Investigations On Millimeter-Wave Reflectarray And Lens Antennas

Microwave and millimeter wave (MMW) reflectarray and lens antennas play important roles in the fields of communication, radar, astronomy and imaging. The investigations on reflectarray and lens antennas with high gain, high directivity, low profile and easily integrated with planar circuits have important significance for these applications. Conventional reflector, lens and their primary source are fabricated with 3D structures. Therefore, the integration of high gain (as high as 30dBi) antenna with planar circuits has become a big issue in the recent years. On the other hand, investigations on the separately passive components with low loss, and integrating all these components into one system with high efficiency is another challenge. Based on the technology of Substrate Integrated Waveguide (SIW) and Substrate Integrated Coaxial Line (SICL) technology, this dissertation has investigated a series of compact planar source antennas, transitions and filters. By integrated design of feed antenna with the reflectarray/lens, the planar source-fed reflectarray/lens antenna is achieved with minimum profile, high gain and high radiation efficiency. The main contributions of this dissertation are organized as follows:Chapter one proposed three types of primary source antennas fabricated by Printed Circuit Board (PCB) and Micro Electro Mechanical System (MEMS) technology, which includes a 2×2 SIW slot array antenna, a SIW backed-cavity fed stacked patch antenna, and a planar horn antenna for THz applications. The work principles, design process, and simulation models of the primary antennas are presented in detail. The measurements and simulations testify the design methods. Part of the work in this chapter has been published in IEEE Trans. on AP.Chapter two introduces the integrated design of planar reflectarray. Firstly, the operation principle of the reflectarray based on Phase Shifting Surface (PSS) is presented, and the effect of focal length and diameter ratio (f/D) on gain is analyzed. Then three types of folded reflectarray antenna with high gain are proposed and designed. By employing pyramid horns as the feed source of the antenna, a folded reflectarray with high gain and broad bandwidth is achieved; After that, the pyramid horn is replaced by a 2×2 SIW slot array antenna as the feed source, which makes the whole antenna system much lower profile and easily integrated with planar circuit. several methods are developed to fulfill the integrated design of the feed and reflectarray, the gain and efficiency of the antenna system are highly improved. The measurements agree well with the simulations which testify the design method; A configuration to realize THz folded reflectarray antenna with planar source is also proposed in this dissertation. Both the planar feed and reflectarray are fabricated by MEMS processing, which makes the whole antenna system feature good fabrication accuracy and consistency. Simulations shows good gain and radiation performance, which testifies the effectivity of this configuration. Some designs in this chapter have been published in Int. Symp. Antennas Propag (ISAP) and achieved the Best Paper Award of ISAP’2013.Chapter three introduces the integrated design of planar lens antennas. The operation principle of the planar lens antenna and its scanning properties are presented. A thin planar lens with double metal surface is proposed for the 28GHz massive (Multiple-Input Multiple-Output) MIMO communication applications. By loading seven planar source elements behind the lens, a beamforming antenna with high gain, broadband and wide angle coverage are achieved. The measurements agree well with the simulations which testifys the design method; Also, a perforated dielectric substrate lens is designed to load the feed horn for 45GHz long distance communications. The gain and directivity of the primary horn is significantly improved without any increased room of the primary horn. Some designs in this chapter are submitted to IEEE Trans. on AP.Chapter four investigated a radar retrodirective antenna with polarization rotation properties. Retrodirective antenna is widely used in radar, satellite, wireless power transmission applications due to its wide angle coverage and enhanced Radar Cross Section (RCS). In order to improve the polarization separation of the systems, a retrodirective antenna with polarization rotation properties is preferred. However, the polarization rotation properties is not existing naturally in any metal surface. Thus we proposed the structure of polarized grid-polarization rotation reflectarray to realize the functions of retrodirective beam as well as twisting the polarization. This dissertation presents the operation principle and design process of the proposed antenna in detail. An experiment at 25.5GHz for vehicle radar application is implemented, which testifies the good performance of the antenna. The work in this chapter is submitted to IEEE Trans. on AP.Chapter five investigated passive components based on SICL technology. This dissertation presents the multilayer structure, field distributions and propagation diagram of SICL. Then a 0-20GHz microstrip to SICL transition, a 30-50GHz CPW to SICL transition and a 75-110GHz waveguide to SICL transition are proposed and investigated respectively, which can be a design guideline for SICL transition over 0-100GHz; The half wavelength SICL resonator is proposed and analyzed. The single, dual, and triple bandpass filters based on the combinations of bandpass and bandstop SICL resonators are proposed. All the measurement results shows the SICL structure features compact size as well as good bandwidth performance. Some works in this chapter have been published in Microw. Optical Techn. Lett. and IEEE APMC’2014.