Showing papers on "Slot antenna published in 2012"
TL;DR: A printed two-multiple-input multiple-output (MIMO)-antenna system incorporating a neutralization line for antenna port decoupling for wireless USB-dongle applications is proposed and it was found that the antenna port isolation can be effectively improved by removing only 1.5 mm long inwards from the top edge in the small ground portion.
Abstract: A printed two-multiple-input multiple-output (MIMO)-antenna system incorporating a neutralization line for antenna port decoupling for wireless USB-dongle applications is proposed. The two monopoles are located on the two opposite corners of the system PCB and spaced apart by a small ground portion, which serves as a layout area for antenna feeding network and connectors for the use of standalone antennas as an optional scheme. It was found that by removing only 1.5 mm long inwards from the top edge in the small ground portion and connecting the two antennas therein with a thin printed line, the antenna port isolation can be effectively improved. The neutralization line in this study occupies very little board space, and the design requires no conventional modification to the ground plane for mitigating mutual coupling. The behavior of the neutralization line was rigorously analyzed, and the MIMO characteristics of the proposed antennas was also studied and tested in the reverberation chamber. Details of the constructed prototype are described and discussed in this paper.
363 citations
TL;DR: In this article, the theoretical performance limit for small antenna performance has been validated by all available experimental evidence and the theoretical predictions for the performance due to design factors such as permittivity, aspect ratio, and the internal structure of the antenna are also supported by the experimental evidence.
Abstract: The theoretical limit for small antenna performance that was derived decades ago by Wheeler and Chu governs design tradeoffs for size, bandwidth, and efficiency. Theoretical guidelines have also been derived for other details of small antenna design such as permittivity, aspect ratio, and even the nature of the internal structure of the antenna. In this paper, we extract and analyze experimental performance data from a large body of published designs to establish several facts that have not previously been demonstrated: (1) The theoretical performance limit for size, bandwidth, and efficiency are validated by all available experimental evidence. (2) Although derived for electrically small antennas, the same theoretical limit is also generally a good design rule for antennas that are not electrically small. (3) The theoretical predictions for the performance due to design factors such as permittivity, aspect ratio, and the internal structure of the antenna are also supported by the experimental evidence. The designs that have the highest performance are those that involve the lowest permittivity, have an aspect ratio close to unity, and for which the fields fill the minimum size enclosing sphere with the greatest uniformity. This work thus validates the established theoretical design guidelines.
255 citations
TL;DR: In this paper, a low-profile substrate integrated waveguide (SIW) cavity-backed slot antenna is presented, where two hybrid modes, whose dominant fields are located in different half parts of the SIW cavity are two different combinations of the and resonances.
Abstract: A bandwidth enhanced method of a low-profile substrate integrated waveguide (SIW) cavity-backed slot antenna is presented in this paper. Bandwidth enhancement is achieved by simultaneously exciting two hybrid modes in the SIW-backed cavity and merging them within the required frequency range. These two hybrid modes, whose dominant fields are located in different half parts of the SIW cavity, are two different combinations of the and resonances. This design method has been validated by experiments. Compared with those of a previously presented SIW cavity-backed slot antenna, fractional impedance bandwidth of the proposed antenna is enhanced from 1.4% to 6.3%, its gain and radiation efficiency are also slightly improved to 6.0 dBi and 90%, and its SIW cavity size is reduced about 30%. The proposed antenna exhibits low cross polarization level and high front to back ratio. It still retains advantages of low-profile, low fabrication cost, and easy integration with planar circuits.
254 citations
01 Oct 2012
TL;DR: In this article, a lens-based antenna with a solid dielectric ellipsoid PTFE lens for industrial tank level probing radar (TLPR) is presented, which achieves a high gain of 25.9 dBi with a beamwidth of ≈ 8.4° at an outer diameter of 74mm.
