The Experts below are selected from a list of 72066 Experts worldwide ranked by ideXlab platform
J J Lee - One of the best experts on this subject based on the ideXlab platform.
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ultrawideband hybrid ebg ferrite Ground Plane for low profile array antennas
IEEE Antennas and Propagation Society International Symposium, 2007Co-Authors: J M Bell, Magdy F Iskander, J J LeeAbstract:Ultrawideband and low-profile antennas are considered a most critical component in the development of low-band systems such as airborne foliage penetrating radar and EW applications. For these applications it is clear that an ultrawideband and low-profile Ground Plane needs to be developed and implemented to achieve the desired specifications and enhanced performance. In this paper a novel ultrawideband and low-profile hybrid EBG/ferrite Ground Plane is presented. The hybrid Ground Plane design offers ultrawideband operation beginning in the 100s of MHz with the presented design version offering an operational bandwidth exceeding 22:1 starting at 170 MHz. The use of this Ground Plane will allow for the practical and effective implementation of the new highly sophisticated and ultrawideband antenna systems developed at Raytheon.
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ultrawideband hybrid ebg ferrite Ground Plane for low profile array antennas
IEEE Transactions on Antennas and Propagation, 2007Co-Authors: J M Bell, Magdy F Iskander, J J LeeAbstract:The design and analysis of an ultrawideband and low-profile hybrid electromagnetic band-gap (EBG)/ferrite Ground Plane is presented for implementation with antenna systems in airborne foliage penetrating radar and EW applications. The hybrid EBG/ferrite Ground Plane consists of an EBG structure with a ferrite slab placed on top of the structure's perfect electric conductor (PEC) Ground Plane. Reflectivity and phase analyses show that the hybrid EBG/ferrite Ground Plane offers ultrawideband operation beginning in the 100s of MHz with one design version offering an operational bandwidth exceeding 22:1 starting at 170 MHz. Additionally, analysis of the hybrid Ground Plane implemented with dipole antennas verifies that the hybrid Ground Plane effectively produces uni-directional radiation for bi-directional radiating antennas. The designed hybrid Ground Plane is also simulated with Raytheon's long slot array antenna and the obtained results further verify its ultrawideband performance
J M Bell - One of the best experts on this subject based on the ideXlab platform.
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ultrawideband hybrid ebg ferrite Ground Plane for low profile array antennas
IEEE Antennas and Propagation Society International Symposium, 2007Co-Authors: J M Bell, Magdy F Iskander, J J LeeAbstract:Ultrawideband and low-profile antennas are considered a most critical component in the development of low-band systems such as airborne foliage penetrating radar and EW applications. For these applications it is clear that an ultrawideband and low-profile Ground Plane needs to be developed and implemented to achieve the desired specifications and enhanced performance. In this paper a novel ultrawideband and low-profile hybrid EBG/ferrite Ground Plane is presented. The hybrid Ground Plane design offers ultrawideband operation beginning in the 100s of MHz with the presented design version offering an operational bandwidth exceeding 22:1 starting at 170 MHz. The use of this Ground Plane will allow for the practical and effective implementation of the new highly sophisticated and ultrawideband antenna systems developed at Raytheon.
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ultrawideband hybrid ebg ferrite Ground Plane for low profile array antennas
IEEE Transactions on Antennas and Propagation, 2007Co-Authors: J M Bell, Magdy F Iskander, J J LeeAbstract:The design and analysis of an ultrawideband and low-profile hybrid electromagnetic band-gap (EBG)/ferrite Ground Plane is presented for implementation with antenna systems in airborne foliage penetrating radar and EW applications. The hybrid EBG/ferrite Ground Plane consists of an EBG structure with a ferrite slab placed on top of the structure's perfect electric conductor (PEC) Ground Plane. Reflectivity and phase analyses show that the hybrid EBG/ferrite Ground Plane offers ultrawideband operation beginning in the 100s of MHz with one design version offering an operational bandwidth exceeding 22:1 starting at 170 MHz. Additionally, analysis of the hybrid Ground Plane implemented with dipole antennas verifies that the hybrid Ground Plane effectively produces uni-directional radiation for bi-directional radiating antennas. The designed hybrid Ground Plane is also simulated with Raytheon's long slot array antenna and the obtained results further verify its ultrawideband performance
Kinlu Wong - One of the best experts on this subject based on the ideXlab platform.
