Design of a compact miniaturized probe-fed patch antenna using electromagnetic bandgap structures

Patch antennas are commonly used in wireless applications due to their low profile and ease of fabrication. These antennas can be relatively large in mobile and WLAN frequency bands, and methods for miniaturization should be employed in order to make them viable for compact form factors. One of these techniques involves loading the antenna with an electromagnetic bandgap (EBG) structure. EBG structures are typically operated in their bandgap region in order to suppress unwanted surface waves or reduce the inter-element substrate coupling in multi-antenna systems [1–3]. An EBG structure also supports slow-wave propagation in which smaller effective wavelength compared to those in freespace and dielectric can be achieved. Thus, the area occupied by a patch antenna can be significantly reduced by simply integrating it above an EBG substrate [4,5]. In this paper, a miniaturized probe-fed patch antenna backed by a mushroom-type EBG substrate is designed that achieves 66.83% area reduction. Different EBG unit cell sizes are simulated in order to determine the proper slow-wave wavelength that yields the smallest width and length for the patch without compromising its radiation characteristics. The performance of the designed miniaturized antenna is also compared with that of a conventional one. Finally, the coupling between two miniaturized antennas is evaluated in the E- and H-plane arrangements in order to observe the impact of miniaturization EBG on reducing the mutual coupling.