Showing papers on "Slot antenna published in 2004"
TL;DR: In this article, the authors applied the spherical dyadic Green's function (DGF) expansions and finite-difference time-domain (FDTD) code to analyze the electromagnetic characteristics of dipole antennas and low-profile patch antennas implanted in the human head and body.
Abstract: Antennas implanted in a human body are largely applicable to hyperthermia and biotelemetry. To make practical use of antennas inside a human body, resonance characteristics of the implanted antennas and their radiation signature outside the body must be evaluated through numerical analysis and measurement setup. Most importantly, the antenna must be designed with an in-depth consideration given to its surrounding environment. In this paper, the spherical dyadic Green's function (DGF) expansions and finite-difference time-domain (FDTD) code are applied to analyze the electromagnetic characteristics of dipole antennas and low-profile patch antennas implanted in the human head and body. All studies to characterize and design the implanted antennas are performed at the biomedical frequency band of 402-405 MHz. By comparing the results from two numerical methodologies, the accuracy of the spherical DGF application for a dipole antenna at the center of the head is evaluated. We also consider how much impact a shoulder has on the performance of the dipole inside the head using FDTD. For the ease of the design of implanted low-profile antennas, simplified planar geometries based on a real human body are proposed. Two types of low-profile antennas, i.e., a spiral microstrip antenna and a planar inverted-F antenna, with superstrate dielectric layers are initially designed for medical devices implanted in the chest of the human body using FDTD simulations. The radiation performances of the designed low-profile antennas are estimated in terms of radiation patterns, radiation efficiency, and specific absorption rate. Maximum available power calculated to characterize the performance of a communication link between the designed antennas and an exterior antenna show how sensitive receivers are required to build a reliable telemetry link.
739 citations
TL;DR: By etching longitudinal slots on the top metallic surface of the substrate integrated waveguide (SIW), an integrated slot-array antenna is proposed in this article, which takes the advantage of small size, low profile, and low cost, etc.
Abstract: By etching longitudinal slots on the top metallic surface of the substrate integrated waveguide (SIW), an integrated slot-array antenna is proposed in this letter. The whole antenna and feeding system are fabricated on a single substrate, which takes the advantage of small size, low profile, and low cost, etc. The design process and experimental results of a four-by-four SIW slot array antenna at X-band are presented.
498 citations
TL;DR: In this article, a new ultra-wideband (UWB) antenna for UWB applications is proposed, which is designed to operate from 3.2 to 12 GHz and consists of a rectangular patch with two steps, a single slot on the patch, and a partial ground plane.
Abstract: In this paper, we propose a new ultra-wideband (UWB) antenna for UWB applications. The proposed antenna is designed to operate from 3.2 to 12 GHz. It consists of a rectangular patch with two steps, a single slot on the patch, and a partial ground plane. Details of the proposed antenna design and measured results are presented and discussed. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 40: 399–401, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11392
304 citations
TL;DR: A small and low-cost antenna solution for radio frequency identification (RFID) tags is presented that is applicable in many different environments because the impedance of the antenna is immune to the platform.
Abstract: A small and low-cost antenna solution for radio frequency identification (RFID) tags is presented. The impedance of the antenna is designed to match directly to the impedance of the RFID microchip. Also, the impedance of the antenna is immune to the platform. Thus, the antenna is applicable in many different environments. The design and measurement results are reported and discussed.
238 citations
TL;DR: In this article, an experimental investigation was conducted on printed wide-slot antennas fed by microstrip lines for wideband applications, and two designs with significantly enhanced impedance bandwidths and improved radiation patterns were obtained.
Abstract: An experimental investigation was conducted on printed wide-slot antennas fed by microstrip lines for wideband applications. Results show that the impedance matching of this kind of antenna is greatly affected by the feed-slot combination and feed gap width, with the slot shape being a main contributor of the radiation characteristics. By properly choosing suitable slot shapes, selecting similar feed shapes and tuning their dimensions, two designs with significantly enhanced impedance bandwidths and improved radiation patterns are obtained.