Abstract: A lens-based antenna with a solid dielectric ellipsoid PTFE lens for industrial tank level probing radar (TLPR) is presented. Due to limitations of the application, a high antenna gain at a limited size as well as a good matching were the main design goals. The presented antenna achieves a high gain of 25.9 dBi with a beamwidth of ≈ 8.4° at an outer diameter of 74mm in simulations, which is confirmed by measurements. Despite the lens surface reflections, a good input matching of ≈ −20 dB is achieved in the full wide frequency band from 23 GHz to 28 GHz, which enables monostatic radar operation even close to the antenna. A laboratory radar setup is used to confirm the accuracy impact on distance measurements in a scenario with disturbing reflectors.
205 citations
TL;DR: Simulation and experimental results are used to substantiate the effectiveness of the proposed design approach on a two-monopole array with an antenna spacing of 0.1 wavelength, and to demonstrate the underlying decoupling mechanism for two arbitrary antennas.
Abstract: Compact arrays such as multiple antennas on a mobile terminal suffer from low efficiency and high correlation between antenna signals. In the present paper, a simple and rigorous procedure for decoupling two closely coupled antennas with a parasitic scatterer is proposed. The parasitic scatterer, which can be an additional antenna, acts as a shield between two active antenna elements. In contrast to previous studies involving the use of parasitic scatterer for decoupling antennas, we demonstrate using antenna impedances the underlying decoupling mechanism for two arbitrary antennas. By a proper choice of parameters, perfect matching and decoupling can be obtained for a given antenna spacing without extending the overall area used, and without introducing additional decoupling networks. The price to pay is a reduction of bandwidth relative to that of widely spaced antennas, which is the case for other decoupling methods as well. Simulation and experimental results are used to substantiate the effectiveness of the proposed design approach on a two-monopole array with an antenna spacing of 0.1 wavelength. Finally, several practical considerations of the proposal are also presented, including the extension of the approach for more than two active antennas and its implementation in mobile terminals.
203 citations
TL;DR: In this paper, a new compact pattern reconfigurable U-slot antenna is presented, which can operate in either monopolar patch or normal patch mode in similar frequency ranges, and its radiation pattern can be switched between conical and boresight patterns electrically.
Abstract: A new compact pattern reconfigurable U-slot antenna is presented The antenna consists of a U-slot patch and eight shorting posts Each edge of the square patch is connected to two shorting posts via PIN diodes By switching between the different states of the PIN diodes, the proposed antenna can operate in either monopolar patch or normal patch mode in similar frequency ranges Therefore, its radiation pattern can be switched between conical and boresight patterns electrically In addition, the plane with the maximum power level of the conical pattern can be changed between two orthogonal planes Owing to a novel design of the switch geometry, the antenna does not need dc bias lines The measured overlapping impedance bandwidth (|S11| <; -10 dB) of the two modes is 66% with a center frequency of 532 GHz The measured radiation patterns agree well with simulated results The antennas are incorporated in a 2 × 2 multiple-input-multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) system to demonstrate the improvement in system capacity In the real-time MIMO-OFDM channel measurement, it is shown that compared to omnidirectional antennas, the pattern reconfigurable antennas can enhance the system capacity, with 17% improvement in a line-of-sight (LOS) scenario and 12% in a non-LOS (NLOS) scenario at a signal-to-noise ratio (SNR) of 10 dB
198 citations
06 Mar 2012
TL;DR: General antenna concepts, partly including some system aspects, as well as three realized antenna configurations will be described in detail in this contribution.
Abstract: Automotive radars are on the market since 1999, both in the frequency range around 24 GHz as well as 76.5 GHz, with a new frequency band ranging from 77 to 81 GHz intended for medium and short-range sensors. The choice and design of the respective sensor antennas are determined by the requirement for high gain and low loss combined with small size and depth for vehicle integration, the challenges by the millimeter-wave frequency range, and a great cost pressure for this commercial application. Consequently, planar antennas are dominating in the lower frequency range, while lens and reflector antennas had been the first choice at 76.5 GHz, partly in folded configurations. With increasing requirements towards a much more detailed observation of the scenery in front or around the vehicle, multibeam antennas or scanning antennas have been designed, and solutions based on (digital) beamforming with a number of integrated antennas are in use or under development. General antenna concepts, partly including some system aspects, as well as three realized antenna configurations will be described in detail in this contribution.
