Notice 2020 - DRS0014

Aug 18, 2020

Updated January 4, 2022

Alternate measurement procedure to demonstrate compliance with the Total Radiated Power (TRP) limits

This notice provides alternate measurement procedures to those listed in KDB 842590 D01 for measuring TRP.

1. Background

Within certain radio standard specifications (RSS), the limits for output power and unwanted emissions for Active Antenna Systems (AAS) are defined in terms of TRP. To provide the industry with a measurement methodology, ISED adopted the methods contained within FCC KDB 842590 D01.

The methodology referenced above is intended for the measurement of TRP of millimeter Wave (mmWave) devices. An issue that has been expressed by a number of manufacturers is that the methods of the KDB require the measurements to be in the far-field. Due to the size of the antenna arrays, the far-field distances are greater than the measurement distance of typical shielded chambers used for compliance testing making it impractical to perform direct far-field evaluations.

In addition to the difficulty with the far-field distance, a number of manufacturers have indicated that it is possible to connect directly to the transceiver ports prior to the antenna array. This would allow conducted measurements to be performed.

2. Alternate test methods

2.1 Alternate method 1 - Alternate test site

To facilitate radiated TRP measurements without being in the far-field, a Compact Antenna Test Range (CATR) could be used as an alternate test site. A CATR is designed to transform spherical radiated fields into plane waves, and allows measurements to be performed in a simulated far-field configuration. ISED will allow the use of a CATR as long as the parameters below are met.

2.1.1 CATR minimum specifications

  • Frequency range 1-18 GHz (other frequencies can be measured via traditional direct far-field methods);
  • Quiet zone size large enough to encompass the entire device under test;
  • Cross polarization isolation > 20 dB;
  • Amplitude ripple < ± 0.5 dB;
  • Amplitude taper < 1 dB;
  • Phase ripple < ± 5°;
  • Phase taper < ± 22.5°.

2.2 Alternate method 2 - Conducted measurements

When a connection to the transceiver port can be made, conducted measurements will be permitted as long as the following are met:

  • Measurement methodologies for performing conducted measurements shall follow the normative measurement procedures of ANSI C63.26-2015. This includes, but is not limited to, the following clauses:
    • section 5.2 for output power;
    • section 5.7 for unwanted emissions;
    • section 6.4 for combining emissions from multiple outputs.
  • Output power shall be configured to its maximum tunable level for each of the ports during testing
  • The measurement equipment shall have the same characteristic impedance as the transceiver port (typically 50 ohms) to avoid any mismatch
  • The test report shall also contain cabinet radiation test results performed as specified in ANSI C63.26-2015, section 5.5.

3. Contact details

Should you have any questions, please submit them to the Certification and Engineering Bureau at the following email address