238 citations
Patent•
02 Feb 2004
TL;DR: In this article, the authors proposed a multi-band planar antenna applicable as an internal antenna in small-sized mobile stations, and to a radio device including an antenna according to the invention, based on a conventional dual band PIFA with its feeding and shorting conductors and a non-conducting slot.
Abstract: A multi-band planar antenna applicable as an internal antenna in small-sized mobile stations, and to a radio device including an antenna according to the invention. The basis is a conventional dual band PIFA with its feeding and shorting conductors and a non-conducting slot. The planar element ( 220 ) has a second slot ( 232 ) known as such, which starts at the edge of the planar element on the other side of the feeding conductor ( 221 ) and shorting conductor ( 211 ) than the above-mentioned slot ( 231 ). In addition the structure comprises a second shorting conductor ( 212 ) on the other side of the second slot, than the feeding conductor. The second slot acts as a radiator, which for instance broadens the upper band of a dual band antenna. The second shorting conductor facilitates a better matching of a multi-band antenna than in corresponding prior art antennas. The antenna is simple, and its manufacturing costs are relatively low.
233 citations
TL;DR: In this paper, an ultrawide-band coplanar waveguide (CPW) fed slot antenna is presented, which is excited by a 50/spl Omega/CPW with a U-shaped tuning stub.
Abstract: An ultrawide-band coplanar waveguide (CPW) fed slot antenna is presented. A rectangular slot antenna is excited by a 50-/spl Omega/ CPW with a U-shaped tuning stub. The impedance bandwidth, from both measurement and simulation, is about 110% (S11<-10 dB). The antenna radiates bi-directionally. The radiation patterns obtained from simulations are found to be stable across the matching band and experimental verification is provided at the high end of the band.
221 citations
TL;DR: In this paper, a new idea of increasing operational bandwidth of a compact planar inverted F antenna (PIFA) by introducing open-end slots in the ground plane under the radiating patch is described.
Abstract: This letter describes a new idea of increasing operational bandwidth of a compact planar inverted F antenna (PIFA) by introducing open-end slots in the ground plane under the radiating patch. The slots are not in the way of active modules of a wireless transceiver and thus the proposed antenna size reduction method is attractive from the point of view of practical implementation.
196 citations
TL;DR: In this paper, the simulation and experimental investigations of a printed microstrip slot antenna are presented, which is a quarter wavelength monopole slot cut in the finite ground plane edge, and fed electromagnetically by a microstrip transmission line.
Abstract: This paper presents the simulation and experimental investigations of a printed microstrip slot antenna. It is a quarter wavelength monopole slot cut in the finite ground plane edge, and fed electromagnetically by a microstrip transmission line. It provides a wide impedance bandwidth adjustable by variation of its parameters, such as the relative permittivity and thickness of the substrate, width, and location of the slot in the ground plane, and feed and ground plane dimensions. The ground plane is small, 50 mm/spl times/80 mm, and is about the size of a typical PC wireless card. At the center frequency of 3.00 GHz, its width of 50 mm is about /spl lambda//2 and influences the slot impedance and bandwidth significantly. An impedance bandwidth (S/sub 11/=-10 dB) of up to about 60% is achieved by individually optimizing its parameters. The simulation results are confirmed experimentally. A dual complementary slot antenna configuration is also investigated for the polarization diversity.
174 citations
Patent•
18 Jun 2004TL;DR: In this paper, the authors present a surface wave plasma treatment apparatus composed of a plasma treatment chamber including a part where the chamber is formed as a dielectric window capable of transmitting a microwave.
Abstract: A surface wave plasma treatment apparatus according to the present invention is a surface wave plasma treatment apparatus composed of a plasma treatment chamber including a part where the chamber is formed as a dielectric window capable of transmitting a microwave, a supporting body of a substrate to be treated, the supporting body set in the plasma treatment chamber, a plasma treatment gas introducing unit for introducing a plasma treatment gas into the plasma treatment chamber, an exhaust unit for evacuating an inside of the plasma treatment chamber, and a microwave introducing unit using a multi-slot antenna arranged on an outside of the dielectric window to be opposed to the supporting unit of the substrate to be treated, wherein slots arranged radially and slots arranged annularly are combined as slots.
