Antennas are the essential building parts of the microwave and millimeter-wave wireless systems. With the development of emerging wireless system, for example, the fifth generation (5G) communication, high-precision position and high-resolution imaging，it raises an unprecedented interest on high rate of data transmission. On the other hand, millimeter-wave band has relatively sufficient spectrum resource compared with lower microwave frquency band. Therefore, it is of great significance to investigate and develop substrate integrated antennas and arrays with low cost and high performance at millimeter-wave band. Substrate integrated waveguide (SIW) has self-shielding architecture, low loss, low cost and planar integration ability. Base on these, this dissertation focuses on the investigations of millimeter-wave subatrate integrated antennas and arrays, including 94-GHz differentially-fed low-sidelobe array antenna, 60-GHz differentially-fed dual-polarization array antenna, polarization-adjustable planar integrated antenna array, wideband three-dimensional linearly and circularly polarized microstrip array antenna, three-dimensional subatrate integrated monopulse array antenna, and W-band multi-beam array antenna, etc. The dissertation is organized as follows:
The introduction starts with a brief review of the millimeter-wave system applications and the associated frequency spectrum allocation. Then, the research status of topic on SIW technology and related antenna and array is introduced. Finally, the research contents and objectives in the dissertation are described.
Chapter one designs and implements two differential-fed substrate integrated array antennas, which present the co-design perspective to directly integrate antenna with the differential circuit or chip nonuse of any Balun transition for saving loss and volume of whole system. In the 94-GHz low-sidelobe array antenna, patches are series-connected by electromagnetically-coupled coplanar SIW, their unequal widths are tapered for E-plane low sidelobe. Low-sidelobe H-pane radiation pattern is achieved by multi-stage SIW unequal power dividers for tapered aperture distribution. In the 60-GHz dual-polarization antenna, coupled cavity and patch yield dual-resonance bandwidth enhancement, stacked cavity-backed patch subarray improve the antenna gain. Differential excitation provides antenna low cross-polarization level and high port-to-port isolation. All the antenna arrays are fabricated by the printed circuit board process. The simulated and measured results prove the feasibility of design.
Chapter two presents a slot-loaded high-order-mode microstrip patch antenna driven by SIW for millimeter-wave multi-polarization applications. The radiated patch resonates at high-order mode, which causes an enlarged aperture and offer the space for the layout of orthogonal dual-polarization SIWs. The radiation pattern is improved by means of loaded slots on the patch. Dual-resonance impedance matching is achieved from the patch and SIW slot. A Ka-band 2x2 planar integrated antenna array with single-layer SIW feeder is designed to feature adjustable polarizations. Different polarization status, including vertical and horizontal linear, right handed and left handed circular polarizations, can be adjustable depending on the configuration of input signals. Morover, orthogonal SIW feedings in two-layer scheme is developed, which would get rid of the cross of two-polarization signals, provide a more compact, simple and flexible array topology. A 4x4 array antenna is implemented based on multi-layer SIW feeding network, which achieves dual polarizations with unidirectional radiation and high port-to-port isolation. All the antennas are fabricated by the printed circuit board process, experiment results demonstrate the correctness of dedign. Some works of this chapter were published in IEEE Trans. on Antennas and Propagation.
Chapter three presents the wideband microstrip array antenna driven by SIW in three-dimensional architecture for linear and circular polarizations. The antenna arrays incorporates of the vertical or 3-D SIW feeding and horizontal radiation block. This LEGO style explores a 3-D substrate integrated antenna and array, and offering a flexible strategy for spatial power distribution. Compared with the 3-D metal-waveguide structure, SIW counterpart has low cost, light weight, and flexible topology. The SIW cavity vertically-coupled patch antenna with linear polarization exhibits numerous advantages, including wide bandwidth, stable gain, low cross polarization and symmetrical radiation pattern. For the circularly polarized 2x2 H-shape patch array antenna, improved axial ratio bandwidth is achieved from the desired sequential-rotation excitation offered by a 3-D SIW feeder within the limited radiation aperture. 3-D substrate integrated antenna arrays are fabricated by printed circuit board process. The consistent results in simulation and measurement prove the feasibility of design. Finally, possible applications of these 3-D integrated patch antennas are discussed and analyzed. Works of this chapter were published in IEEE Antennas and wireless Propagation Letters.
Chapter four designs and implements some 3-D substrate integrated linearly- and circularly-polarized monopulse array antennas based on microstrip antenna and associated beam-forming network. Antenna arrays are composed of horizontal patch array and vertical or 3-D SIW comparator. Two types of comparator, 180°directional coupler and substrate integrated magic-T, are used for one-dimensional monopulse antenna array. Different radiated patches are used for generate linear and circular polarizations, respectively. The results indicate the monopulse array antennas relied on magic-T achieve better port-to-port isolation than coupler-based counterparts. In the two-dimensional circular-polarization monopulse array antenna, two-dimensional monopulse comparator is formed by multiple magic-Ts, vertical transition, and T-junction. All the antenna arrays are made by printed circuit board process with 3-D cost- and weight-effective architecture. Good agreement between two cases of results in simulation and measurement support the correctness of design.
Chapter five provides the deisgn and implemention of W-band fixed- and multi-beam subatrate integrated series-connected patch array antennas. Series-fed technology could significantly decrease the loss and size of feeding network. The microstrip series-connected patches antenna is aperture-coupled by the slot loaded on the top surface of SIW, which offers narrowed beamwidth in E-plane and improved antenna gain. This special configuration could decrease the density of SIW and create favorable conditions for the compact structure of SIW-based antenna and array. Furthermore, the introduction of SIW feeding provides more flexible array topology and gets access to the integration with low-loss SIW beam-forming network for beam-scaning application at milllimeter-wave band. With this patch array and SIW network, W-band fixed- and multi-beam array antenna are designed and implemented. The antenna arrays are developed relying on low-cost printed circuit board technology, characterizing of easy integration, planar profile and small weight. Some works of this chapter were published in 2017 11th European Conference on Antennas and Propagation (EUCAP).