Gain and efficiency enhancement of compact and miniaturised microstrip antennas using multi-layered laminated conductors

When microstrip antennas are miniaturised, because of high ohmic losses, their gain and efficiency drop significantly. In this study, a new technique is presented to improve these two important parameters of such antennas, where multiple laminated conductors are used to form the conducting patch. The technique essentially reduces the ohmic losses, and consequently improves the gain and efficiency. At first, a planar conductor is studied to show that using multiple laminated conductors, instead of a single conductor of the same thickness, losses can be reduced. The same technique is then used in several miniaturised microstrip antennas, in order to reduce their ohmic losses. It is shown that this process enhances the gain and efficiency of these antennas progressively, by increasing the number of layers in the lamination. Simulation studies on two miniaturised antennas have provided about 1.5 and 2.4 dB improvement in the gain, and from 30 to 40.7 improvement in the efficiency. Experimental investigations are also conducted and confirmed the simulated results. For a microstrip square ring antenna, a measured gain enhancement of 2.16 dB at 2.2 GHz is obtained, by laminating only the ring with four conducting layers.