160 citations
TL;DR: In this article, a loading technique for improving pulse radiation from bow-tie antennas is introduced, which makes use of a combination of a constant resistive loading along the antenna and a capacitive loading with linearly increasing reactance toward the antenna ends.
Abstract: In this paper, a loading technique for improving pulse radiation from bow-tie antennas is introduced. This technique allows transmission of short transient pulses with very small late-time ringing and relatively high radiation efficiency. It makes use of a combination of a constant resistive loading along the antenna and a capacitive loading with linearly increasing reactance toward the antenna ends. The constant resistive loading is applied using volumetric microwave absorbers to cover one side of the antenna and the linear capacitive loading is realized by constructing narrow slots on the antenna surface. Relatively high radiation efficiency is achieved by choosing the location of the slot nearest to the feed point in such a way that radiation from it combines constructively with radiation from the feed point. Using a 0.8-ns monocycle for excitation, the technique results in a level of late-time ringing of lower than -40 dB and at the same time the peak value of the transmitted pulse is 54% higher than that of the same antenna without loading.
TL;DR: In this paper, the aperture's electric field distribution is manipulated to create two fictitious short circuits along the slot, hence creating two additional resonances besides the main one, and the frequencies of these fictitious resonances can be chosen such that the overall bandwidth of the antenna is drastically increased.
Abstract: A technique for designing wideband slot antennas is proposed. By selecting the topology of the microstrip feed network, the aperture's electric field distribution is manipulated to create two fictitious short circuits along the slot, hence creating two additional resonances besides the main one. The frequencies of these fictitious resonances can be chosen such that the overall bandwidth of the antenna is drastically increased. By using this technique, a slot antenna with a 1.8:1 bandwidth ratio is designed and fabricated. The measured results of this antenna show similar radiation patterns at different frequencies in its band of operation. Furthermore, the antenna has a relatively constant gain and, more importantly, it has an excellent polarization purity over the entire bandwidth.
TL;DR: In this paper, a broadband multimode antenna system for multiple-input multiple-output (MIMO) and diversity applications is presented, which is not based on spatial diversity, as usual MIMO systems, but a combination of pattern and polarization diversity.
Abstract: This paper presents broadband multimode antennas for multiple-input multiple-output (MIMO) and diversity applications. The antenna system is not based on spatial diversity, as usual MIMO systems, but on a combination of pattern and polarization diversity. Different modes of self-complementary, thus extremely broadband, spiral and sinuous antennas are used to decorrelate the signals. It is shown that only one antenna is necessary to receive three uncorrelated signals, thus the space required to place the MIMO antenna is very small. Simulation results and measurements of a typical indoor scenario are given.
TL;DR: In this paper, a dual broadband rectangular slot antenna for 2.4 and 5 GHz wireless local area network (WLAN) is proposed, which uses a U-shaped strip inset at the center of the rectangular antenna.
Abstract: A novel dual broadband rectangular slot antenna for 2.4 and 5 GHz wireless local area network (WLAN) is proposed. With the use of a U-shaped strip inset at the centre of the rectangular slot antenna, the obtained impedance bandwidths for two operating bands can reach about 10.6% for the 2.4 GHz band and 33.8% for the 5 GHz band, which cover the required bandwidths of IEEE 802.11b/g (2.4-2.484 GHz) and IEEE 802.11a (5.150-5.950 GHz). Details of the antenna design and experimental results are presented and discussed.
TL;DR: The meshed patch offers a complex tradeoff between parameters but gives opportunities for improving the bandwidth and reducing the cross polarization and the antenna dimensions at the expense of the gain.
Abstract: Conventional microstrip patch antennas are printed with continuous solid copper shapes and ground planes. The general properties of meshed patches are presented in this paper where both the patch itself and the ground plane are meshed. The gain, cross-polarization, bandwidth and radiation patterns are discussed for different combinations of patch and ground plane. The radiation patterns are not significantly affected by meshing the patch alone, but meshing the ground plane increases the back radiation. The gain can suffer by up to 3 dB or more when compared to a standard patch. Cross-polarization is improved providing that the correct mesh line geometry is chosen for the excitation mode. Meshing lowered the resonant frequency in some cases by up to 30% and also improves the bandwidth by a factor of up to 2.5 in some modes. Overall, the meshed patch offers a complex tradeoff between parameters but gives opportunities for improving the bandwidth and reducing the cross polarization and the antenna dimensions at the expense of the gain.
