Directive Microstrip Antennas for Specific Below −2.45 GHz Applications

Microstrip printed antennas are the preferred choice in high data ratio modern communications, mainly at 2.45 GHz and above. In this paper, we propose two different approaches of microstrip printed antennas for lower frequency usage. In this sense, we present a printed microstrip Yagi-like antenna at 868 MHz and a printed dipole log-periodic antenna for wider band applications. We focus on the use of low-cost substrates, with a good performance at these frequencies, and giving antennas with useful sizes for such applications. For the analysis, we make use of standard experimental characterization combined with full-wave 3D-FDTD specifically developed simulations. In this way, the S11, radiation patterns, and gain/efficiency figures are given.