198 citations
TL;DR: In this paper, a closely packed ultrawideband (UWB) multiple-input multiple-output (MIMO)/diversity antenna (of two elements) with a size of 25 mm by 40 mm is proposed for USB dongle applications.
Abstract: A closely-packed ultrawideband (UWB) multiple- input multiple-output (MIMO)/diversity antenna (of two elements) with a size of 25 mm by 40 mm is proposed for USB dongle applications. Wideband isolation can be achieved through the different patterns and polarizations of the two antenna elements. Moreover, the slot that is formed between the monopole and the ground plane of the half slot antenna is conveniently used to further enhance the isolation at the lower frequencies and to provide an additional resonance at one antenna element in order to increase its bandwidth. The underlying mechanisms of the antenna's wide impedance bandwidth and low mutual coupling are analyzed in detail. Based on the measurement results, the proposed antenna can cover the lower UWB band of 3.1-5.15 GHz, and within the required band, the isolation exceeds 26 dB. The gains and total efficiencies of the two antenna elements are also measured. Furthermore, a chassis mode can be excited when a physical connection is required between the ground planes of the two antenna elements. Without affecting the performance of the half slot element, the monopole can now cover the band of 1.78-3 GHz, apart from the UWB band. The proposed antenna structure is found to provide good MIMO/diversity performance, with very low envelope correlation of less than 0.1 across the UWB band.
178 citations
TL;DR: In this article, a printed wide-slot antenna with a parasitic patch for bandwidth enhancement is proposed and experimentally investigated, which exhibits a wide impedance bandwidth, which is over 80% for |S11| ≤ -10 dB ranging from 2.23 to 5.35 GHz.
Abstract: A printed wide-slot antenna with a parasitic patch for bandwidth enhancement is proposed and experimentally investigated. A simple 50-Ω microstrip line is used to excite the slot. A rotated square slot resonator is considered as reference geometry. The rotated square slot antenna exhibits two resonances (f1 : lower resonant frequency, f2: higher resonant frequency). By embedding a parasitic patch into the center of the rotated square slot, the lower resonant frequency is decreased and the higher resonant frequency is increased. Thus, broadband characteristic of the wide-slot antenna is achieved. The measured results demonstrate that this structure exhibits a wide impedance bandwidth, which is over 80% for |S11| ≤ -10 dB ranging from 2.23 to 5.35 GHz. Also, a stable and omnidirectional radiation pattern is observed within the operating bandwidth. In this design, a smaller ground plane is considered compared to the reference antenna (rotated square slot antenna without the parasitic center patch).
172 citations
TL;DR: In this article, a reconfigurable wideband and multiband C-slot patch antenna with dual-patch elements is proposed and studied, where two parallel C-Slots on the patch elements are employed to perturb the surface current paths for excitation of the dual-band and wideband modes.
Abstract: A reconfigurable wideband and multiband C-Slot patch antenna with dual-patch elements is proposed and studied. It occupies a compact volume of 50 × 50 × 1.57 (3925 mm3), including the ground plane. The antenna can operate in two dual-band modes and a wideband mode from 5 to 7 GHz. Two parallel C-Slots on the patch elements are employed to perturb the surface current paths for excitation of the dual-band and the wideband modes. Two switches, implemented using PIN diodes, are placed on the connecting lines of a simple feed network to the patch elements. Dual-band modes are achieved by switching “ON” either one of the two patch elements, while the wideband mode with an impedance bandwidth of 33.52% is obtained by switching “ON” both patch elements. The frequencies in the dual-band modes can be independently controlled using positions and dimensions of the C-Slots without affecting the wideband mode. The advantage of the proposed antenna is that two dual-band operations and one wideband operation can be achieved using the same dimensions. This overcomes the need for increasing the surface area normally incurred when designing wideband patch antennas. Simulation results are validated experimentally through prototypes. The measured radiation patterns and peak gains show stable responses and are in good agreements. Coupling between the two patch elements plays a major role for achieving the wide bandwidth and the effects of mutual coupling between the patch elements are also studied.
