S-parameter Measurement of Differential Log-periodic Antennas for SKA Applications

For Square Kilometer Array (SKA) low-frequency aperture array, differentially-fed log-periodic antenna with all-metal structure is employed. In this paper, the reflection coefficient of differentially-fed log-periodic antennas with an additional metal measuring tool (MMT) is investigated. Specially, the measurement principle of the log-periodic antennas is analyzed by scattering matrix derivation. Based on the SKA log-periodic antenna (SKALA) elements, the structural influences of the MMT on antenna performance are numerically analyzed. Finally, the reliability and accuracy of the proposed measurement method is experimentally validated.