A novel fractal wideband artificial magnetic conductor (AMC) structure is designed as the ground plane of a printed bow-tie antenna for gain enhancement and low profile. The origin printed bow-tie antenna is operated in the range from 1.67 to 2.06 GHz for a VSWR <2. The AMC structure consists of 6 × 9 first-order fractal unit cells that are made up of four circles and four smaller circles, and the ±90°reflection phase band is 1.1-3.03 GHz. Both the AMC ground plane and bow-tie antenna are fabricated and measured. The distance between the antenna and the AMC is reduced to one-eighth of the wavelength in free space at 1.7 GHz. The experimental results show that the composite antenna has a wide bandwidth from 1.64 to 1.94 GHz, with a relative frequency bandwidth of 16.7%.Introduction: Over the last decade, artificial electromagnetic materials, which are manufactured by arranging patches periodically in two or three dimensions, have attracted a lot of interest because of their appealing properties. The artificial magnetic conductor (AMC), one of the artificial electromagnetic materials, is well known for its superior property of in-phase reflection [1][2][3]. The distance between the antenna and the perfect electric conductor should be at least λ/4 for gain enhancement. However, the reflection of the AMC ground plane is in-phase, which means a zero-phase delay in the designed band. So, the AMC ground plane should be very close to the antenna to enhance the antenna gain and this is the reason why the AMC is suitable for low-profile antenna design.A lot of work and advances have been reported in [4][5][6][7]. However, the major disadvantage of the AMC is the narrow bandwidth, which limits its applications. Therefore, the challenge is to improve its in-phase reflection bandwidth. Furthermore, incidence angle and polarisation sensitivity should also be improved. Based on the plum-shaped unit cell of AMC structure in [5], a novel fractal AMC structure is proposed in this Letter. A printed bow-tie antenna is designed that operates in the frequency range from 1.67 to 2.06 GHz and the ±90°reflection phase bandwidth of the novel AMC structure is 1.1-3.03 GHz. Then, the bow-tie antenna and the AMC structure are integrated to realise a lowprofile wideband antenna with an enhanced gain. The simulation and experimental results are presented, including the reflection phase characteristics, S-parameters, gain and radiation patterns.

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A novel microstrip slot antenna for ultrawideband (UWB) applications is presented. A circular patch with a tapered microstrip line above an elliptical slot ground plane is adopted for achieving a wide frequency bandwidth (BW). Two circular slots on the ground plane combined with two semicircular slots and four quasi-triangular slots on the circular patch are designed for BW enhancement and decreasing the lower cut-off frequency f L . An UWB antenna with a compact size of 300 3 300 mm 2 is obtained with relative BW of 187%, which covers 0.34-10.28 GHz. The simulation and experimental results are presented, demonstrating the UWB characteristics of the proposed antenna for wireless communication applications. V C 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:325-328, 2015; View this article online at wileyonlinelibrary.com.

This paper presents the "model construction method", an optimization method and industrial internet of things (IIoT) technology that is proposed for nearly zero energy buildings (nZEB), providing a comfortable visual environment by only utilizing natural light while improving its induced indoor air conditioner energy consumption (ACEC). The incident light is sampled by light sensors, and this data is sent to the cloud server. The visual comfort and indoor ACEC, both of which are induced by incident light, are combined as the optimization objective, and the area of windows covered by curtains is used as the optimal parameter in the particle swarm optimization (PSO). The visual comfort and indoor ACEC induced by incident light are modeled, and the construction method is independent of the geographical location. Five modes are defined for applications with different purposes, the performance of which are investigated and compared carefully. The result shows that natural light could provide comfortable visual comfort, while the ACEC induced by it could be reduced effectively.