Research on Electromagnetic Measurement System Using Modulated Scattering Elements

由于天线的电磁辐射部分地被用户的人体观测到，因此需要准确、快速地测量移动的电话和PHS的天线的辐射效率。在本研究中，提出了一种使用并行调制技术的同时测量方法。研制了用于辐射效率测量的调制探头元件和测量系统，并已投入商用.提高系统精度。为了提高接收天线的增益和测量精度，研制了一种由偶极子和反射面组成的定向天线。通过调整本振信号的频率，降低了调制引起的噪声。此外，还进行了互耦分析，优化了探头阵列的位置.系统的宽带设计。设计了满足800 MHz-2.8GHz带宽要求的探头阵列.研制了三维天线辐射测量系统。利用该系统对天线的辐射效率进行了测量，并将测量结果与数值计算结果进行了比较。实验表明，该方法可以在16秒左右的时间内快速测量天线的辐射效率，测量精度令人满意.相位测量研究了如何测量电磁场的相位信息。然而，由于馈电电缆和每个探头的调制电路的延迟效应，调查发现相位测量困难。这部分的研究成为未来具有挑战性的工作。

It is required to measure the radiation efficiency of antennas of mobile phones and PHS accurately and rapidly, because the electromagnetic radiation from the antenna is partially observed by user's human body. In this research, a simultaneous measurement method using the parallel modulation technique has been proposed. The modulated probe element and the measurement system for radiation efficiency measurement have been developed for commercial use.1. Accuracy improvement of the system. A directive antenna composed of a dipole and a reflector has been developed to increase the gain of the receiving antennas and improve the measurement accuracy. The frequency of local signal has bee adjusted to decrease the noise caused by the modulation. Furthermore, the mutual coupling analysis has been carried out to optimize the location of the probe array.2. Broad bandwidth design of the system. The probe array has been designed to meet the requirement of the bandwidth of 800MHz-2.8GHz.3. A 3-D antenna radiation measurement system has also been developed. The radiation efficiency of antennas has been measured by the system and the measurement results have been compared with the numerical results. It has been demonstrated that radiation efficiency of antennas can be measured rapidly with a satisfactory accuracy in about 16 seconds.4. Phase measurement. It has been studied how to measure the phase information of the electromagnetic field. However, the investigation has found phase measurement difficult because of the delay effect of the feeding cables and modulation circuits of each probe. This part of research becomes the future work of challenge.