Antenna Measurement System Using Optical Fiber Link and Vertical Articulated Robot

We have developed near field antenna measurement system using optical fiber link and vertical articulated robot for 5G antenna measurement. Our developed optical fiber link system consists of 850 nm multi-mode VCSEL (Vertical cavity surface emitting laser diode) and PDTIA (Photo diode with transimpedance amplifier). Our optical fiber link system can use for microwave measurement from 100 MHz to 40 GHz with 60 dB dynamic range. Further, we have developed a compact type antenna near field measurement system using vertical articulated robot that has 6-axis 1 m length arm that can hold 4 WR-28 open ended waveguide probe. In this paper, we show a measured near field radiation pattern for WR-28 standard gain horn antenna using OEWG and our optical fiber ling system up to 40 GHz.

I. Introduction

Fifth generation mobile communication system (5G) uses 3.7, 4.5 and 28 GHz Frequency band [1]. For measuring an antenna radiation pattern and gain for high frequency, we usually uses near field antenna measurement[2]. NIST have already developed a vertical articulated robot system for millimeter wave antenna [3] [4]. These antenna measurement system usually uses coaxial cables. Coaxial cable has some problems for 5G frequency band, such as the large attenuation of signals in the cables, reflection waves from the cable and the difficulty of their handling. For this reason, we have newly developed a microwave receiving or a microwave transmitting system using a 850 nm multimode vertical-cavity surface emitting laser diode (VCSEL), multimode optical fiber and a photo diode with trans-impedance amplifier (PDTIA). Further, we have developed multi probe type optical fiber link antenna near field measurement system using 1m arm vertical articulated robot [5] that can hold 4 OEWGs connect with VCSEL.