Research on the relation between Printed Log-Periodic Antenna´s feed and bandwidth

According to the problems appeared during the design, simulation and actual making of Log-Periodic Antenna, this paper compared between different material of pad, calculation of parameters and method of simulation. Through selection, A Printed Log-Periodic Antenna was made using the material of TB-73. The antenna could be used in the channel of 700 MHz to 3 GHz from the results of actual measuring, the average of Gain was better then 9 dB, and the VSWR was less than 1.2 from 700 MHz to 2 GHz. Adding covering which was made of PEI and changing the feed structure were also measured and analyzed. From the results, the operating frequency became narrow after adding covering, and the bandwidth in high frequency points dropped 200 MHz. With the change of feeder, VSWR was higher than 2 in high frequency points and reduce to less than 1.2 in low frequency. This paper has some guidance ideas to the design of LPDA.