Passive Testing of Electrically Small Antennas in Electronic Systems

In this paper, a measurement scheme, which eliminates the interference of the common mode current, for electrically small antennas is proposed. Firstly, the causes and effects of common mode currents appearing in passive testing are analyzed. Then, the influence of different outlet points of coaxial cable on the passive testing of antenna is studied experimentally and numerically. According to the distribution of the common mode currents on the ground plane when the coaxial cable feeds the antenna, the minimum current point is selected as the outlet point of the coaxial cable to reduce the influence of common mode current. Additionally, the influence of the coaxial cable’s arrangement and the soldering area between coaxial cable and ground plane on the antenna under test is studied. Finally, considering the output point, arrangement and soldering area of the coaxial cable, a measurement scheme to improve the passive measurement accuracy of the electrically small antenna is proposed.