Search

Holography based on optical metasurfaces has attracted a steadily increasing interest. However, most of the optical metasurfaces usually suffer from limited number and fixed viewing angles of multiplexed holography images in one channel. Here, by modifying the Gerchberg–Saxton algorithm, a multiplexed holography at arbitrary‐planes is proposed at two arbitrary microwave frequency bands. As a proof‐of‐concept demonstration, two independent information channels can be established by a single metasurface through dual‐frequency meta‐atoms. The metasurface composed of 35 × 35 meta‐atoms can simultaneously produce four images with 45° and 60° viewing angles at 10 GHz and five images with vertical and horizontal viewing angles at 16 GHz. The experimental results verify the design concept, making it possible to generate multiplexed holography in arbitrary‐planes, and allowing multiplexed functionalities in a variety of applications such as microscopy, display, security, data storage, and information processing. [ABSTRACT FROM AUTHOR]

A direction of arrival (DoA) estimation technique for broadband microwave signals is proposed using a single ultrawideband antenna. It is inspired by the sound source localization ability of a human auditory system using just one ear (monaural localization). By exploiting the incident angle-dependent frequency response of a wideband antenna, the DoA of a broadband microwave signal can be estimated. The DoA estimation accuracies are evaluated for two antenna configurations and microwave signals with different signal-to-noise ratios. Encouraging the DoA estimation performance of the proposed technique is demonstrated in both simulation and experiment. [ABSTRACT FROM AUTHOR]

ABSTRACT This article presents a dual-band amplifier with flexible frequency ratios. The amplifier features novel Wilkinson power divider/combiner with dual-band property that allows large frequency ratio (2.16-4.9) between its first and second operating bands. The measured combining efficiency on a stand-alone combiner is 97% at 2.25 GHz and 75% at 5.25 GHz. A 2.25/5.5 GHz prototype amplifier is tested to verify dual-band functionality. Measured linear gains are 12.85 dB and 12.07 dB at the first and second frequency bands, respectively. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:2242-2247, 2015 [ABSTRACT FROM AUTHOR]

In this article, the coupling coefficients of the coupled-resonator filters are extracted using the genetic algorithms (GA). To demonstrate the feasibility of the proposed method, filters with different orders and different characteristics are tested. In all cases, the parameters of these filters can be efficiently identified without any a priori knowledge. © 2011 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2011. [ABSTRACT FROM AUTHOR]

A low-profile, compact and easily integrated antenna for RF/microwave applications is presented in this article. The designed antenna works around 430 MHz and can be easily scaled to other frequencies. Metamaterial-inspired slot loop antennas are used as the radiating elements. To shrink the total size of the antenna, periodical structures are loaded to the original slot loop. It is found that with this modification, the total size of the antenna is reduced and the impedance matching of the antenna is improved. To further improve the performance of the proposed antenna, a floating ground plane and a parasitic slot were added, made possible by the multilayered structure of the antenna. As a result, the bandwidth and gain of proposed antenna are increased. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:219-223, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25654 [ABSTRACT FROM AUTHOR]