172 citations
Patent•
03 Aug 2012
TL;DR: In this paper, a circularly polarized waveguide slot array includes first and second waveguide sections, the first waveguide section extending along a longitudinal axis, and including an antenna element for transmitting or receiving a cyclically polarized signal.
Abstract: A circularly polarized waveguide slot array includes first and second waveguide sections, the first waveguide section extending along a longitudinal axis, and including an antenna element for transmitting or receiving a circularly polarized signal. The second waveguide slot section is coupled side-to-side with the first waveguide slot section and extends along the longitudinal axis, the second waveguide slot section including an antenna element for transmitting or receiving the circularly polarized signal at a phase which is substantially complementary to the circularly polarized signal transmitted by or received by the first waveguide slot section. Further exemplary, the antenna element disposed on the first waveguide slot section is offset from said antenna element disposed on the second waveguide slot section substantially one half of a predefined guide wavelength λg along said longitudinal axis.
Patent•
17 Jul 2012TL;DR: An electromagnetic-radiation power-supply mechanism includes a microwave power introduction port provided on the side of the coaxial waveguide and a power supply antenna for radiating the electromagnetic wave power into the waveguide as mentioned in this paper.
Abstract: An electromagnetic-radiation power-supply mechanism includes a microwave power introduction port provided on the side of the coaxial waveguide, a power line being connected to the microwave power introduction port; and a power supply antenna for radiating the electromagnetic wave power into the waveguide, the power supply antenna being connected to the power line. The power supply antenna includes an antenna body having a first pole connected to the power line and a second pole connected to an inner conductor of the waveguide; and a ring-shaped reflection portion extending from opposite sides of the antenna body.
Patent•
19 Dec 2012TL;DR: In this paper, a surface wave plasma source (SWPS) was proposed, having an electromagnetic (EM) wave launcher including a slot antenna configured to couple EM energy in a desired EM wave mode to a plasma.
Abstract: A surface wave plasma source (SWPS) is disclosed, having an electromagnetic (EM) wave launcher including a slot antenna configured to couple EM energy in a desired EM wave mode to a plasma by generating a surface wave on a plasma surface of the SWPS adjacent the plasma. The SWPS also includes a dielectric window positioned below the slot antenna, having a lower surface and the plasma surface. The SWPS further includes an attenuation assembly disposed between the slot antenna and the plasma surface. The attenuation assembly includes a first fluid channel substantially aligned with a first arrangement of slots in the slot antenna, and is configured to receive a first flow of a first fluid at a first fluid temperature. The SWPS finally includes a power coupling system coupled to the EM wave launcher and configured to provide EM energy to the EM wave launcher for forming the plasma.
TL;DR: In this article, a compact cross-shaped slotted microstrip patch antenna is proposed for circularly polarized (CP) radiation, where a symmetric, cross shaped slot is embedded along one of the diagonal axes of the square patch for CP radiation and antenna size reduction.
Abstract: A compact cross-shaped slotted microstrip patch antenna is proposed for circularly polarized (CP) radiation. A symmetric, cross shaped slot is embedded along one of the diagonal axes of the square patch for CP radiation and antenna size reduction. The structure is asymmetric (unbalanced) along the diagonal axes. The overall size of the antenna with CP radiation can be reduced by increasing the perimeter of the symmetric cross-shaped slot within the first patch quadrant of the square patch. The performance of the CP radiation is also studied by varying the size and angle variation of the cross-shaped slot. A measured 3-dB axial-ratio (AR) bandwidth of around 6.0 MHz is achieved with the CP cross-shaped slotted microstrip antenna, with an 18.0 MHz 10-dB return-loss bandwidth. The measured boresight gain is more than 3.8 dBic over the operating band, while the overall antenna volume is 0.273λo × 0.273λo × 0.013λo (λο operating wavelength at 910 MHz).
