The Experts below are selected from a list of 25944 Experts worldwide ranked by ideXlab platform
K M Luk - One of the best experts on this subject based on the ideXlab platform.
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a water dense dielectric Patch Antenna
IEEE Access, 2015Co-Authors: K M LukAbstract:A novel water dense dielectric Patch Antenna (DDPA) fed by an L-shaped probe is proposed and investigated. In contrast to the water Antennas in the literature, including the water monopole and the water dielectric resonator Antenna, the operation mechanism of the proposed water DDPA is similar to the conventional metallic Patch Antenna. The Antenna is excited in a mode like the TM $_{{\textrm {10}}}$ mode of the rectangular Patch Antenna. An L-shaped probe, which is widely used for the conventional Patch Antenna, is used to excite the water DDPA. A study on the bandwidth performance of the proposed design reveals that wide bandwidth can be achieved for the Antenna by choosing a thick supporting substrate between the water Patch and the ground plane. A prototype is fabricated to confirm the correctness of the design. An impedance bandwidth of 8%, maximum gain of 7.3 dBi, radiation efficiency up to 70%, and symmetrically unidirectional patterns with low backlobe and low cross polarization levels are obtained. Furthermore, owing to the transparency of the water Patch, the proposed water DDPA can be conveniently integrated with the solar cells to realize a dual-function design. Measurements on the prototype demonstrate that the existence of the solar cells does not significantly affect the performance of the Antenna and vice versa.
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dense dielectric Patch Antenna a new kind of low profile Antenna element for wireless communications
IEEE Transactions on Antennas and Propagation, 2013Co-Authors: Hau Wah Lai, K M Luk, K W LeungAbstract:By replacing the metallic Patch of a microstrip Antenna with a high permittivity thin dielectric slab, a new type of Patch Antenna, designated as the dense dielectric Patch Antenna (DD Patch Antenna), is proposed. At lower microwave frequencies, it has similar performance as the conventional metallic circular microstrip Antenna operated in the fundamental TM11 mode. A prototype operated at 3.98 GHz exhibits an impedance bandwidth of 1% and a gain of 5.6 dBi. Due to the absence of the metallic Patch, it is expected that this Antenna has better radiation efficiency at millimeter wave and terahertz frequencies in comparison with the conventional microstrip Patch Antenna.
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small circularly polarized u slot wideband Patch Antenna
IEEE Antennas and Wireless Propagation Letters, 2011Co-Authors: Ka Ya Lam, Kai Fang Lee, K M Luk, Hang WongAbstract:A single-feed circularly polarized (CP) Patch Antenna at L-band is designed and built using the recently developed U-slot loaded Patch technique. With the presence of the U-slot, the Antenna fabricated on a high-dielectric-constant (er = 10.02) substrate achieves a reasonable axial-ratio bandwidth. At the operating frequency of 1.575 GHz, the size of the Patch is 0.13λo × 0.13λo, while the ground size is 0.315λo × 0.315λo and the thickness of the substrate is 0.05λo. The measured gain is 4.5 dBi, and axial-ratio bandwidth is 3.2%.
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virtually shorted Patch Antenna for circular polarization
IEEE Antennas and Wireless Propagation Letters, 2010Co-Authors: Hang Wong, K M Luk, Chi Hou Cha, Qua XueAbstract:This letter presents a new circularly polarized Patch Antenna with loaded shorting elements to achieve symmetric broadside radiation and size reduction. The loaded elements are parasitic to the driven Patch, but are shorted to the ground plane. Conventionally, shorting pins or walls are a common technique for reducing the size of the Antenna. However, deterioration in broadside radiation with high cross-polar level occurs. The proposed shorting elements provide a solution for size reduction of the radiating Patch while maintaining good broadside radiation pattern. Since the radiating Patch is effectively shorted to the ground at the operating frequency, it is designated as a virtually shorted Patch Antenna (VSPA).
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the versatile u slot Patch Antenna
IEEE Antennas and Propagation Magazine, 2010Co-Authors: Kai Fang Lee, Ahmed A Kishk, S L S Yang, K M LukAbstract:The U-slot Patch Antenna was originally developed as a single-layer, single-Patch wideband Antenna. It has recently been shown that it can also be designed to perform a number of other functions. In this paper, a comprehensive account is given on the development of this Antenna. Emphasis is placed on experimental and simulation results for various U-slot topologies, illustrating the Antenna's versatility in several practical applications. These include wideband, dual- and triple-band operation with small and large frequency ratios, as well as for circular-polarization applications.
Hang Wong - One of the best experts on this subject based on the ideXlab platform.