TL;DR: In this article, a double resonant antenna with series inductive elements along the radiating section is presented, where the inductive loads are constructed by two balanced short circuited slot lines placed on opposite sides of the slot.
Abstract: In this paper, new methods for further reducing the size and/or increasing the bandwidth (BW) of a class of miniaturized slot antennas are presented. This paper examines techniques such as parasitic coupling and inductive loading to achieve higher BW and further size reduction for this class of miniaturized slot antennas. The overall BW of a proposed double resonant antenna is shown to be increased by more than 94% compared with a single resonant antenna occupying the same area. The behavior of miniaturized slot antennas, loaded with series inductive elements along the radiating section is also examined. The inductive loads are constructed by two balanced short circuited slot lines placed on opposite sides of the radiating slot. These inductive loads can considerably reduce the antenna size at its resonance. Prototypes of a double resonant antenna at 850 MHz and inductively loaded miniaturized antennas at around 1 GHz are designed and tested. Finally the application of both methods in a dual band miniaturized antenna is presented. In all cases measured and simulated results show excellent agreement.
TL;DR: A study of conventional antennas and why they are not suitable for a UWB system is described.
Abstract: Ultra wideband antennas are specifically designed to transmit and/or receive very short time durations of electromagnetic energy. It is well known that UWB antenna design remains the major factor in the progress of UWB technology. This article describes a study of conventional antennas and why they are not suitable for a UWB system.
TL;DR: In this paper, a coplanar waveguide-fed capacitive folded-slot antenna is proposed for the radio frequency identification (RFID) application at 5.8 GHz, where the antenna is fabricated on a 30×30 mm substrate.
Abstract: A coplanar waveguide (CPW)-fed capacitive folded-slot antenna is proposed for the radio frequency identification (RFID) application at 5.8 GHz. The antenna is fabricated on a 30×30 mm substrate. The measured bandwidth and antenna gain are 7.5% and 4.2 dBi, respectively. Radiation patterns are almost omnidirectional in the H-plane. These properties and the compact and uniplanar structure make the antennas suitable for use as RFID tags.
TL;DR: In this paper, the authors confirm the heating characteristics of the coaxial-slot antennas with two slots from a viewpoint of clinical use, and introduce the results of two clinical trials.
Abstract: In recent years, various types of applications of electromagnetic techniques to microwave thermal therapies have been developed. The authors have been studying the coaxial-slot antenna, which is one of the thin microwave antennas, for the minimally invasive microwave thermal therapies, such as interstitial microwave hyperthermia. From the results of our previous studies, it was clear that the coaxial-slot antenna with two slots generates a localized heating region only around the tip of the antenna. In this paper, we confirm the heating characteristics of the coaxial-slot antennas with two slots from a viewpoint of clinical use, and introduce the results of two clinical trials.
15 Nov 2004
TL;DR: In this article, a microstrip antenna incorporating a V-shape slot on its patch is introduced and studied for its impedance bandwidth and radiation characteristics, and the effect of all its parameters, such as the substrate dielectric constant and thickness as well as the V-slot length, position, width and angle, are determined and discussed.
Abstract: A microstrip antenna incorporating a V-shape slot on its patch is introduced and studied for its impedance bandwidth and radiation characteristics. It is shown that the antenna is inherently broadband, and by optimising the V-parameters its performance can be improved considerably over that of a U-slotted patch. Its stacked configuration is also investigated, using both a conducting patch and another V-slotted patch. Bandwidths as high as 54% are achieved with stable pattern characteristics, such as gain and cross polarisation, within its bandwidth. A detailed investigation is conducted and the effect of all its parameters, such as the substrate dielectric constant and thickness as well as the V-slot length, position, width and angle, are determined and discussed. An experimental study confirms the simulation studies.
