Size-reduced printed log periodic dipole antenna with single first order semi-circle iteration and feed point patches

Abstract

This paper presents the miniaturization and improvement of a printed log periodic dipole antenna (LPDA) by using patches at the feeding point and single first order semicircles. After the design of a conventional printed LPDA on FR4 substrate to cover L-band is performed, patches having 12 mm × 5 mm dimensions are placed to the feed point of the antenna. Although this modification gives same antenna size, it brings considerable increase in the return-loss bandwidth up to 2.25 GHz and higher gain values up to 2 GHz at the expense of decrease in gain at about 2.4 GHz. Afterwards, in order to reduce the total size of the antenna, single semicircles are substituted into the dipole arms, which results in 14% lateral size reduction. Besides, the bandwidth is further improved between 0.9 GHz and 2.4 GHz with better return loss performance, higher gain at 2.4 GHz and lower gain variation.