TL;DR: In this paper, a wide slot antenna backed by a substrate integrated waveguide (SIW) cavity is presented and investigated for the enhancement of operating bandwidth at 60 GHz band, and the measured results show that the antenna array with slot WLR of 0.71 achieves the gain of 10-12 dBi and the cross-polarization levels of better than 25 dB in both E- and H-planes.
Abstract: A wide slot antenna backed by a substrate integrated waveguide (SIW) cavity is presented and investigated for the enhancement of operating bandwidth at 60-GHz band. The 10-dB return loss impedance bandwidth of the antenna increases from 3% to 11.6% with consistent radiation performance as the width to length ratio (WLR) of the rectangular slot cutting from the SIW increases from 0.12 to 0.71. Its dual-resonance operation mechanism is verified by a parametric study. Three 2 × 4 antenna arrays with different slot WLRs are designed and fabricated with a printed circuit board (PCB) process at the 60-GHz bands. The measured results show that the antenna array with slot WLR of 0.71 achieves the gain of 10-12 dBi and the cross-polarization levels of better than 25 dB in both E- and H-planes over the enhanced operating bandwidth of about 11.6%.
TL;DR: Measurements performed on the antenna after bending and integration into clothing indicate high robustness against deformation and low influence of the human body on antenna performance, making the design well-suited for on-body use.
Abstract: A novel wearable substrate integrated waveguide antenna fabricated entirely from textile materials is presented. The cavity-backed slot antenna operates in the 2.45 GHz industrial, scientific and medical band, for short range communication between rescue workers. A prototype of the antenna was fabricated and tested: good performance was obtained in terms of input matching and radiation pattern. Moreover, measurements performed on the antenna after bending and integration into clothing indicate high robustness against deformation and low influence of the human body on antenna performance, making the design well-suited for on-body use.
TL;DR: In this article, a low-profile antenna consisting of an octagonal-shaped slot fed by a beveled and stepped rectangular patch for covering the UWB band (3.1-10.6 GHz) was presented.
Abstract: A novel compact ultrawideband (UWB) printed slot antenna with three extra bands for various wireless applications is presented. The low-profile antenna consists of an octagonal-shaped slot fed by a beveled and stepped rectangular patch for covering the UWB band (3.1-10.6 GHz). By attaching three inverted U-shaped strips at the upper part of the slot in the ground, additional triple linear polarized bands can be realized covering GPS (1520-1590 MHz), part of GSM (1770-1840 MHz), and Bluetooth (2385-2490 MHz). Simulated and measured results are presented and compared, which shows that the antenna has a stable radiation pattern both at the triple and the whole of the UWB bands.
Patent•
04 Apr 2012
TL;DR: In this paper, an antenna for a medical device, e.g., an implantable medical device (IMD), comprises an electrically conductive wire that spirals to form a three-dimensional shape of a rectangular cuboid.
Abstract: In an embodiment, an antenna for a medical device, e.g., an implantable medical device (IMD), comprises an electrically conductive wire that spirals to form a three-dimensional shape of a rectangular cuboid. In another embodiment, the antenna comprises an electrically conductive wire that spirals to form a three-dimensional shape of an elliptical cylinder, an oval cylinder, an elongated pentagonal prism, an elongated hexagonal prism, or some other shape where the longitudinal diameter of the antenna is greater than the lateral diameter of the antenna. The antennas are sized to fit within a portion of a header of the medical device. Such antennas are designed to provide increased antenna gain and antenna bandwidth.
