Study on Broadband Phased Array Antenna Using Log-Periodic Elements

摘要

In this thesis, the quantitative analysis of the bandwidth of the phased array is presented for the realization of the broadband phased array antenna. The array factor of the 5x5 array is first examined in order to understand the array characteristics without the mutual coupling of antenna elements. As broadband antenna elements, two log-periodic antennas are analyzed numerically and empirically. One is the log-periodic dipole array (LPDA) antenna which has 22 dipole elements and a 10:1 bandwidth. The other is the log-periodic printed dipole array (LPPDA) antenna which has 14 dipole elements and about 3:1 bandwidth. Two element LPDA phased array is investigated in terms of the mutual coupling and the actual gain. The scan performance is evaluated to find the appropriate bandwidth of the antenna element for the broadband phased array. Three models of the 5x5 LPDA array are analyzed numerically and the scan performance of each model is evaluated by the criteria of the actual gain, the sidelobe level (SLL) and the scan angle deviation (SAD). The feasible bandwidth examples of the 5x5 LPDA array are compared with the correspondent array factor models. Conclusively, it is worthwhile to note that the broadband phased array can be possible for the specific applications.