Investigation of Wideband and High-Gain Planar Millimeter-Wave Antennas

Millimeter-wave technology market grows rapidly in recent years. A forecast of this market will get to around US$ 2,302 Million in the year of 2023. Various products and applications related to millimeter wave technologies can be found. For example, security scanning systems at the airport and train stations screen potential dangerous objects hidden by suspects. Another image scanning technique at submillimeter-wave frequencies can be used for food safety and its quality control. In addition, intelligent anti-collision radars at 77 GHz assist the drive to prevent road traffic accidents. Gesture recognitions at 24 and 60 GHz bands can identify the motion of human body or hand precisely. Moreover, low-power millimeter-wave healthcare can relieve concomitant pains from the patient. Mostly important, wireless industries boot the millimeter-wave technologies to the 5G mobile services for high volume and fast speed communications. From the aforesaid examples, it is clearly seen that the millimeter-wave technologies are ready and continuously expanding into our daily life. Antennas are one of key components for realizing a reliable and robust millimeter-wave system. Conventional antenna solutions at millimeter-wave spectrum are cost-ineffective which may suffer from high fabrication and material costs. It would like to use micro machining and low temperature co-fired ceramic fabrications to realize the antenna body. Low-loss materials are also required to construct the antenna and the power distributed network to antenna arrays for high-gain and highefficiency radiation. It is therefore, the industry look for emerging antenna technologies that can provide low-cost and high-performance antenna solutions for different millimeter-wave systems. In this proposal, we will explore a number of new approaches of millimeter-wave antenna designs that will apply to existing and the coming millimeter-wave systems. The devoted antennas combined with multi-layered printed circuit boards and proposed special structures form a new wideband millimeter-wave antenna. We propose to apply the principles of Fabry-Perot resonator and open resonator to develop wideband, high-gain, beam-steering, and dual-polarized antennas which are low-cost, reliable and robust. In this proposal, three identified research objectives will be investigated. Firstly, a study of excitation for a quasi-ring reflector to generate multi-mode resonances in the Fabry-Perot resonator will be carried out. The solution by printing a set of metallic rings on different layers of high frequency laminates successfully shows a significant achievement in wider impedance bandwidth of the Fabry-Perot resonator antenna. Secondly, a beam steering antenna based on the structure of wideband Fabry-Perot resonator antenna will be investigated. Methods like multiple excitations with offset distances and re-distributions of refraction index on a metasurface are compared and applied to the antenna for obtaining beam steering characteristics. Finally, a dual-polarized high-gain millimeter-wave antenna will be demonstrated. The solution of orthogonally modified feeds to excite the invented antenna structure achieves excellent electrical characteristics such as high directivity, high port-to-port isolation, low cross polarization, low backlobe, and stable gain across the entire operating bandwidth for the proposed dual-polarized millimeter-wave antenna