Design Approach for Pattern-Reconfigurable Patch Antenna Without Extra Feeding Networks

In this communication, an efficient approach with multiple loading techniques is proposed to design a low profile, single-fed, pattern reconfigurable patch antenna with broadside and dual-beam radiation patterns. Initially, a transmission-line model is developed to theoretically investigate the resonant frequency of a rectangular patch antenna with radiation efficiency (
$\eta _{r}$
) into consideration as well. It is revealed that the frequency overlap in the two states without significantly sacrificing
$\eta _{r}$
can be achieved by properly loading shorting pins and open-ended stubs. Besides, the two center-loaded elements, i.e., a shunt capacitor and a series inductor, are also studied for demonstration of their unique effects on impedance matching for both states or operating modes. Then, a design guideline is summarized based on the theoretical analysis. Following the developed guideline, two examples working at the same operating frequency of 2.45 GHz are designed, fabricated, and tested. Measured gains of 9.6 (8.7) and 5.6 (5.3 dBi) of antenna example A (example B) are obtained for broadside and dual-beam modes, respectively. The measured and simulated results are observed in good agreement, thereby demonstrating the validity of the proposed scheme. The merits of low profile, high gain, and no need of extra feeding networks make the proposed antennas good candidates for modern communication systems.