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miniaturized circularly polarized Patch Antenna with low back radiation for gps satellite communications
IEEE Transactions on Antennas and Propagation, 2015Co-Authors: Kwok Kan So, Hang Wong, Chi Hou ChanAbstract:A new size-reduction technique for circularly polarized (CP) Patch Antenna with the use of parasitic shorting strips is presented. The operating frequency of the CP Patch Antenna can be controlled by those parasitic shorting strips. Rectangular, U-shaped, and meandering shorting strips are studied. It is found that the size and the back radiation of the Patch Antenna can be reduced simultaneously. Good impedance matching and CP radiation characteristics can be achieved with different shapes of the shorting strips. The proposed Antenna with meandering shorting strip is measured. Good agreement between analytical and experimental results is obtained.
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design and analysis of a low profile and broadband microstrip monopolar Patch Antenna
IEEE Transactions on Antennas and Propagation, 2013Co-Authors: Juhua Liu, Hau Wah Lai, Hang Wong, Quan Xue, Yunliang LongAbstract:A new microstrip monopolar Patch Antenna is proposed and analyzed. The Antenna has a wide bandwidth and a monopole like radiation pattern. Such Antenna is constructed on a circular Patch Antenna that is shorted concentrically with a set of conductive vias. The Antenna is analyzed using a cavity model. The cavity model analysis not only distinguishes each resonating mode and gives a physical insight into each mode of the Antenna, but also provides a guideline to design a broadband monopolar Patch Antenna that utilizes two modes (TM01 and TM02 modes). Both modes provide a monopole like radiation pattern. The proposed Antenna has a simple structure with a low profile of 0.024 wavelengths, and yields a wide impedance bandwidth of 18% and a maximum gain of 6 dBi.
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small circularly polarized u slot wideband Patch Antenna
IEEE Antennas and Wireless Propagation Letters, 2011Co-Authors: Ka Ya Lam, Kai Fang Lee, K M Luk, Hang WongAbstract:A single-feed circularly polarized (CP) Patch Antenna at L-band is designed and built using the recently developed U-slot loaded Patch technique. With the presence of the U-slot, the Antenna fabricated on a high-dielectric-constant (er = 10.02) substrate achieves a reasonable axial-ratio bandwidth. At the operating frequency of 1.575 GHz, the size of the Patch is 0.13λo × 0.13λo, while the ground size is 0.315λo × 0.315λo and the thickness of the substrate is 0.05λo. The measured gain is 4.5 dBi, and axial-ratio bandwidth is 3.2%.
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virtually shorted Patch Antenna for circular polarization
IEEE Antennas and Wireless Propagation Letters, 2010Co-Authors: Hang Wong, K M Luk, Chi Hou Cha, Qua XueAbstract:This letter presents a new circularly polarized Patch Antenna with loaded shorting elements to achieve symmetric broadside radiation and size reduction. The loaded elements are parasitic to the driven Patch, but are shorted to the ground plane. Conventionally, shorting pins or walls are a common technique for reducing the size of the Antenna. However, deterioration in broadside radiation with high cross-polar level occurs. The proposed shorting elements provide a solution for size reduction of the radiating Patch while maintaining good broadside radiation pattern. Since the radiating Patch is effectively shorted to the ground at the operating frequency, it is designated as a virtually shorted Patch Antenna (VSPA).
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Wideband Shorted Bowtie Patch Antenna With Electric Dipole
IEEE Transactions on Antennas and Propagation, 2008Co-Authors: Hang WongAbstract:A wideband directional Antenna composed of a shorted bowtie Patch Antenna and an electric dipole is presented. Through this composition, an equivalent magnetic dipole due to the shorted bowtie Patch Antenna and an electric dipole are excited together. Almost equal radiation pattern in the E- and H-planes is obtained. The proposed Antenna has a wide impedance bandwidth, which is over 60% for SWR. < 2 ranging from 2.16-4.13 GHz.
Yongxi Guo - One of the best experts on this subject based on the ideXlab platform.
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capacitively loaded circularly polarized implantable Patch Antenna for ism band biomedical applications
IEEE Transactions on Antennas and Propagation, 2014Co-Authors: Changrong Liu, Yongxi Guo, Shaoqiu XiaoAbstract:A single-fed miniaturized circularly polarized microstrip Patch Antenna is designed and experimentally demonstrated for industrial-scientific-medical (2.4-2.48 GHz) biomedical applications. The proposed Antenna is designed by utilizing the capacitive loading on the radiator. Compared with the initial topology of the proposed Antenna, the so-called square Patch Antenna with a center-square slot, the proposed method has the advantage of good size reduction and good polarization purity. The footprint of the proposed Antenna is 10×10×1.27 mm3. The simulated impedance, axial ratio, and radiation pattern are studied and compared in two simulation models: cubic skin phantom and Gustav voxel human body. The effect of different body phantoms is discussed to evaluate the sensitivity of the proposed Antenna. The effect of coaxial cable is also discussed. Two typical approaches to address the biocompatibility issue for practical applications are reported as well. The simulated and measured impedance bandwidths in cubic skin phantom are 7.7% and 10.2%, respectively. The performance of the communication link between the implanted CP Antenna and the external Antenna is also presented.
