Specifications

EMC-CS-2009.1

February 11, 2010

Where:

, η

= Antenna efficiency factors for the transmit and receive antenna which can be assumed to be 0.75 for a log

periodic antenna and 0.9 for a horn antenna.

V = Chamber volume (m

)

λ = Wavelength at the specific frequency

CCF = Chamber Calibration Factor

If the CLF was assumed to be one (1) from step C2 g), the ACF from C1.1.2 shall be used in place of the CCF when

computing chamber Q.

b) Determine the chamber time constant, t, for every frequency using the following:

fπ2

τ =

Where:

Q = Value calculated in step a) above

f = Test frequency (Hz)

If τ > (0.4 * the pulse width) given in 3.4.3 for more than 10% of the test frequencies, absorber material must be added

and the Q measurement must be repeated. The CLF calculations must be repeated if absorber material is to be added.

Table C-1: Independent Samples and Frequencies for RI 114 Reverberation Method

Frequency Range

(MHz)

Number Of Samples

(i.e. independent tuner positions or

intervals) Recommended for

Calibration and Test)

Number Of Frequencies

(logarithmically spaced)

Required for Calibration

400 to 1000 12 20

1000 to 4000 6 15

> 4000 6 20/decade

Calibration shall consist of eight probe locations below 10 fs (4000 MHz) and three locations above 10 fs (4000 MHz).

The locations selected shall enclose the "working volume" as shown above. The working volume should be located at least 1 meter from

the chamber walls, mode tuning device, and transmitting antenna.

The receive antenna must be located in the working volume for calibration purposes as described in C1.1.1 c). The transmit antenna shall

be pointed into a corner at least 0.25 m away from the chamber surface. The transmit antenna shall remain in a fixed location for all

calibrations and testing.

The working volume may be sized to suit the size of the DUTs to be tested.

The minimum separation distance may be reduced less than 1 m provided that the separation distance is always at least 0.25 m.