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Author

Kejian Wu

Bio: Kejian Wu is an academic researcher from École Polytechnique de Montréal. The author has contributed to research in topics: Printed circuit board & Microstrip. The author has an hindex of 1, co-authored 1 publications receiving 944 citations.

Papers
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Journal ArticleDOI
TL;DR: In this article, the authors provide an overview of the recent advances in the modelling, design and technological implementation of SIW structures and components, as well as their application in the development of circuits and components operating in the microwave and millimetre wave region.
Abstract: Substrate-integrated waveguide (SIW) technology represents an emerging and very promising candidate for the development of circuits and components operating in the microwave and millimetre-wave region. SIW structures are generally fabricated by using two rows of conducting cylinders or slots embedded in a dielectric substrate that connects two parallel metal plates, and permit the implementation of classical rectangular waveguide components in planar form, along with printed circuitry, active devices and antennas. This study aims to provide an overview of the recent advances in the modelling, design and technological implementation of SIW structures and components.

1,129 citations


Cited by
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Journal ArticleDOI
TL;DR: In this article, a transition printed on the same SIW substrate is proposed to improve the matching performance of SIW horn antennas in the Ku-band with a substrate thinner than λ 0/10.
Abstract: The substrate integrated waveguide (SIW) technology allows to construct several types of commonly used antennas in a planar way. However, some practical constraints limit their performances when frequencies below 20 GHz are considered. In the case of SIW horn antennas, the available substrates are much thinner than the wavelength yielding to poor matching and undesired back radiation. In this paper, an innovative structure to overcome these limitations is presented. It consists of a transition printed on the same SIW substrate, which improves both the radiation and the matching performances of conventional SIW horns. The horn shape is also further optimized by reducing its dimensions required for a given directivity. This is obtained by modifying the horn profile in order to effectively combine different TE modes. Guidelines are provided to design this type of thin and compact SIW horn antenna. They were applied to manufacture a prototype in the Ku-band with a substrate thinner than λ0/10. Measurement results validate the proposed concepts showing excellent performances.

190 citations

Journal ArticleDOI
TL;DR: In this article, the design, realization, and experimental characterization of a 400-element electronically reconfigurable transmit array operating in the Ka-band is presented, which is based on linearly polarized unitcells with 180° phase-shifting capability.
Abstract: The design, realization, and experimental characterization of a 400-element electronically reconfigurable transmitarray operating in the Ka-band is presented. It is based on linearly polarized unit-cells with 180° phase-shifting capability. Several sequential rotation schemes have been compared numerically to generate a circularly polarized beam over a broad frequency band, and a random distribution has been selected to mitigate spurious cross-polarized side-lobes when scanning the main beam. The 2-D electronic beam-steering capabilities of ±60° have been verified experimentally. The prototype, illuminated by a horn antenna as a focal source, exhibits a broadside gain of 20.8 dBi at 29.0 GHz and a 3-dB bandwidth of 14.6% with radiation efficiency of 58%. The axial ratio remains below 2 dB within this bandwidth. Next, a planar substrate integrated waveguide focal source array was designed in order to reduce the focal distance by about 50% and thereby significantly improve the antenna compactness, and similar radiation performance is demonstrated numerically and experimentally. © 1963-2012 IEEE.

188 citations

Journal ArticleDOI
TL;DR: Recent innovative methods in back radiations reduction techniques, circular polarization (CP) generation methods, dual polarization techniques, and providing additional robustness against environmental effects are presented.
Abstract: Wearable antennas have gained much attention in recent years due to their attractive features and possibilities in enabling lightweight, flexible, low cost, and portable wireless communication and sensing. Such antennas need to be conformal when used on different parts of the human body, thus need to be implemented using flexible materials and designed in a low profile structure. Ultimately, these antennas need to be capable of operating with minimum degradation in proximity to the human body. Such requirements render the design of wearable antennas challenging, especially when considering aspects such as their size compactness, effects of structural deformation and coupling to the body, and fabrication complexity and accuracy. Despite slight variations in severity according to applications, most of these issues exist in the context of body-worn implementation. This review aims to present different challenges and issues in designing wearable antennas, their material selection, and fabrication techniques. More importantly, recent innovative methods in back radiations reduction techniques, circular polarization (CP) generation methods, dual polarization techniques, and providing additional robustness against environmental effects are first presented. This is followed by a discussion of innovative features and their respective methods in alleviating these issues recently proposed by the scientific community researching in this field.

174 citations

Journal ArticleDOI
TL;DR: In this article, a printed transition is proposed to match a H-plane SIW horn antenna built in a thin substrate at different frequency bands at the Ku-band at the same time.
Abstract: The substrate integrated waveguide (SIW) technology allows to construct several types of commonly used antennas in a planar way. However, frequency limitations associated to commercial substrates appear in the implementation of certain types of antennas, e.g., SIW horn antennas are not well matched when the substrate thickness is much smaller than the wavelength. A printed transition is proposed to overcome this problem. Differently from current solutions, no bulky elements are required allowing to maintain the most important features of this technology namely its compactness and ease of manufacturing. In order to quickly analyze and design the transition, both a coupled resonator and a transmission line models are developed, together with design guidelines. The proposed transition is designed to match a H-plane SIW horn antenna built in a thin substrate $({\rm thickness} at different frequency bands at the Ku-band. Experimental results for 3 different transitions show that the matching characteristics are efficiently improved compared with the conventional SIW horn antenna and validates the proposed models.

170 citations

Journal ArticleDOI
TL;DR: In this paper, a single-layer, wideband, and low-loss corporate-feed networks for slot antenna arrays are described, where the antenna is built using ridge gap waveguide technology, formed between two parallel metal plates.
Abstract: Single-layer, wideband, and low-loss corporate-feed networks for slot antenna arrays are described. The antenna is built using ridge gap waveguide technology, formed between two parallel metal plates without the requirements of electrical contact between these plates. The corporate-feed network is realized by a texture of pins and a guiding ridge in the bottom plate, and the radiating slots are placed in the smooth top plate. The paper describes two test antennas: a 4 $\,\times\,$ 1 linear slot array and a 2 $\,\times\,$ 2 planar slot array. Both have been fabricated and tested at Ku- band. The linear array shows more than 20% bandwidth and the 2 $\,\times\,$ 2 array shows a bandwidth of 21% for 10-dB return loss. There are good agreements between measured and simulated patterns for both antennas. Measured gain for the planar array is found to be at least 12.2 dBi over 12–15 GHz band.

166 citations