Department of Electronics and Telecommunications, Constanta Maritime University, 900663 Constanta, Romania.
Doctoral School of Electronics, Telecommunications and Information Technology, University Politehnica of Bucharest, 061071 Bucharest, Romania.
Sensors (Basel). 2020 Jul 13;20(14):3893. doi: 10.3390/s20143893.
Common mode currents on antenna feeders usually occur when feeding a symmetric radiator through an asymmetric line, or when the ground plane is electrically small. Such currents may have magnitudes comparable to the feed currents and therefore have a major impact on the total radiated field. For antenna radiation measurements, both assessment and reduction of the common mode currents on antenna feeders are crucial. Techniques to discriminate antenna and feeder radiation are mainly needed for design and optimization purposes. Antenna gain measurements in a multipath site can be performed by using the distance averaging method. In this paper, we show that the distance averaging technique can be applied to reduce the effect of common mode currents for measuring the field radiated by symmetrical antennas. Two measuring configurations are proposed depending on the number of symmetry degrees of the antenna under test, and a differential approach for extracting the field created by the common mode currents was also developed. The experimental validation was performed by measuring a simple wire dipole and a log-periodic dipole array (LPDA) with a small square loop as a probe, both on the feeder side and on the feeder free side.
当通过非对称线馈送电对称辐射器时，或者当接地平面尺寸较小时，通常会在天线馈线中出现共模电流。这些电流的幅度可能与馈电电流相当，因此会对总辐射场产生重大影响。对于天线辐射测量，评估和减少天线馈线中的共模电流至关重要。主要需要用于设计和优化目的的天线和馈线辐射的区分技术。在多径场中进行天线增益测量时，可以使用距离平均法来实现。在本文中，我们表明，距离平均技术可应用于减少测量对称天线辐射场时共模电流的影响。根据被测天线的对称度数，提出了两种测量配置，并开发了一种用于提取共模电流产生的场的差分方法。通过在馈线侧和馈线自由侧上使用小方形环作为探头测量简单的线偶极子和对数周期偶极子阵列 (LPDA) ，对其进行了实验验证。
