Manual

ANSI C63.17-2006
Methods of Measurement of the Electromagnetic and Operational Compatibility of UPCS Devices
B.2.4
B.3
B.3.1
Separate transmit and monitoring antennas
The EUT monitoring antenna shall provide coverage, equivalent to the EUT transmit antenna, that may
result in further correction to the monitoring threshold. The following definition of equivalent coverage is
adopted.
The monitoring system shall cause deference to any transmission of sufficient strength to induce a power
level in the EUT transmit antenna that exceeds the maximum threshold allowed for the system under test,
measured at the transmit antenna input.
In applying this principle to develop tests for equivalent coverage, the following assumptions are made:
a) Distance between the transmit and monitoring antennas is not specified in the rules and
therefore is determined by the system designer.
b) There is no requirement that the gain and pattern characteristics of the transmit and monitoring
antennas be identical.
c) Reciprocity exists between transmit and receive gain and pattern characteristics of the transmit
antenna, and the transmit antenna is essentially a lossless radiator.
To verify that the monitoring antenna has coverage equivalent to that of the transmitting antenna, it is
necessary to demonstrate that the EUT defers if a received signal is sufficiently strong to generate an at-
threshold power level at the transmit antenna terminals, unless the transmit and receive antennas are
substantially identical and are collocated.
Transmit power and monitoring threshold test method selection
Practical procedures to demonstrate compliance with the transmit power and monitoring threshold limits
depend on the availability of the antenna terminals for measurements and the relationship between the
transmit and monitoring antennas.
Detachable transmit and monitoring antennas
If a single antenna performs both transmission and monitoring functions, or the transmit and monitoring
antennas are separate but identical and collocated, the equivalent coverage requirements are always met. In
this case, when the EUT antenna is detachable or can be replaced by a connector (and matching circuit, if
necessary), testing to demonstrate compliance with the output power and threshold limits requires
determination of the antenna gain in the direction of maximum radiation, and conducted measurements of
the EUT transmit power and monitoring threshold at the antenna terminals. The antenna gain in the
direction of maximum radiation is determined from typical antenna measurements or manufacturer’s
declaration. It may be possible to measure the EUT gain in facilities that measure radiated power, such as a
wideband TEM cell. In this case, the correlation should be demonstrated with free-space antenna
measurements. Detailed threshold measurements are described in Clause 7.
When the EUT transmit and monitoring antennas are detachable, but different and collocated, the threshold
limit must also account for the equivalent transmit/monitoring antenna coverage. The coverage
measurements can be performed with a reference antenna illuminating the EUT transmit and monitoring
antennas, maintaining a controlled receive power level at the EUT transmit antenna terminals; the level at
the monitor antenna is uncontrolled but the implemented threshold must be chosen by the manufacturer to
cause deferral for all levels for which the level at the transmit antenna is above the appropriate margined
threshold. The test is done with horizontally and vertically polarized reference antennas for a limited
number of EUT orientations. Corresponding procedures can be devised when the tests are made at radiated
power-measuring facilities (e.g., a wideband TEM cell).
52
Copyright © 2007 IEEE. All rights reserved.
Licensed to Sid Sanders. ANSI order X_30788. Downloaded 11/19/2007 2:45 PM. Single user license only. Copying and networking prohibited.