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4 test methods for 5G base station antenna OTA
Source:Originally | Author:Calio Huang of C&T RF Antennas Inc | Publish time: 2019-05-03 | 186 Views | Share:

The Abstract

The research method of 5G base station antenna OTA test research on the large-scale MIMO active antenna OTA test method of the 5G base station. In this paper, the necessity of an integrated OTA test for 5G base station antenna is analyzed. Different OTA test schemes such as far field, compact field, multi-probe near field and single probe near field are introduced. The advantages and disadvantages of each test scheme are tested through the actual test. The comparative analysis points out the problems faced by the current 5G base station antenna OTA test and proposes a solution.

[Keywords] 5G; base station antenna; OTA test

1. Introduction

5G mobile communication technology can meet people's needs for fast-growing mobile communication services such as high speed, large capacity, high reliability, and low latency. The large-scale MIMO active antenna technology as one of the key technologies of 5G mobile communication can greatly improve the spectrum utilization efficiency through spatial multiplexing, and can greatly improve the communication system capacity by combining the new coding technology.  And the communication rate. Therefore, the large-scale MIMO active antenna technology is a commonly used technology in 5G mobile communication base stations, but it is followed by the problem of how to test 5G base station antennas.

For a traditional base station, the antenna and the RRU (Radio Remote Unite) are separated from each other. They are connected by RF cables, which are relatively independent and have no performance impact. Their respective performances can be independently tested. Carry out an inspection. The radiation performance test of the antenna can be done in the microwave darkroom through far-field or near-field methods. The far-field or near-field test of the passive antenna is a mature test method widely used in testing antenna performance. The RRU's RF specifications can be measured in the laboratory by conduction.

Referring to the traditional base station test mode, it is easy to propose a scheme of splitting the active antenna system into a passive antenna array and an RRU to perform antenna radiation performance test and RF conduction test respectively. In fact, according to laboratory testing experience, the beamforming pattern measured by "passive antenna array + power division network + signal source" is integrated with the 5G base station active antenna integrated OTA (Over the Air) test. The results are not consistent. The RF performance conduction test results of the "RRU+ Coupling Board" also differ from the RF radiation indicators measured by the integrated OTA. The reason is that for a 5G base station antenna, the antenna is integrated with the RRU. On the one hand, interference factors such as electromagnetic coupling and active standing wave cannot be completely eliminated; on the other hand, the calibration and amplitude and phase weighting of the active antenna pass through the respective RF channels. The combination of a series of active devices is quite different from the way in which the passive antenna array performs amplitude-weighting through a passive power division network. Therefore, for a 5G base station using massive MIMO active antenna technology, the integrated OTA test mode can effectively reflect its performance indicators. Especially in the millimeter wave band, the frequency band is higher, the device size is smaller, the electromagnetic interference problem is more prominent, and the split test will be very difficult, and only the integrated OTA test solution can be adopted.