Artificial Magnetic Conductor as Planar Antenna for 5G Evolution

A 5G wireless system requests a high-performance compact antenna device. This research work aims to report the characterization and verification of the artificial magnetic conductor (AMC) metamaterial for a high-gain planar antenna. The configuration is formed by a double-side structure on an intrinsic dielectric slab. The 2-D periodic pattern as an impedance surface is mounted on the top surface, whereas at the bottom surface the ground plane with an inductive narrow aperture source is embedded. The characteristic of the resonant transmission is illustrated based on the electromagnetic virtual object of the AMC resonant structure to reveal the unique property of a magnetic material response. The characteristics of the AMC metamaterial and the planar antenna synthesis are investigated and verified by experiment using a low-cost FR4 dielectric material. The directional antenna gain is obviously enhanced by guiding a primary field radiation. The loss effect in a dielectric slab is essentially studied having an influence on antenna radiation. The verification shows a peak of the antenna gain around 9.7 dB at broadside which is improved by 6.2 dB in comparison with the primary aperture antenna without the AMC structure. The thin antenna profile of λ/37.5 is achieved at 10 GHz for 5G evolution. The emission property in an AMC structure herein contributes to the development of a low-profile and high-gain planar antenna for a compact wireless component.     

Hardware-assisted initialisation for constant modulus algorithm adaptive antenna

A cost-effective approach for initialisation of an adaptive antenna based on the constant modulus algorithm (CMA) is proposed. The technique utilises 1 bit phase shifters and a power detector, which are normally integrated with a multibeam antenna, to determine the maximum power beam direction. Consequently, the beam is exploited as an initial beam for CMA. Development of hardware-assisted initialisation is discussed. In addition, field programmable gate array implementation of a CMA processor and associated control circuitry is presented. Several simulations are performed to evaluate the performance of the proposed initialisation technique. In addition, the developed prototype is tested with a phase array antenna designed for operation at the IMT2000 frequency of 1.95 GHz. Experimental results confirm superiority of the proposed technique.     

Dependence of zinc aluminate microscopic structure on its synthesis

Alumina doped with zinc oxide was synthesized by sol–gel method in alcohol solution. Hybrid oxides of aluminum and zinc were prepared from various aluminum precursors (aluminum sec-butoxide, aluminum nitrate, and aluminum isopropoxide) and zinc acetate solution with ethylacetoacetate and nitric acid as a chelating agent and catalyst, respectively. Types and molar ratio of the precursor to the chelating agent and acidic catalyst were found to remarkably affect the formation of transparent sol of aluminium–zinc sol composite. With relatively low temperature of 50 °C, the suitable molar ratio of aluminum sec-butoxide to ethylacetoacetate to nitric acid for preparing the homogeneous sol was 1:0.40:0.86. Furthermore, the calcination at elevated temperature higher than 400 °C would be essential for preparing ZnAl₂O₄ with the face centered cubic microstructure. The primary crystalline size of the synthesized zinc aluminate nanostructure was approximately 20 nm with lattice spacing of 0.55 nm.