TL;DR: In this paper, the authors investigated the underlying physics of two popular circularly polarized microstrip patch antennas, namely U-slot and E-shaped patches, for achieving better performance and axial ratio (AR) and cross-polarization performance.
Abstract: Characteristic mode (CM) analysis is carried out to understand the underlying physics of two popular circularly polarized (CP) microstrip patch antennas, namely U-slot and E-shaped CP patch antennas, for achieving better performance. Modifications of these two CP antennas with optimal feed position and compact patch size are explicitly obtained through examining the CMs, modal significance, and characteristic angle. Compared to conventional designs, the two modified designs have better axial ratio (AR) and cross-polarization performance without introducing any additional design cost or complexity. It is also interesting to find that: 1) offset probe feed in CP U-slot patch antennas will provide excellent AR performance; 2) cutting off the redundant section from CP E-shaped patch antenna will yield low cross polarization and more compact configuration.
TL;DR: In this paper, a tri-band printed antenna for WLAN and WiMAX applications is presented, which consists of a modified rectangular slot, a pair of symmetrical inverted-L strips, and a Y-shaped monopole radiator with a meandering split-ring slot.
Abstract: A novel compact tri-band printed antenna for WLAN and WiMAX applications is presented. The proposed antenna consists of a modified rectangular slot, a pair of symmetrical inverted-L strips, and a Y-shaped monopole radiator with a meandering split-ring slot. Tuning the locations and the sizes of these structures, three distinct current paths can be produced at three independent frequency bands, respectively. Based on this concept, a prototype of the tri-band antenna is further fabricated and measured. The experimental and numerical results show that the antenna has impedance bandwidth (for return loss less than 10 dB) of 430 MHz (2.33-2.76 GHz), 730 MHz (3.05-3.88 GHz), and 310 MHz (5.57-5.88 GHz), which can cover both the WLAN 2.4/5.8-GHz bands and the WiMAX 2.5/3.5-GHz bands.
TL;DR: In this article, a frequency-reconfigurable microstrip slot antenna is proposed, which is capable of frequency switching at six different frequency bands between 2.2 and 4.75 GHz.
Abstract: A frequency-reconfigurable microstrip slot antenna is proposed. The antenna is capable of frequency switching at six different frequency bands between 2.2 and 4.75 GHz. Five RF p-i-n diode switches are positioned in the slot to achieve frequency reconfigurability. The feed line and the slot are bended to reduce 33% of the original size of the antenna. The biasing circuit is integrated into the ground plane to minimize the parasitic effects toward the performance of the antenna. Simulated and measured results are used to demonstrate the performance of the antenna. The simulated and measured return losses, together with the radiation patterns, are presented and compared.
TL;DR: In this article, a circularly polarized (CP) cavity-backed annular slot antenna for GPS receiver is designed to operate in both the L1 and L2 bands of the Global Positioning System (GPS).
Abstract: A circularly polarized (CP) cavity-backed annular slot antenna for GPS receiver is designed to operate in both the L1 and L2 bands of the Global Positioning System (GPS). The measured impedance bandwidths with VSWR less than 2 are 3.7% (1.19-1.235 GHz) and 1.2% (1.565-1.585 GHz), respectively, the measured 3 dB axial-ratio (AR) bandwidth are 0.9% (1.220-1.231 GHz) and 0.6% (1.572-1.581 GHz), respectively. A cavity is designed to render a unidirectional radiation pattern.
TL;DR: In this paper, a novel technique for the bandwidth enhancement of a cavity-backed slot antenna is presented, where a via-hole located above the slot creates an additional resonance at a higher frequency by shortening the effective length of the slot.
Abstract: A novel technique for the bandwidth enhancement of a cavity-backed slot antenna is presented. A via-hole located above the slot creates an additional resonance at a higher frequency by shortening the effective length of the slot. The location of the via-hole can be changed to determine the second resonance frequency of the antenna. With proper placement of the via-hole, the bandwidth of cavity-backed slot antenna can be increased. The fabricated antenna has a 60% wider bandwidth than a cavity-backed slot antenna without a via-hole. The proposed antenna maintains high radiation efficiency and gain, which are characteristics of a conventional cavity-backed slot antenna. The proposed technique is especially useful for enhancing the bandwidth of a cavity-backed slot antenna in a limited area.