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internal wwan clamshell mobile phone antenna using a current trap for reduced Ground Plane effects
IEEE Transactions on Antennas and Propagation, 2009Co-Authors: Chengtse Lee, Kinlu WongAbstract:An internal wireless wide-area network (WWAN) antenna suitable for GSM850/900/1800/1900/UMTS operation in the clamshell mobile phone with reduced Ground Plane effects is presented. Small variations in the performances of the antenna for the clamshell mobile phone in the open state (talk condition) and closed state (idle condition) are obtained. This is owing to the reduced effects of the upper (cover) Ground Plane on the performances of the internal antenna obtained by embedding a slit at the edge of the upper Ground Plane close to the connecting strip between the two (upper and main) Ground Planes of the clamshell mobile phone. In this case, large surface currents excited around the slit are achieved, with other portions of the upper Ground Plane showing much weaker surface current distributions, which makes the embedded slit behaves like a current trap for the excited surface currents. This condition results in reduced effects of the upper Ground Plane. This also makes the near-field radiation of the clamshell mobile phone with the proposed antenna easily meet the specific absorption rate (SAR) and hearing aid compatibility (HAC) specifications required for practical applications.
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internal gsm dcs antenna backed by a step shaped Ground Plane for a pda phone
IEEE Transactions on Antennas and Propagation, 2006Co-Authors: Kinlu Wong, Chuni LinAbstract:A novel internal global system for mobile communication/digital communication system (GSM/DCS) antenna suitable for application in mobile devices such as the Personal Digital Assistant (PDA) phone is presented. The antenna has two radiating strips designed to operate at about 900 and 1800 MHz for GSM/DCS operation, and is backed by and short-circuited to a step-shaped Ground Plane. With the use of the step-shaped Ground Plane, which is to be placed at the top edge of the system Ground Plane of a PDA phone, the antenna can be employed in very close proximity to the possible RF shielding metal cases for battery and associated RF module/circuitry, with almost no degradation in the antenna performances. In addition, the antenna almost occupies no board space in the system Ground Plane, and is with a very small protruded length (3 mm only in this study) over the top edge of the system Ground Plane. The antenna is thus very promising to operate as an internal antenna, and in addition, shows an attractive electromagnetic compatibility (EMC) property with nearby conducting or RF elements inside a mobile device
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finite Ground Plane effects on the ultra wideband planar monopole antenna
Microwave and Optical Technology Letters, 2004Co-Authors: Kinlu Wong, Yuantung Cheng, Wenshyang ChenAbstract:Impedance and radiation characteristics of an ultra-wideband (UWB) planar monopole antenna with a finite circular Ground Plane are experimentally studied. The significant effects of the Ground-Plane size on the lower-edge frequency of the antenna's impedance bandwidth are observed, and there exists an optimal diameter of the circular Ground Plane for achieving a maximum impedance bandwidth. Large Ground-Plane effects on the radiation pattern and antenna gain are also seen, especially for the lower frequencies in the antenna's UWB impedance bandwidth. Details of the experimental results are presented and discussed. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 535–537, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20526
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broadband probe fed patch antenna with a w shaped Ground Plane
IEEE Transactions on Antennas and Propagation, 2002Co-Authors: Kinlu Wong, Chialuan Tang, Jyhying ChiouAbstract:A new design of a broadband probe-fed patch antenna with a W-shaped Ground Plane is presented. The W-shaped Ground Plane is obtained by bending the conventional planar Ground Plane into an inverted V-shape, seen in the resonant direction of the patch antenna and then adding proper flanges at the two straight edges of the bent Ground Plane. The proposed design is applicable to the patch antenna with a planar radiating patch with a thin air substrate. With the use of the proposed W-shaped Ground Plane, the required probe-pin length in the substrate remains small, although the effective substrate thickness is significantly increased, resulting in a much wider operating bandwidth. Also, by choosing proper dimensions of the W-shaped Ground Plane, the antenna gain for frequencies over the obtained wide bandwidth is enhanced, compared to the conventional patch antenna with a planar Ground Plane. In addition, the cross polarization is also reduced for the proposed design and the cross-polarization level (XPL) in the H-Plane pattern can even be better than that of a conventional probe-fed patch antenna with a thin air substrate.
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designs of compact microstrip antennas with a slotted Ground Plane
IEEE Antennas and Propagation Society International Symposium, 2001Co-Authors: Tzungwern Chiou, Kinlu WongAbstract:It has been demonstrated that by embedding suitable slots in an antenna's radiating patch, compact microstrip antennas can be obtained. However, for such designs, the antenna gain and impedance bandwidth are also decreased, causing severe limitations for practical applications. We propose a new design of compact microstrip antennas with a slotted Ground Plane. It is found that by properly embedding a pair of narrow slots in the Ground Plane of a microstrip antenna, the antenna's fundamental resonant frequency can be lowered. Reduced antenna size at a fixed frequency can thus be achieved. Moreover, enhanced bandwidth and gain for the proposed design are also observed, which is different from that observed for compact designs with a slotted radiating patch (see Wong, K.L. and Yang, K.P., Electron. Lett., vol.33, p.1916-17, 1997; Lu, J.H. et al., IEEE Trans. Antennas Propagat., vol.47, p.1174-8, 1999). The proposed design with two pairs of narrow slots in the Ground Plane for achieving dual polarized or circularly polarized radiation has also been successfully implemented. Details of the experimental results are presented.
