Design and implementation of miniaturized antennas for wireless communications

Miniaturization of planar microstrip antennas have been investigated. Different techniques have been applied to design miniaturized antennas serving for wireless communication systems. These techniques were inspired from understanding the common features of planar antennas and the requirements of these antennas to be working at certain frequencies like Wireless Local Area Network (WLAN) antennas or even covering wider range of frequencies such as Ultra-Wide Band (UWB) antennas, meanwhile keeping its properties almost unchanged. In this work, the design techniques of these antennas were emphasized, and how is it possible to have smaller size with same characteristics. The essential idea is to enable excitation current to follow the same path length as required in the full size antenna within smaller size in the miniaturized structure. Corrugating and meandering were used as two main techniques that fulfil the requirements. Another technique of eliminating the least excited areas of the planar antennas was also introduced. The location of these areas has been determined by simulating the surface current distribution of the full size antenna before miniaturization process. All of the designed antennas have been simulated by CST Microwave Studio 2014, and they have been fabricated on FR4 PCB boards then tested via practical measurements by using Rohde & Schwarz® ZVL13 Vector Network Analyzer. Simulation and measured results shown a good agreement, and confirming the validation of the techniques being used. In addition, the suggested techniques succeeded to miniaturize the overall size of Planar Strip-Shaped Monopole Antenna (PSSMA) serving WLAN applications, by (10.7%) of the original antenna size for Corrugated PSSMA and (14.28%) for Meandered PSSMA. Also enables miniaturization of the overall size of Planar Circular Monopole Antenna (PCMA) by (11.8%) of the original antenna size for Planar Crescent-Shaped Monopole Antenna (PCSMA), and (42.6%) for Corrugated PCMA while stile covering the UWB frequency range. Although the reduction in Corrugated PCMA is huge but results shown that its gain stile higher than 2 dB which is comparable to the traditional half-wave dipole gain.