TRP Measurement — CTIA OTA Test Plan / 3GPP OTA Methods

What Is TRP?

TRP (total radiated power) measurement is the measurement in which the total power emitted by the antenna is determined by integrating the power density measured in defined angle steps on the sphere around the device.

Purpose of TRP

The purpose is to determine the actual radiated power of the device, including antenna efficiency, and verify that it meets operator or regulatory requirements.

Which Products Is TRP Applied To?

Cellular devices and modules
Wi-Fi and short range devices
Vehicle-mounted and body-integrated antenna devices
Millimeter wave devices

In Which Sectors Is TRP Used?

TelecommunicationsElectronicsSoftwareCyber Security

Standards Related to TRP

CTIA OTA Test Plan
3GPP TS 38.521-2
IEEE Std 149
ETSI OTA measurement methods

TRP Conditions

Screening: Spherical; with standard defined angle steps
Kutuplanma: Two perpendicular polarizations at each measurement point
Integration: Integration of measured power densities on the sphere
Calibration: Path loss calibration with reference antenna

Equipment for TRP

Antiglare chamber and spherical positioner
Network emulator or signal source
Calibrated measuring antenna and reference dipoles
Measurement and integration software

Sample Requirements for TRP

The device must be able to transmit continuously at maximum power.
The device must be in the orientation defined in the locator
Room and path loss calibration must be up to date
Angle step must be at the resolution defined in the standard

Duration of TRP

Days to weeks depending on the number of tapes and scripts.

TRP Procedure

1The room path loss is calibrated with the reference antenna.
2The device is installed on the positioner and put into transmission.
3Global scanning is done in two polarizations.
4TRP is calculated by integrating power densities.
5The result is reported on a band-by-band basis.

TRP Acceptance Criteria

The acceptance criterion is given as the minimum TRP value in the operator acceptance plans or in the specification.

Evaluation of Results

Insufficient angle resolution creates integration errors; Antennas with sharp radiation patterns require finer pitch. TRP is different from conductor power and includes antenna efficiency.

TRP Report

Implemented test plan
Device and antenna description
Calibration records and angle step
TRP results by band
Measurement uncertainty

Accreditation

EUROLAB holds internationally recognised accreditation obtained from accreditation bodies party to the IAF and ILAC multilateral recognition arrangements, under ISO/IEC 17025 for laboratory testing, ISO/IEC 17020 for inspection and surveillance, and ISO/IEC 17021-1 and ISO/IEC 17065 for system and product certification. This chain ensures the reports and certificates issued are accepted worldwide.

Whether this test can be offered within accredited scope depends on your product and the standard applied; since accreditation is method-based, the scope is confirmed in writing at the quotation stage.

Scope and authorisations

Related Regulations

Operator acceptance programs
Radio Equipment Directive 2014/53/EU (where applicable)

RF and Wireless Testing — What Does This Testing Field Cover?

The section below describes the field that the TRP test belongs to; the conditions and acceptance criteria of this particular test are given in the sections above. The scope specific to your product is confirmed in writing at the quotation stage.

RF and wireless testing shows that a device containing a radio uses the spectrum correctly and operates within the limits the relevant legislation allows. This family is a separate body of work from EMC: EMC addresses unwanted interference, whereas here INTENTIONAL emission is assessed.

Spectrum is a public and limited resource, and this determines the legal character of the field. A device spilling outside its permitted band or emitting excess power is not merely a technical defect but a violation that disrupts someone else's service. Radio conformity is therefore policed more strictly than other test fields and markets maintain their own national regimes.

Measurements run separately on the transmitter and receiver sides. On the transmitter side, output power, occupied bandwidth, frequency error, unwanted emissions, adjacent channel power and the power envelope are measured. On the receiver side, sensitivity, selectivity, blocking and spurious response rejection are assessed. The receiver side is often neglected, but in some bands it is a regulatory requirement.

Access protocol specific behaviours are a third axis: listen before talk (LBT), duty cycle, dynamic frequency selection (DFS) and transmit power control (TPC). These mechanisms enable spectrum sharing and it must be shown that they work correctly.