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wideband circularly polarized Patch Antenna using broadband baluns
IEEE Transactions on Antennas and Propagation, 2008Co-Authors: Yongxi Guo, Kahwee Khoo, L C OngAbstract:A novel 90deg broadband balun comprising a broadband 90deg Schiffman phase shifter is introduced as a means of enhancing the wideband circular polarization performance of dual-fed type microstrip Antennas. The proposed 90deg broadband balun delivers good impedance matching, balanced power splitting and consistent 90deg (plusmn5deg) phase shifting, across a wide bandwidth (~57.5%). A circular Patch Antenna utilizing the proposed 90deg broadband balun is shown to attain measured impedance(S11< -10 dB) and axial ratio (AR < 3 dB) bandwidths of 60.24% and 37.7%, respectively, for the dual L-probe case; and 71.28% and 81.6% respectively, for the quadruple L-probe case.
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wideband circularly polarized Patch Antenna
IEEE Transactions on Antennas and Propagation, 2006Co-Authors: Yongxi Guo, L C Ong, Xiangqua ShiAbstract:A novel wideband circularly-polarized Patch Antenna is presented. First, a new broadband 90deg hybrid feed network is proposed to have a bandwidth of 75% for the 10-dB return loss, good two output ports amplitude balance and a consistent 90deg (plusmn3deg) phase difference between two output ports. Then, a circular Patch Antenna fed by four sequential-rotation proximity-coupled L-probes orientated to have phase of 0deg, 90deg, 180deg and 270deg is presented. The four L-probes are connected to the respective ports of a feed network comprising a pair of the proposed broadband 90deg hybrid. It is found that the Antenna can deliver a measured impedance bandwidth of 79.4% from 1.04 to 2.41 GHz for SWR 3 dBi. The simulated impedance bandwidth is 94% from 0.9 to 2.5 GHz for SWR 3 dBi. Good agreement is observed between simulation and measurement
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wideband circularly polarized Patch Antenna
Asia-Pacific Microwave Conference, 2005Co-Authors: Yongxi Guo, L C Ong, Xiangqua ShiAbstract:In this paper, a novel wideband circularly-polarized Patch Antenna is presented. The Patch Antenna is excited by a broadband feed network having a 10-dB return loss bandwidth of 86% and a consistent 90/spl deg/ (/spl plusmn/ 3/spl deg/) phase difference between two output ports over a wideband of 76%. It is found that the Antenna can deliver a measured impedance bandwidth of 79.4% for SWR 3dBi.
Hau Wah Lai - One of the best experts on this subject based on the ideXlab platform.
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circularly polarized Patch Antenna for future 5g mobile phones
IEEE Access, 2014Co-Authors: Ka Ming Mak, Hau Wah Lai, Kwai-man Luk, Chi Hou ChanAbstract:A circularly polarized Patch Antenna for future fifth-generation mobile phones is presented in this paper. Miniaturization and beamwidth enhancement of a Patch Antenna are the two main areas to be discussed. By folding the edge of the radiating Patch with loading slots, the size of the Patch Antenna is 44.8% smaller than a conventional half wavelength Patch, which allows it to be accommodated inside handsets easily. Wide beamwidth is obtained by surrounding the Patch with a dielectric substrate and supporting the Antenna by a metallic block. A measured half power beamwidth of 124° is achieved. The impedance bandwidth of the Antenna is over 10%, and the 3-dB axial ratio bandwidth is 3.05%. The proposed Antenna covers a wide elevation angle and complete azimuth range. A parametric study of the effect of the metallic block and the surrounding dielectric substrate on the gain at a low elevation angle and the axial ratio of the proposed Antenna are presented.
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dense dielectric Patch Antenna a new kind of low profile Antenna element for wireless communications
IEEE Transactions on Antennas and Propagation, 2013Co-Authors: Hau Wah Lai, K M Luk, K W LeungAbstract:By replacing the metallic Patch of a microstrip Antenna with a high permittivity thin dielectric slab, a new type of Patch Antenna, designated as the dense dielectric Patch Antenna (DD Patch Antenna), is proposed. At lower microwave frequencies, it has similar performance as the conventional metallic circular microstrip Antenna operated in the fundamental TM11 mode. A prototype operated at 3.98 GHz exhibits an impedance bandwidth of 1% and a gain of 5.6 dBi. Due to the absence of the metallic Patch, it is expected that this Antenna has better radiation efficiency at millimeter wave and terahertz frequencies in comparison with the conventional microstrip Patch Antenna.
