A multibeam beam-forming network (BFN) for generating 2-D multibeam array antenna (MAA) is proposed using single-layer substrate integrated waveguide (SIW) technology. Firstly, a new topology for ...building <inline-formula> <tex-math notation="LaTeX">16\times 16 </tex-math></inline-formula> BFNs is proposed, which successfully transforms the traditional topology from a 3-D configuration to a 2-D (or uniplanar) one. Two major challenges are tackled during this transformation, namely, the planarization of basic components and the reduction of excessive intersections between multiple paths. To this end, a novel design of eight-port hybrid couplers, as critical components of this BFN, is developed to transform a 3-D to a 2-D structure. Furthermore, a new design of eight-port crossover, which can address four path intersections simultaneously, is proposed to reduce the total number of path intersections from 16 to only 4. The proposed topology for <inline-formula> <tex-math notation="LaTeX">16\,\times \,16 </tex-math></inline-formula> BFNs allows all the basic components, including eight-port hybrid couplers, eight-port crossovers, and phase shifters, to be placed within a single-layer configuration. Fed by the proposed uniplanar <inline-formula> <tex-math notation="LaTeX">16\times 16 </tex-math></inline-formula> BFN, a 2-D MAA with 16 (<inline-formula> <tex-math notation="LaTeX">4\,\times \,4 </tex-math></inline-formula>) beams, which is capable of switching the beams in both elevation and azimuth directions, is realized. Compared with the previous 2-D Butler matrix (BM) designs using multilayer technology, it is for the first time that a uniplanar design of <inline-formula> <tex-math notation="LaTeX">16\times16 </tex-math></inline-formula> BFN is proposed and realized, which significantly simplifies the design and fabrication complexity.
A wideband dual-layer Huygens' unit cell based on offset electric dipole pair (OEDP) is proposed. Different from traditional designs with a combination of electric and magnetic polarizabilities, the ...proposed Huygens' unit cell exclusively employs electric polarizabilities. By doing so, it practically avoids the unbalanced resonant frequencies between the two polarizabilities, thereby achieving wideband transmission. Based on the proposed unit cell, a wideband and high-gain multibeam array antenna is developed. First, a Rotman lens is designed by using a substrate-integrated waveguide (SIW) technology. Then a parallel-fed slot antenna array is connected to the Rotman lens to generate multiple beams. Without using a series-fed slot antenna array, the multibeam array antenna based on Rotman lens can operate within a relatively wide bandwidth (28-32 GHz). Second, a wideband dual-layer Huygens' metasurface is developed that serves as a superstrate of the multibeam array antenna for increasing the antenna gain further. A wideband and high-gain multibeam array antenna is finally realized, which is comprised of a Rotman lens, a parallel-fed slot antenna array, and a Huygens' metasurface. To verify the performance of this design, a prototype is fabricated and its measured results are compared to the simulated counterparts.
Reactive polymer blending is basically a flow/mixing‐driven process of interfacial generation, interfacial reaction for copolymer formation, and morphology development. This work shows two ...antagonistic effects of flow/mixing on this process: while flow/mixing promotes copolymer formation by creating interfaces and enhancing collisions between reactive groups at the interfaces, excessive flow/mixing may pull the in situ formed copolymer out of the interfaces to one of the two polymer components of the blend, especially when the copolymer becomes highly asymmetrical. As such, the copolymer may lose its compatibilization efficiency. The mixing‐driven copolymer pull‐out from the interfaces is a catastrophic process (less than a minute), despite the high viscosity of the polymer blend. It depends on the molecular architecture of the reactive compatibilizer, polymer blend composition, flow/mixing intensity, and annealing. These findings are obtained using the concept of reactive compatibilizer‐tracer and a model reactive polymer blend.