TL;DR: In this article, a simple design for circularly-polarized (CP) annular slot antennas is presented, where the antenna is fed by a V-shaped coupling strip loaded with a small resistance.
Abstract: A simple design for circularly-polarized (CP) annular slot antennas is first described. The antenna is fed by a V-shaped coupling strip loaded with a small resistance, and it can generate CP radiation as long as the inclined angle of the V-shaped coupling strip is properly adjusted. Numerical analyses to the effects of varying the angle on CP axial ratio are performed. Several CP prototypes are fabricated. Both simulated and measured results demonstrate that the proposed feeding mechanism can give good CP performances for the case that the slot width is varied from 0.008 to 0.09 λ0. Then, a design for polarization reconfigurable antennas is developed from the feeding mechanism. Only two PIN diodes are involved in the reconfigurable design that can offer the switching among three different polarizations, including one linear polarization and dual orthogonal circular polarizations. Details of the designs and experimental results are shown.
TL;DR: In this paper, a novel printed reconfigurable square slot antenna with switchable band-notched and multiresonance performances is designed and manufactured, which exhibits good radiation behavior within the ultrawideband (UWB) frequency range.
Abstract: A novel printed reconfigurable square slot antenna with switchable band-notched and multiresonance performances is designed and manufactured. In the proposed structure, in order to generate single band-notched characteristics, a Π-shaped slot is etched on the radiating stub. Furthermore, to achieve a reconfigurable function, a p-i-n diode is utilized across the slot. When this p-i-n diode is biased forwardly, the Π -shaped slot transforms to a pair of C-shaped slots, and also by changing to this new structure, an additional resonance is excited. Additionally, by cutting two modified L-shaped slits with variable dimensions on the microstrip feed line, new additional resonance is excited, and hence wider impedance bandwidth can be produced, especially at the higher band. The designed antenna has a small size of 20 × 20 mm2 while showing the radiation performance in the frequency band of 3.04 to over 11.17 GHz with a switchable band-rejection performance in the frequency band of 5.03-5.94 GHz. Simulated and experimental results obtained for this antenna show that it exhibits good radiation behavior within the ultrawideband (UWB) frequency range and also it has a reconfigurable frequency band-notched function in the range of 5-6 GHz that can eliminate the interference between UWB frequency band and other existing wireless communication systems.
Abstract: A low profile coplanar waveguide (CPW) fed printed slot antenna is presented with uni-directional radiation properties. The slot antenna radiates above a closely spaced artificial magnetic conducting (AMC) reflector consisting of an array of rectangular patches, a substrate and an electric ground plane. The electromagnetic bandgap (EBG) performance of the cavity structure between the upper conducting surface in which the slot is etched, and the ground plane at the bottom of the reflector, is investigated using an equivalent waveguide feed in the place of a half-wavelength section of the slot antenna. From the reflection coefficient of the equivalent waveguide feed one can determine the frequency band where minimum energy will be lost due to unwanted radiation from the cavity sides. The dimensions of the cavity were found to be very important for minimum energy loss. Experimental results for the final antenna design (with a size of 1.02λ0×0.82λ0×0.063λ0), mounted on a 1.5λ0×1.5λ0 back plate, exhibit a 5% impedance bandwidth, maximum gain in excess of 10 dBi, low cross-polarization, and a front-to-back ratio of approximately 25 dB. This low-profile antenna with relatively high gain could be a good candidate for a 2.4 GHz WLAN application.
TL;DR: In this article, a planar slot antenna array operating at 140 GHz band is presented and implemented using a low-temperature co-fired ceramic (LTCC) process, which comprises a substrate integrated waveguide (SIW) feeding network and slot radiators with a dielectric loading.
