Beamforming algorithm and modification of 60-GHz spherical radiated array antenna

Abstract

As mobile devices, such as smartphones and tablet PCs, occupy an increasing proportion in personal life, various functions and technologies are being integrated into mobile devices. In particular, recently, attention has been focused on applications using virtual reality such as VR HMD and AR Glass. High-speed wireless communication is essential for the utilization of mobile devices that process high-capacity data. To this end, since high-speed data communication is possible with a wide bandwidth of 9 GHz and the size of the system can be reduced with a high frequency, various attempts are being made to apply wireless communication using a 60 GHz band to mobile systems. In particular, it is necessary to research a 60 GHz beamforming system for transmission in a desired direction and for use in a non-line-of-sight communication environment. Among them, research on array antenna technology has many difficulties due to the problem of deterioration in efficiency and coverage due to the high frequency and shortened wavelength of the millimeter wave band. Therefore, this paper proposes and verifies an optimal array antenna structure for an antenna-in-package that emits a beam with a spherical coverage and a beamforming algorithm suitable for the mobile communication environment of the 60 GHz band.This thesis consists of a total of 4 chapters. Chapter 2 proposes a 60 GHz beamforming algorithm that finds the optimal beam for transmission and reception using an antenna-in-package. The beamforming algorithm is largely composed of an “initial beam selection” part and a “beam tracking” part. The “Initial Beam Selection” part is the process of finding the initial beam when AR Glass is turned on. The “initial beam selection” part proceeds in the order of the “array antenna selection” process to find a pair between the transmit and receive array antennas, the “receive beam selection” process, and the “transmit beam selection” process. The “beam tracking” part is the process of tracking the beam according to the user's movement while using AR Glass. The “beam tracking” part consists of a “pre-inspection” process that checks whether beams at the same location meet the requirements over time, and a “nearest Find the beam” process in order. Chapter 3 proposes a new array antenna to improve the spherical radiation pattern of the antenna-in-package introduced in Chapter 2. In the previous antenna-in-package, the beam radiation pattern is generally elliptical, and there is a “weak spot” problem in which the gain is formed low in the portion where different array antennas are stitched together. Therefore, in this paper, the center axis of the dipole array antenna and the center axis of the patch array antenna are alternately arranged to create an improvement effect that offsets the “weak spot”. In addition, by adjusting the distance between the elements of the patch array antenna, the overall elliptical beam radiation pattern was modified to be nearly spherical as a whole. Finally, Section 4 summarizes and concludes the thesis.