications

ETSI

Final draft ETSI EN 300 328 V1.8.1 (2012

04)

= distance between outer boundary of radiated near field (Fresnel region) and inner boundary of the

radiated far-field (Fraunhofer region) in m, also known as Rayleigh distance

For those measurements, where these conditions cannot be fulfilled and where the measurement distance would result in

measurements in the near field (e.g. while measuring spurious emissions), this should be noted in the test report and the

additional measurement uncertainty should be incorporated into the results.

B.2 Antennas

Antennas are needed for the radiated measurements on the three test sites described in clause B.1. Depending on its use,

the antenna will be designated as "measurement antenna" or "substitution antenna".

B.2.1 Measurement antenna

In emission tests the measurement antenna is used to detect the field from the UUT in one stage of the measurement,

and from the substitution antenna in the other stage. When the test site is used for the measurement of receiver

characteristics, the antenna is used as the transmitting device.

The measurement antenna should be mounted on a support capable of allowing the antenna to be used in either

horizontal or vertical polarization. Additionally, on an OATS or SAR, the height of the centre of the antenna above the

ground should be variable over the specified range (usually 1 m to 4 m).

In the frequency band 30 MHz to 1 000 MHz, biconical or logarithmic periodic dipole antennas (LPDA) are

recommended. Above 1 GHz, horn antennas or logarithmic periodic dipole antennas are recommended.

For spurious emission testing, however, a combination of biconical antennas (commonly termed "bicones") and log

periodic dipole array antennas (commonly termed "log periodics") could be used to cover the entire 30 MHz to

1 000 MHz band.

The measurement antenna does not require an absolute calibration.

B.2.2 Substitution antenna

The substitution antenna shall be used to replace the equipment under test in substitution measurements.

Shall be suitable for the frequency range and the return loss of the antenna shall be taken into account when calculating

the measurement uncertainty.

The phase centre of this antenna shall coincide with the reference point of the test sample it has replaced. Therefore

antennas with a phase centre that changes as a function of frequency (such as a LPDA) are not suitable as a substitution

antenna.

The reference point of the substitution antenna shall coincide with the volume centre of the UUT when its antenna is

internal, or the point where an external antenna is connected to the UUT.

The distance between the lower extremity of the antenna and the ground shall be at least 30 cm.

The substitution antenna shall be calibrated for the test site (OATS, SAR, FAR) in which it will be used. For below

1 GHz, the calibration is relative to a half wave dipole, while above 1 GHz, an isotropic radiator is the reference.

NOTE: Calibration figures intended for use above a reflective surface cannot be used in an anechoic chamber or

vice versa.