A novel three-layer substrate-integrated waveguide (SIW) <inline-formula> <tex-math notation="LaTeX">9\times9 </tex-math></inline-formula> Butler matrix (BM) that can produce a broadside beam and ...wide-angle coverage is presented in this article. Unlike the traditional <inline-formula> <tex-math notation="LaTeX">8\times8 </tex-math></inline-formula> BM, the proposed BM is realized by cascading three-way couplers. Connecting to the radiation structure and feeding the center input port, a phase difference of 0° is observed and a broadside beam can be produced. When exciting the side input ports, a maximum phase difference of ±160° is obtained and wide-angle side beams are generated. The operation principle and design development of the <inline-formula> <tex-math notation="LaTeX">9\times9 </tex-math></inline-formula> BM are illustrated in detail to determine the topology and the phase shifters. With the desired phase differences and amplitude distributions, a three-layer topology of the <inline-formula> <tex-math notation="LaTeX">9\times9 </tex-math></inline-formula> BM is developed to reduce the footprint and improve the compactness, which is subsequently realized in SIW technology. To realize wide-angle coverage, a new endfire metasurface antenna derived from the traditional Vivaldi antenna is proposed, which achieves a fractional 10-dB impedance bandwidth of 72% and a half-power beamwidth (HPBW) of 128° at 28 GHz. By integrating the three-layer SIW <inline-formula> <tex-math notation="LaTeX">9\times9 </tex-math></inline-formula> BM with an endfire metasurface antenna array, a wide-angle endfire multibeam metasurface antenna is obtained, which achieves a wide HPBW coverage of ±113° and a maximum gain of 12.1 dBi. The topology of an extended single-layer <inline-formula> <tex-math notation="LaTeX">18\times18 </tex-math></inline-formula> BM based on the designed <inline-formula> <tex-math notation="LaTeX">9\times9 </tex-math></inline-formula> BM is presented, and multilayer solutions are adopted to demonstrate the possibility of realizing higher order BMs.
A wideband metasurface antenna operating at millimeter-wave spectrum in substrate-integrated waveguide (SIW) technology is proposed. Coupled by a slot etched on an SIW section, the proposed ...metasurface antenna achieves a wide 10 dB impedance bandwidth in simulation from 19.2 to 42.4 GHz, indicating a fractional bandwidth of 75%. The development of the proposed metasurface antenna can be divided into four stages, i.e., a slot antenna, dielectric loading, adding covered metasurface, and connecting to a transition. The input impedance and the resonance of these stages are elaborated in detail to explain the working mechanism. Parametric study is carried out to inspect into the design process. By analyzing the <inline-formula> <tex-math notation="LaTeX">E </tex-math></inline-formula>-field distributions, the proposed metasurface antenna is characterized by TM 10 mode, antiphase TM 20 mode, and TM 30 mode. Compared with other similar designs in the open literatures, the proposed metasurface antenna displays a widest impedance bandwidth. The dimension of the proposed metasurface antenna is <inline-formula> <tex-math notation="LaTeX">0.80\,\,\lambda _{0} \times 0.72\,\,\lambda _{0} \times 0.24\,\,\lambda _{0} </tex-math></inline-formula>, where <inline-formula> <tex-math notation="LaTeX">\lambda _{0} </tex-math></inline-formula> is the free-space wavelength at 30 GHz. The maximum gain within the interested frequency spectrum is 7.0 dBi.
A wide-angle scanning circularly polarized (CP) antenna array based on a novel polarizer is proposed. The working mechanism is that the linear polarization (LP) substrate integrated waveguide (SIW) ...slot antenna array can be converted into CP antenna array through the proposed hybrid polarizer. Specifically, the proposed hybrid polarizer consists of a dipole array polarizer with <inline-formula> <tex-math notation="LaTeX">6\times </tex-math></inline-formula> 6 elements and a metasurface polarizer with <inline-formula> <tex-math notation="LaTeX">19\times19 </tex-math></inline-formula> elements. The metasurface polarizer can realize the LP-CP conversion of the beams with a scanning angle range (−55°, 55°) and the dipole array polarizer can realize LP-CP conversion of beams with scanning angle ranges (−60°, −40°) and (40°, 60°) through reasonable design. Based on the complementary characteristics of the metasurface polarizer and dipole array polarizer for different scanning angles, the proposed hybrid polarizer gives the designed CP antenna array have good AR characteristics in the scanning angle range (−70°, 70°). Then, a <inline-formula> <tex-math notation="LaTeX">6\times </tex-math></inline-formula> 6 Butler matrix is designed to feed the proposed wide-angle scanning CP antenna array. Finally, a prototype of the wide-angle scanning CP antenna array is fabricated. The test results show that the AR of the proposed wide-angle scanning CP antenna array is less than 3 dB, the maximum scanning angle is −60°, and the maximum gain is more than 16.5 dBi in the operating frequency range 27.9-28.4 GHz.