Abstract: A planar slot antenna array operating at 140-GHz band is presented and implemented using a low-temperature co-fired ceramic (LTCC) process. The array comprises a substrate integrated waveguide (SIW) feeding network and slot radiators with a dielectric loading. Considerations associated with the 140-GHz design and the effects of the dielectric loading on antenna performance are investigated. Measured results show that the boresight gain of a 4 t 4 antenna array including a transition from SIW to a waveguide is 16.3 dBi at 140 GHz and higher than 13.8 dBi over the operating bandwidth of 130-152 GHz. Therefore, the LTCC process offers one more option of planar broadband antenna array designs operating at upper millimeter wave bands.
TL;DR: In this paper, a planar metamaterial unit cell with an interdigital capacitor and a complementary split-ring resonator (CSRR) slot was proposed to achieve high efficiency and reasonable gain.
Abstract: A wideband patch antenna loaded with a planar metamaterial unit cell is proposed. The metamaterial unit cell is composed of an interdigital capacitor and a complementary split-ring resonator (CSRR) slot. A dispersion analysis of the metamaterial unit cell reveals that an increase in series capacitance can decrease the half-wavelength resonance frequency, thus reducing the electrical size of the proposed antenna. In addition, circulating current distributions around the CSRR slot with increased interdigital finger length bring about the TM01 mode radiation, while the normal radiation mode is the TM10 mode. Furthermore, the TM01 mode can be combined with the TM10 mode without a pattern distortion. The hybridization of the two modes yields a wideband property (6.8%) and a unique radiation pattern that is comparable with two independent dipole antennas positioned orthogonally. Also, the proposed antenna achieves high efficiency (96%) and reasonable gain (3.85 dBi), even though the electrical size of the antenna is only 0.24λ0×0.24λ0×0.02λ0.
TL;DR: In this article, a U-slot tri-band monopole antenna on a low-cost paper substrate using inkjet-printed technology is presented for the first time, which can be used to cover the GPS, WiMAX, HiperLAN/2, and WLAN.
Abstract: Realization of a U-slot tri-band monopole antenna on a low-cost paper substrate using inkjet-printed technology is presented for the first time. The U-shaped slot is optimized to enhance the bandwidth and to achieve tri-band operation of 1.57, 3.2, and 5 GHz with measured impedance bandwidths of 3.21%, 28.1%, and 36%, respectively. The antenna is fabricated through a metallic nanoparticle ink on a standard commercial paper. Thus, the antenna can be used to cover the GPS, WiMAX, HiperLAN/2, and WLAN. The antenna has a compact size of 12 × 37.3 × 0.44 mm3, leaving enough space for the driving electronics on the paper substrate. The impedance bandwidth, current distributions, radiation patterns, gain, and efficiency of the antenna have been studied through computer simulations and measurements.
TL;DR: In this paper, an annular slot antenna suitable for pattern diversity in wideband applications is presented, where two shorts placed at 45 degrees between the microstrip lines and in the opposite direction ensure an isolation above 15 dB according to measurements.
Abstract: An annular slot antenna suitable for pattern diversity in wideband applications is presented. Pattern diversity is obtained by feeding the antenna simultaneously with two microstrip lines printed on the back of the substrate, which generate orthogonal radiation patterns. Two shorts placed at 45 degrees between the microstrip lines and in the opposite direction ensure an isolation above 15 dB according to measurements. The antenna operates in the range of frequencies from 3 GHz to 12 GHz (1:4 bandwidth) and covers many different standards (Wireless-LAN, HIPERLAN2, WIMAX, UWB). Simulations and measurements for return loss, isolation and radiation patterns are presented. Furthermore, measurements have been carried out in a real multipath environment in order to evaluate pattern diversity performance. Results of measurements of the correlation coefficient and diversity gain over the entire operating bandwidth show that the antenna is suitable for antenna diversity systems.