HUMAN EXPOSURE is the fourth axis and one of the most commercially critical. For devices used close to the body, SAR (specific absorption rate) is measured; for devices used at a distance, a field strength assessment is made. Limits and measurement methods vary by market; the same device is assessed separately for Europe and the United States.

Market regimes are decisive in this family and do not substitute for one another: the Radio Equipment Directive and ETSI harmonised standards in Europe, FCC authorisation in the United States (through a TCB for intentional radiators), ISED in Canada, MIC in Japan, KC in South Korea and SRRC in China each carry their own set of requirements. The same device requires a separate file for each market, and some markets impose a local representative or local testing requirement.

Module integration is the subject that raises the most questions in the field. Using a certified radio module does not automatically make the device compliant. A module certificate is valid for a defined antenna, a defined supply and defined conditions of use; if the antenna changes, the layout changes or the module is operated at a different power level, reassessment is required.

The presence of several radios in the same device (Wi-Fi + Bluetooth + cellular + NFC) gives rise to a simultaneous transmission assessment: SAR and unwanted emission measurements are made for the worst case in which the radios operate together.

Method groups in this field

Transmitter measurements
Output power, occupied bandwidth, frequency error, unwanted emissions, adjacent channel power, power spectral density.
Receiver measurements
Sensitivity, selectivity, blocking, spurious response rejection.
Spectrum sharing mechanisms
Verification of listen before talk, duty cycle, dynamic frequency selection and transmit power control.
Human exposure
SAR measurement (handheld and body-worn devices), field strength assessment, multi-radio scenarios.
Protocol conformity
Cellular network conformity testing, Bluetooth and Wi-Fi certification testing, GNSS performance.
Antenna measurements
Gain, radiation pattern, efficiency and total radiated power (TRP) measurements.

Commonly confused in this field

Using a certified module does not automatically make the device compliant; if the antenna, layout or power level changes, reassessment is required.
An FCC file does not replace a CE file; each market operates its own regime.
Receiver side measurements are a regulatory requirement in some bands; measuring only the transmitter produces an incomplete file.
SAR limits and measurement methods differ by market; a result in one market does not carry over to another.
For devices carrying several radios the simultaneous transmission scenario must be assessed; measuring them individually is not sufficient.
Some markets impose local testing or a local representative requirement; technical conformity alone does not secure market access.

Which decisions these results support

Market access under radio equipment legislation
Verification of the antenna and RF front end design
SAR and RF exposure conformity
Verification of module integration and the scope of reassessment
Determining the worst case in multi-radio scenarios

Related Tests

Frequently Asked Questions About TRP

According to which standard is TRP made?

TRP is executed in scope CTIA OTA Test Plan, 3GPP TS 38.521-2, IEEE Std 149 and ETSI OTA measurement methods. The limit values and acceptance criteria to be applied are defined in the product standard; The version valid for your product is confirmed in writing at the offer stage.

Which products does TRP apply to?

Mainly applied to Cellular devices and modules, Wi-Fi and short range devices, Vehicle-mounted and body-integrated antenna devices and Millimeter wave devices. Whether your product is included in the scope is determined by examining its technical specifications and intended use.

Under what conditions is TRP done?

The determining parameters are: Screening — Spherical; with standard defined angle steps, Kutuplanma — Two perpendicular polarizations at each measurement point and Integration — Integration of measured power densities on the sphere. The full terms are in the "Test Conditions" section on the page and vary depending on the product standard.

What kind of sample is needed for TRP?

The device must be able to transmit continuously at maximum power., The device must be in the orientation defined in the locator and Room and path loss calibration must be up to date. The number of samples is determined according to the product standard and the scope to be reported.

How long does TRP take?

Days to weeks depending on the number of tapes and scripts. This duration belongs to the experiment itself; sample preparation, queuing and reporting are also evaluated. A realistic schedule for your product is given in the offer.

What is the TRP result called "appropriate"?

The acceptance criterion is given as the minimum TRP value in the operator acceptance plans or in the specification.