Design of a High-gain Cavity-backed Slot Antenna with Mushroom Cells and Bent Ground Walls

High gain antennas have many applications in wireless communication systems as they produce focused and narrow beamwidth, which allow for more precise targeting of the signal. Therefore, various gain enhancement techniques for antennas have been studied in the past decades [1–21]. Specifically there are three important methods to achieve this purpose: (1) Using antenna array, (2) Adding superstrate, and (3) Using intrinsically high gain antenna. For a very high gain, the array should contain a lot of elements if the gain of each element is not high, which not only increases the size of the array, but also decreases the efficiency of it [1–3]. Superstrates are also used for gain enhancement [4–7]. However, these antenna structures are either complicated or having thick profiles. In addition, a large superstrate size is usually required. Antennas like horn, YagiUda and cavity backed slot can produce high gain. The horn is usually bulky, therefore an integrated horn antenna with fairly low profile at 60GHz was presented in [8] that produces 14.4 dB gain. However, the antenna size is still large (5.2λ× 4λ). The Yagi-Uda antenna was