Elliott PowerWave 2.4GHz Radio, Manual, Page: 14 / 135

Elliott Laboratories, Inc. -- EMC Department Test Report
Report Date: October 20, 1998
File: R28747 Page 14 of 14 pages
SAMPLE CALCULATIONS - RADIATED EMISSIONS
Receiver readings are compared directly to the specification limit (decibel form). The
receiver internally corrects for cable loss, preamplifier gain, and antenna factor. The
calculations are in the reverse direction of the actual signal flow, thus cable loss is added
and the amplifier gain is subtracted. The Antenna Factor converts the voltage at the antenna
coaxial connector to the field strength at the antenna elements. A distance factor, when
used for electric field measurements, is calculated by using the following formula:
Fd = 20*LOG10 (Dm/Ds)
where:
Fd = Distance Factor in dB
Dm = Measurement Distance in meters
Ds = Specification Distance in meters
Measurement Distance is the distance at which the measurements were taken and
Specification Distance is the distance at which the specification limits are based. The
antenna factor converts the voltage at the antenna coaxial connector to the field strength at
the antenna elements.
The margin of a given emission peak relative to the limit is calculated as follows:
Rc = Rr + Fd
and
M = Rc - Ls
where:
Rr = Receiver Reading in dBuV/m
Fd = Distance Factor in dB
Rc = Corrected Reading in dBuV/m
Ls = Specification Limit in dBuV/m
M = Margin in dB Relative to Spec