TL;DR: In this article, a circularly polarized shorted annular ring-slot rectenna (rectifying antenna) on a 0.5 mm thick flexible microwave laminate is proposed for the powering of portable devices operating without batteries.
Abstract: Portable devices operating without batteries are sometimes desired in wireless applications such as RFID (Radio Frequency Identification) and telemetry. A novel circularly polarized shorted annular ring-slot rectenna (rectifying antenna) on a 0.5 mm thick flexible microwave laminate is proposed for the powering of these devices. Output dc voltage of 1.3 V and axial ratio of 1.5 dB were measured when 32 dBm microwave power was transmitted at 5.8 GHz over a distance of 2 m. Comparing the results with a rectenna designed on a thick rigid laminate, similar performance was observed.
TL;DR: In this paper, the performance properties of several electrically small, self-resonant wire antennas are compared as a function of their total wire length, geometry, and effective volume.
Abstract: The performance properties of several electrically small, self-resonant wire antennas are compared as a function of their total wire length, geometry, and effective volume. The radiation properties considered include resonant frequency, radiation resistance, and quality factor (Q). It is shown that the resonant properties of these antennas are directly a function of the antenna's effective height and effective volume, which are established by both total wire length and geometry. When the total wire length and geometry of these antennas are configured such that the antennas exhibit the same effective height and volume, their resonant properties are essentially identical, independent of any differences in their total wire length and geometry. Both computed and measured data are presented to support the comparison of the antennas' resonant properties.
TL;DR: In this paper, a single-feed circularly polarised (CP) microstrip antenna with relaxed manufacturing tolerances is presented, where a cross slot embedded on the radiating patch is used to increase the slot length ratio of the cross slot.
Abstract: A compact design of a single-feed circularly polarised (CP) microstrip antenna with relaxed manufacturing tolerances is presented. The CP operation of the microstrip antenna is achieved using a cross slot embedded on the radiating patch. By cutting an additional cross slot on the ground plane, not only the CP operating frequency can be decreased but also the slot-length ratio of the cross slot on the radiating patch can be considerably increased. In addition, the performance of the proposed design, such as CP bandwidth and peak gain, have no significant reduction.
TL;DR: In this paper, a hybrid structure consisting of a DRA, a circular slot and an eccentric ring slot on a co-plane ground plane is proposed to achieve dual-frequency operation.
Abstract: To achieve dual-frequency operation, a new design concept that utilizes a hybrid structure that includes a dielectric resonator antenna (DRA) and a slot radiating resonator was investigated experimentally. The proposed structure consists of a DRA, a circular slot and an eccentric ring slot on a co-plane ground plane. This arrangement can be described as two cascaded resonant circuits that resonate at two different frequencies. One is from the DRA and the other from the ring slot. Based on the proposed design concept, a number of phototypes have been successfully designed, fabricated and tested. The measured results have demonstrated the validity of the proposed design.
TL;DR: In this paper, the design procedure of a coplanar waveguide (CPW) fed hybrid slot antenna (HSA) having impedance bandwidths up to 57% is described, and the theoretical and measured results are shown.
Abstract: In microwave and millimeter wave applications, slot antennas fed by coplanar waveguide (CPW) lines are receiving increasing attention. These antennas have several useful properties, such as a wider impedance bandwidth compared to microstrip patch antennas, and easier integration of solid-state active devices. In this paper novel CPW-fed wideband slot antennas are presented. The design procedure of CPW-fed hybrid slot antennas (HSA) having impedance bandwidths (VSWR<2) up to 57% is described. Theoretical and measured results are shown. We also describe the design procedure of a CPW-fed log-periodic slot antenna (LPSA). The impedance matching and the radiation characteristics of these structures were studied using a method of moment technique. Simulated and measured results for different dielectrics are presented.
TL;DR: In this article, a full-wave mathematical model is developed and numerical results are presented for the reflection angle for the normally incident circularly polarized wave can be effectively controlled by proper positioning of reactive loads in ring slot resonators.