A parallel-plate Luneburg lens (LL) based on all-metal metamaterial is presented in this paper. To achieve the required refractive index distribution of the LL, an all-metal unit cell with a ...separated cuboid is proposed, whose height is related to its refractive index. This inserted cuboid is attached to neither the top plate nor the bottom plate of the parallel plate. Compared with traditional bed of nail design, the proposed metamaterial unit cell exhibits a wider bandwidth. The operation principle of such a unit cell is investigated using the transverse resonance technique. To construct the all-metal metamaterial LL into one body, a cruciform cuboid is added to each unit cell such that adjacent unit cells can connect to each other. Based on the designed metamaterial LL, a multibeam antenna is developed by providing seven inputs, which can generate seven predefined beams. Several parts of the prototype are separately fabricated and assembled, and good agreement is observed between simulation and measurement. The designed LL based multibeam antenna has several advantages, including wide bandwidth, high aperture efficiency, and high radiation efficiency.
A millimeter-wave (mm-wave) multibeam array antenna based on folded C-type substrate integrated waveguide (FCSIW) is presented for the first time. The design steps for its two main elements are ...described, namely an FCSIW Butler matrix (BM) and an FCSIW single-branch slot array antenna. Both of them exhibit a significant miniaturization in comparison with their substrate integrated waveguide (SIW) counterparts, leading to 40% and 33.2% reduction in occupied surface for the BM and the whole multibeam array antenna while maintaining similar performances, respectively. In addition, an optimized transition connection structure from ground coplanar waveguide (GCPW) to FCSIW is designed to facilitate the measurement of the multibeam array antenna. Finally, the FCSIW multibeam array antenna is optimized, manufactured, and measured, which can help verify the feasibility of FCSIW for the miniaturized multibeam array antenna.
A multibeam array antenna (MAA) fed by a Rotman lens with a reduced sidelobe level (SLL) is designed using a substrate integrate waveguide (SIW) technology. The designed MAA is composed of a Rotman ...lens and a 12 × 8 slot array, which functions as the beamforming network and the radiation part, respectively. To reduce the SLL in E-plane, dual-port excitations (DPEs) are applied, instead of single-port excitations (SPEs), at each feeding port of the Rotman lens. By using DPEs, a more tapered amplitude distribution can be obtained on the array elements as compared to using SPEs; therefore, the SLL is reduced from about -11 to -18 dB. The SLL in H-plane is controlled by introducing a Chebyshev distribution to the designed eight-element slot array. Based on the designed MAA, a fabricated prototype is measured to test the discrepancy between simulation and experiment.
A planar millimeter-wave 2-D beam-scanning multibeam array antenna fed by compact 16-way beam-forming network (BFN) in multilayered substrate integrated waveguide (SIW) technology is addressed. The ...BFN is formed by connecting two stacks of sub-BFNs, the E-plane sub-BFN and the H-plane sub-BFN. The H-plane sub-BFN is realized by a traditional H-plane <inline-formula> <tex-math notation="LaTeX">4 \times 4 </tex-math></inline-formula> Butler matrix (BM). The key point of this design is to propose an E-plane <inline-formula> <tex-math notation="LaTeX">4 \times 4 </tex-math></inline-formula> BM which realizes a planar E-plane sub-BFN. These two sets of sub-BFNs can joint directly without resorting to any connectors or connecting networks to form such a compact 16-way BFN with a reduced area of merely <inline-formula> <tex-math notation="LaTeX">3\lambda \times 12\lambda </tex-math></inline-formula>. After that, to be compatible with the proposed BFN, a ladder-type <inline-formula> <tex-math notation="LaTeX">4 \times 4 </tex-math></inline-formula> slot antenna array is employed, which is comprised of four linear <inline-formula> <tex-math notation="LaTeX">1 \times 4 </tex-math></inline-formula> slot antenna arrays. Different from traditional array, the four subarrays are distributed in separate layers for the purpose of jointing to the BFN more conveniently. Transition network are also required to connect the BFN with the antenna array. Finally, a compact 2-D scanning multibeam array antenna based on the planar SIW BFN are fabricated and measured, which would be an attractive candidate for 5G application.
