Antenna active test

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Antenna active test

At present, more and more attention is paid to the radiation performance test of the whole machine in the radio frequency performance test of the mobile phone, which reflects the final transmission and reception performance of the mobile phone. At present, there are two main methods to investigate the radiation performance of mobile phones.

1. One is to judge from the radiation performance of the antenna, which is the more traditional antenna test method, called passive test;

The other is to test the radiation power and receiving sensitivity of the mobile phone in a specific microwave dark room, which is called active test. OTA(Over The Air) test is an active test.

Active (OTA) test: The test using the comprehensive tester is called active test (Active). The test speed using active test is relatively slow compared with passive test. However, because the mobile phone is a complex material body, passive test is often credible to simulate the transmission performance. However, for the reception performance, only a general reference can be made, and in some special cases, it is not even consistent at all. So now the mobile phone general test active, can be more intuitive and accurate response to the performance of the mobile phone antenna. The general test parameters are as follows:

Transmitted power (TRP): obtained by area integration and averaging of the emitted power of the entire radiating sphere. It reflects the transmission power of the whole mobile phone, and is related to the transmission power and antenna radiation performance of the mobile phone in the case of conduction.

Acceptance sensitivity TIS(Total Isotropic Sensitivity): Reflects the situation of the mobile phone reception sensitivity index in the whole radiation sphere. It reflects the receiving sensitivity of the whole mobile phone, and is related to the conduction sensitivity of the mobile phone and the radiation performance of the antenna.

After passing the test, we can finally generate an EXL report on the obtained active parameters, so that customers can know at a glance whether the antenna performance is good or bad.

OTA testing capabilities:

1: Active part

Radiated Power (TRP)

Sensitivity Performance (TIS)

2: Passive part

Antenna gain test (Gain)

Antenna Interface Impedance Test (Input Impedance)

Antenna standing wave ratio/return loss test (VSWR/RL)

Antenna Pattern Test (Radiation Pattern)

Directionality (Directivity)

Beam Broadband/Front-to-Back Ratio (3Db BW/FB Ratio)

Cross Polarization Ratio/Isolation (Cross Polar/Isolation)

Supported wireless systems: active or passive testing of GSM,CDMA,WCDMA,TDSCDMA products; Passive testing of antennas such as Bluetooth, WIFI,DVB, etc;

Currently supported test specifications:

1:CTIA的OTA测试规范(Test Plan for Mobile Station Over the Air Performance V2.2.2)

2: OTA test specification of GCF (latest provisions of GCF CC V3.33)

3:3GPP/ETSI OTA antenna performance conformance testing (TS 34.114,TS25.144)

4: OTA Access Regulations Compulsory by China's Ministry of Industry and Information Technology in 2008 (YDT 1484-2006)

5: passive antenna test standard (Passive antenna test:IEEE149-1979)

TRP full name Total Radiated Power, that is, the total radiation power. Its meaning is the integral value of the radio frequency radiation power of the mobile phone on the three-dimensional sphere of space, which reflects the emission characteristics of the mobile phone in all directions. For example, it is like the sum of the light radiated by a light bulb in all directions. The brighter it is, the more energy it emits, and the darker it is, the less energy it emits. However, the radiated power has an upper limit. The mobile phone itself limits the maximum radiated power, and the output power of the RF module of any mobile phone will not exceed 2W(33dBm). The closer to this value, the better the signal emission ability, and the greater the radiation. This indicator is usually mutually restricted with the SAR indicator (an indicator that reflects the radiation absorbed by the human body). A qualified mobile phone must have both good emission capability and a lower SAR value.

China's standard YD1484-2006<> is a normative document for TRP measurement of mobile phones, which stipulates the minimum value of TRP. for GSM mobile phones, the 900 frequency band cannot be lower than 26dBm and the 1800 frequency band cannot be lower than 25dBm; For CDMA mobile phones, TRP cannot be lower than 20dBm, which is consistent with CTIA requirements in North America, compared with the European 3GPP standard, there are some differences in measurement methods.

At present, the widely accepted standard for measuring the radiation size of human body by wireless products is SAR (Specific Absorption Rate) value. The actual meaning of SAR is the size of radiation energy to human body, which refers to the ratio of radiation absorbed by human head or tissues of various parts of the body, and the unit is W/kg. The upper limit standard of SAR value stipulated by the International Commission on Non-Ionizing Radiation Protection (ICNIRP) and Europe is 2 W/kg, and the maximum SAR value stipulated by the Federal Communications Commission (FCC) of the United States is 1.6 W/kg. At present, the main standard of SAR in China is YD/T 1644.1 "Electromagnetic Irradiation of Human Body by Wireless Communication Equipment Used in Handheld and Body Wearing". Special attention should be paid here to the fact that the test value of SAR refers to the peak level, that is, the measured mobile phone is required to be measured and evaluated in the maximum power transmission mode!

Keywords: digital TV antenna, vehicle antenna, RF line/feeder, suction cup antenna