Abstract: Reflective periodic arrays based on loaded ring slot resonators are analyzed. A full-wave mathematical model is developed and numerical results are presented. It is proven that the reflection angle for the normally incident circularly polarized wave can be effectively controlled by proper positioning of reactive loads in ring slot resonators. Analysis of the reflection characteristics of the Ka band one-layer reflectarray results in a conclusion that the incident wave can be effectively redirected in the directions determined by elevation angles as high as 65/spl deg/ with conversion coefficient better than -1.5 dB. It is also shown that the usage of the multilayer reflectarray leads to a considerable improvement in the reflection characteristics when it is compared with the one-layer reflectarray. The method of the waveguide simulator has been used to verify the developed mathematical model.
TL;DR: In this article, the authors introduce a design methodology for miniature multiband and reconfigurable antennas that exploit the self-similar branching structure of 3D fractal trees, where either reactive LC traps or RF switches are strategically placed throughout the branches and/or along the trunk of the trees.
Abstract: This paper introduces a design methodology for miniature multiband as well as reconfigurable (i.e., tunable) antennas that exploits the self-similar branching structure of three-dimensional (3-D) fractal trees. Several fundamental relationships, useful for design purposes, are established between the geometrical structure of the fractal tree antenna and its corresponding radiation characteristics. In particular, it will be shown that the density and elevation angle of the branches play a key role in the effective design of miniature 3-D fractal tree antennas. Several design examples are considered where fractal trees are used as end-loads in order to miniaturize conventional dipole or monopole antennas. Multiband and reconfigurable versions of these miniature antennas are also proposed, where either reactive LC traps or RF switches are strategically placed throughout the branches and/or along the trunk of the trees. Included among these designs is a miniature reconfigurable dipole antenna that achieves a 57% size reduction for the center frequency of the lowest intended band of operation and has a tunable bandwidth of nearly 70%.
TL;DR: In this paper, single and dual-slot antennas are described, which operate at 10 GHz and 5 GHz, respectively, and they are integrated on microwave laminate, and single-and dual-slotted.
Abstract: Waveguide slot antennas integrated on microwave laminate are presented, and single and dual slot antennas are described, which operate at 10 GHz.
01 Aug 2004
TL;DR: In this article, a planar volcano-smoke slot antenna (PVSA) is proposed for wideband wireless communication applications, which has an appearance reminiscent of a volcanic crater and a puff of smoke.
Abstract: The paper presents a wideband antenna design, referred to as the planar volcano-smoke slot antenna (PVSA), useful for wideband wireless communication applications. The antenna is a planar slot – with an appearance reminiscent of a volcanic crater and a puff of smoke – and is fed by a coplanar waveguide (CPW) to achieve the wide bandwidth. A coax-to-CPW transition, which is crucial for achieving wide bandwidth performance, is modelled and introduced into the antenna, and the impedance, pattern bandwidths and radiation patterns of the antenna are investigated. It is demonstrated that the PVSA has an impedance bandwidth between 0.8 and 6.7 GHz (for a VSWR <2.3) and a pattern bandwidth ranging from 0.8 GHz to 2.0 GHz for the radiation in the upper hemisphere. Finally, an absorber-backed PVSA is designed to suppress the radiation along the side- and back-directions. A front/back (F/B) ratio of better than 15dB has been achieved over the band with an absorbing enclosure backed by a PEC plate.
TL;DR: It is found that the operation of smart antennas on SAR has a significant impact, with SAR changing by over 50% for various signal phases, which leads to the conclusion that if smart antennas are to be utilized in handsets careful investigation of their impact on SAR is needed.
Abstract: We investigate the impact of smart antennas on specific absorption rates (SAR) at 1.9 GHz. We emulate the operation of the smart antennas by utilizing a mobile telephone prototype configured with two PIFA antennas and applying carriers with different signal phases to them. The SAR of this prototype is simulated using FDTD and is also experimentally determined using a MapSAR system. It is found that the operation of smart antennas on SAR has a significant impact, with SAR changing by over 50% for various signal phases. This leads to the conclusion that if smart antennas are to be utilized in handsets careful investigation of their impact on SAR is needed.