Magdy F Iskander - One of the best experts on this subject based on the ideXlab platform.
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ultrawideband hybrid ebg ferrite Ground Plane for low profile array antennas
IEEE Antennas and Propagation Society International Symposium, 2007Co-Authors: J M Bell, Magdy F Iskander, J J LeeAbstract:Ultrawideband and low-profile antennas are considered a most critical component in the development of low-band systems such as airborne foliage penetrating radar and EW applications. For these applications it is clear that an ultrawideband and low-profile Ground Plane needs to be developed and implemented to achieve the desired specifications and enhanced performance. In this paper a novel ultrawideband and low-profile hybrid EBG/ferrite Ground Plane is presented. The hybrid Ground Plane design offers ultrawideband operation beginning in the 100s of MHz with the presented design version offering an operational bandwidth exceeding 22:1 starting at 170 MHz. The use of this Ground Plane will allow for the practical and effective implementation of the new highly sophisticated and ultrawideband antenna systems developed at Raytheon.
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ultrawideband hybrid ebg ferrite Ground Plane for low profile array antennas
IEEE Transactions on Antennas and Propagation, 2007Co-Authors: J M Bell, Magdy F Iskander, J J LeeAbstract:The design and analysis of an ultrawideband and low-profile hybrid electromagnetic band-gap (EBG)/ferrite Ground Plane is presented for implementation with antenna systems in airborne foliage penetrating radar and EW applications. The hybrid EBG/ferrite Ground Plane consists of an EBG structure with a ferrite slab placed on top of the structure's perfect electric conductor (PEC) Ground Plane. Reflectivity and phase analyses show that the hybrid EBG/ferrite Ground Plane offers ultrawideband operation beginning in the 100s of MHz with one design version offering an operational bandwidth exceeding 22:1 starting at 170 MHz. Additionally, analysis of the hybrid Ground Plane implemented with dipole antennas verifies that the hybrid Ground Plane effectively produces uni-directional radiation for bi-directional radiating antennas. The designed hybrid Ground Plane is also simulated with Raytheon's long slot array antenna and the obtained results further verify its ultrawideband performance
John L Volakis - One of the best experts on this subject based on the ideXlab platform.
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Matching Bandwidth Limits for Arrays Backed by a Conducting Ground Plane
IEEE Transactions on Antennas and Propagation, 2013Co-Authors: Jonathan P. Doane, Kubilay Sertel, John L VolakisAbstract:Matching bandwidth limits are developed for antenna arrays backed by a perfect electrically conducting (PEC) Ground Plane. We model a general array in the long wavelength limit as a thin PEC-backed slab and use Fano's method to determine a limit for the frequency integral of the reflection coefficient. This yields a simple expression for the maximum bandwidth of the array under TE or TM excitation, subject to a specified tolerance for mismatch and efficiency. The limit also depends on the array's thickness, scan angle, and static permeability. The special case of a thin planar radiating sheet placed above a Ground Plane is also considered, which has a maximum impedance bandwidth of 8.3:1 at broadside when no materials are used $({\hbox{VSWR}}\leq {\hbox{2{:}1}})$ . Previous empirical approximations for the minimum height of a wideband array and maximum bandwidth of a tightly coupled dipole array (TCDA) are compared with the theoretical limits and found to be in good agreement.
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Interwoven Spiral Array (ISPA) With a 10:1 Bandwidth on a Ground Plane
IEEE Antennas and Wireless Propagation Letters, 2011Co-Authors: Ioannis Tzanidis, Kubilay Sertel, John L VolakisAbstract:We describe a novel, planar, circularly polarized (CP), interwoven spiral array (ISPA) having a 10:1 bandwidth while operating conformally on a perfect electric conducting (PEC) Ground Plane. The array is comprised of rectangular, self-complementary spirals. However, unlike typical array designs, the elements have their arms "interwoven" to enhance coupling. This coupling serves to mitigate the inductive effects contributed by the PEC Ground Plane. Consequently, the unit cell of the array encompasses several adjacent array elements. This feature leads to unique array properties, and in this letter, we pursue a numerical analysis and design of an array version that delivers a 10:1 bandwidth, for a broadside scan, in a conformal setting.
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impedance matched ferrite layers as Ground Plane treatments to improve antenna wide band performance
IEEE Transactions on Antennas and Propagation, 2009Co-Authors: F Erkmen, Chichih Chen, John L VolakisAbstract:In low-profile applications, Ground Plane backing significantly degrades antenna performance when the electrical height is a small fraction of a wavelength. An approach to suppress the destructive interference from the Ground Plane reflections is to employ absorbing layers of ferrite materials. In this paper, we introduce a means to also control and utilize the mode excited in these finite ferrite layers to recover antenna performance at ultra/very high frequencies. Experimental verification is provided using commercial ferrite materials.