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design and analysis of a low profile and broadband microstrip monopolar Patch Antenna
IEEE Transactions on Antennas and Propagation, 2013Co-Authors: Juhua Liu, Hau Wah Lai, Hang Wong, Quan Xue, Yunliang LongAbstract:A new microstrip monopolar Patch Antenna is proposed and analyzed. The Antenna has a wide bandwidth and a monopole like radiation pattern. Such Antenna is constructed on a circular Patch Antenna that is shorted concentrically with a set of conductive vias. The Antenna is analyzed using a cavity model. The cavity model analysis not only distinguishes each resonating mode and gives a physical insight into each mode of the Antenna, but also provides a guideline to design a broadband monopolar Patch Antenna that utilizes two modes (TM01 and TM02 modes). Both modes provide a monopole like radiation pattern. The proposed Antenna has a simple structure with a low profile of 0.024 wavelengths, and yields a wide impedance bandwidth of 18% and a maximum gain of 6 dBi.
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dual polarized Patch Antenna fed by meandering probes
IEEE Transactions on Antennas and Propagation, 2007Co-Authors: Hau Wah Lai, K M LukAbstract:A dual polarized Patch Antenna fed by meandering probes is presented. The Antenna achieves an impedance bandwidth (SWR < 2) of 26% at each input port. By locating the meandering probes appropriately, the Antenna has isolation more than 25 dB, which can be further enhanced to more than 30 dB by surrounding the Antenna with vertical metallic walls. The gain of the Antenna is about 10 dBi across the operating bandwidth.
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design and study of wide band Patch Antenna fed by meandering probe
IEEE Transactions on Antennas and Propagation, 2006Co-Authors: Hau Wah Lai, K M LukAbstract:A wide-band probe fed Patch Antenna with low cross polarization and symmetrical broadside radiation pattern is proposed and studied. By employing a novel meandering probe feed and locating a Patch about 0.1/spl lambda//sub 0/ above a ground plane, a Patch Antenna with 30% impedance bandwidth (SWR<2) and 9 dBi gain is designed. The far field radiation pattern of the Antenna is stable across the operating bandwidth. Parametric studies and design guidelines of the proposed feeding structure are provided.
L C Ong - One of the best experts on this subject based on the ideXlab platform.
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wideband circularly polarized Patch Antenna using broadband baluns
IEEE Transactions on Antennas and Propagation, 2008Co-Authors: Yongxi Guo, Kahwee Khoo, L C OngAbstract:A novel 90deg broadband balun comprising a broadband 90deg Schiffman phase shifter is introduced as a means of enhancing the wideband circular polarization performance of dual-fed type microstrip Antennas. The proposed 90deg broadband balun delivers good impedance matching, balanced power splitting and consistent 90deg (plusmn5deg) phase shifting, across a wide bandwidth (~57.5%). A circular Patch Antenna utilizing the proposed 90deg broadband balun is shown to attain measured impedance(S11< -10 dB) and axial ratio (AR < 3 dB) bandwidths of 60.24% and 37.7%, respectively, for the dual L-probe case; and 71.28% and 81.6% respectively, for the quadruple L-probe case.
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wideband circularly polarized Patch Antenna
IEEE Transactions on Antennas and Propagation, 2006Co-Authors: Yongxi Guo, L C Ong, Xiangqua ShiAbstract:A novel wideband circularly-polarized Patch Antenna is presented. First, a new broadband 90deg hybrid feed network is proposed to have a bandwidth of 75% for the 10-dB return loss, good two output ports amplitude balance and a consistent 90deg (plusmn3deg) phase difference between two output ports. Then, a circular Patch Antenna fed by four sequential-rotation proximity-coupled L-probes orientated to have phase of 0deg, 90deg, 180deg and 270deg is presented. The four L-probes are connected to the respective ports of a feed network comprising a pair of the proposed broadband 90deg hybrid. It is found that the Antenna can deliver a measured impedance bandwidth of 79.4% from 1.04 to 2.41 GHz for SWR 3 dBi. The simulated impedance bandwidth is 94% from 0.9 to 2.5 GHz for SWR 3 dBi. Good agreement is observed between simulation and measurement
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wideband circularly polarized Patch Antenna
Asia-Pacific Microwave Conference, 2005Co-Authors: Yongxi Guo, L C Ong, Xiangqua ShiAbstract:In this paper, a novel wideband circularly-polarized Patch Antenna is presented. The Patch Antenna is excited by a broadband feed network having a 10-dB return loss bandwidth of 86% and a consistent 90/spl deg/ (/spl plusmn/ 3/spl deg/) phase difference between two output ports over a wideband of 76%. It is found that the Antenna can deliver a measured impedance bandwidth of 79.4% for SWR 3dBi.
