Showing papers on "Slot antenna published in 2009"

Optical antenna thermal emitters

Abstract: Optical antennas are a critical component in nanophotonics research1 and have been used to enhance nonlinear2,3 and Raman4 cross-sections and to make nanoscale optical probes5. In addition to their ‘receiving’ properties, optical antennas can operate in ‘broadcasting’ mode, and have been used to modify the emission rate6 and direction7 of individual molecules. In these applications the antenna must operate at frequencies given by existing light emitters. Using thermal excitation of optical antennas, we bypass this limitation and realize emitters at infrared frequencies where sources are less readily available. Specifically, we show that the thermal emission from a single SiC whisker antenna is attributable to well-defined, size-tunable Mie resonances8. Furthermore, we derive a fundamental limit on the antenna emittance and argue theoretically that these structures are nearly ideal black-body antennas. Combined with advancing progress in antenna design, these results could lead to optical antenna emitters operating throughout the infrared frequency range. Single SiC whiskers can be made into infrared emitters by thermal excitation. The broadband thermal emission is coupled to the electromagnetic resonances of the whisker, allowing relatively narrowband emission at infrared frequencies. The emission frequency can be tuned by adjusting the size of the whiskers.

Development of Low Profile Cavity Backed Crossed Slot Antennas for Planar Integration

Abstract: Single fed low profile cavity backed crossed slot antennas for dual frequency dual linear polarization and circular polarization applications are first presented in this paper. By employing the substrate integrated waveguide (SIW) technique in the antenna designs, the low profile backed cavity structure can be realized by using only a single layer of low cost printed circuit board (PCB) substrate. A single grounded coplanar waveguide (GCPW) is employed as the feeding element to excite the TE 120 and TE 210 modes in the SIW cavity. A crossed slot structure is used as the radiating element in order to radiate the desired dual linearly or circularly polarized wave. From the measurement results, it is seen that these novel antennas retain the advantages of conventional metallic cavity backed antennas, including high gain, high front-to-back ratio (FTBR), and low cross polarization level (CPL). Furthermore, the proposed antennas also possess the advantages of low profile, light weight, low fabrication cost, and easy integration with planar circuits.

Performances of an Implanted Cavity Slot Antenna Embedded in the Human Arm

Abstract: Implantable devices have been investigated with great interest as communication tools. These implantable devices are embedded into the human or pet body. The vital information (such as temperature, blood pressure, cardiac beat, etc.) can be transmitted from implantable devices to the external equipment by use of a wireless communication link. Therefore, the research on the antenna for implantable devices (implanted antennas) is very important. This paper proposes an implanted H-shaped cavity slot antenna for short-range wireless communications. This type of antenna, which is designed to operate at the industrial-scientific-medical band (2.45 GHz), is investigated by using finite-difference time-domain calculation. We analyzed the performances of the proposed antenna which is embedded into the human body between the shoulder and the elbow. However, since the proposed antenna is too small to fabricate, a scale model is adopted for antenna measurements. Some characteristics of the scale model of the antenna are also calculated and measured by using the 2/3 muscle-equivalent phantom. The results show that the proposed antenna has promise for use in an implant.

Bandwidth Enhancement of a Microstrip-Line-Fed Printed Wide-Slot Antenna With a Fractal-Shaped Slot

Abstract: Microstrip-line-fed printed wide-slot antenna with a fractal-shaped slot for bandwidth enhancement is proposed and experimentally studied. By etching the wide slot as fractal shapes, it is experimentally found that the operating bandwidth can be significantly enhanced, and the relation between the bandwidth and the iteration order (IO) and iteration factor (IF) of the fractal shapes is experimentally studied. Experimental results indicate that the impedance bandwidth, defined by - 10 dB reflection coefficient, of the proposed fractal slot antenna can reach an operating bandwidth of 2.4 GHz at operating frequencies around 4 GHz, which is about 3.5 times that of a conventional microstrip-line-fed printed wide-slot antenna. It also achieved a 2-dB gain bandwidth of at least 1.59 GHz.

Transient Characteristics of Wearable Antennas and Radio Propagation Channels for Ultrawideband Body-Centric Wireless Communications

Abstract: This paper presents transient characterization of ultrawideband (UWB) body-worn antennas and on-body radio propagation channels for body-centric wireless communications. A novel miniaturized CPW-fed tapered slot antenna is proposed and used for transient measurements of UWB radio channels for body area network (BAN) and personal area network (PAN) scenarios. Unlike conventional UWB CPW-fed antennas, the proposed antenna employs two diverging tapered slots to provide smooth and stable impedance matching. Fidelity analysis is applied to evaluate the time-domain behavior of body-worn antennas and it is found that average fidelity obtained is 88% and 86% for the conventional coplanar waveguide fed antenna and the tapered slot antenna, respectively. However, the tapered slot antenna shows a significant size reduction and hence is suited for body-centric wireless communications.

Flat Screen With Integrated Antenna

Abstract: The invention relates to a flat screen (E) that comprises an active pixel matrix (M), an electrode that is common to said pixels (C), and a conductive strip (R) preferably in the form of a ring that is connected to said common electrode and at least partially surrounds said active matrix, characterised in that at least one slot (F) defining an antenna is formed in said conducting strip. The invention also relates to a portable apparatus that comprises: such a flat screen (E); an electronic board including a floorplan (PM) parallel to the flat screen and electrically connected to the conductive strip of the same; a means for generating and/or detecting electric radiofrequency signals; and an excitation port (P) for the slot antenna (F) installed in the flat screen, and connected to said means for generating and/or detecting electric radiofrequency signals.

Antenna-in-Package Design for Wirebond Interconnection to Highly Integrated 60-GHz Radios

Abstract: This paper first presents a quasi-cavity-backed, guard-ring-directed, substrate-material-modulated slot antenna. The antenna, intended for use in highly integrated 60-GHz radios, is deliberately designed to exhibit capacitive input impedance to suit low-cost wire-bonding packaging and assembly technique. The antenna implemented in a thin cavity-down ceramic ball grid array (CBGA) package in low-temperature cofired ceramic (LTCC) technology has achieved an acceptable impedance bandwidth from 59 to 65 GHz with an estimated efficiency of 94%. At millimeter-wave (mm-wave) frequency 60 GHz, one of key challenges is how to realize low-loss interconnection between a radio chip and an antenna using wire-bonding technique. This paper then addresses this issue in the framework of antenna-in-package (AiP) design at 60 GHz and proposes a new solution to the challenge. Detailed wirebond design method and results are given. A major concern with AiP is the risk of the antenna coupling to the radio chip. This paper also evaluates this unwanted coupling and shows that the coupling from the in-package antenna to the on-chip inductor is lower than 30 dB for the worst case. These results clearly demonstrate the feasibility and promise of the elegant AiP technology for emerging high-speed short-range 60-GHz wireless communications.

The Analysis of a Reconfigurable Antenna With a Rotating Feed Using Graph Models

Abstract: This letter investigates a new reconfigurable antenna technique based on the rotation of a slot. The surface currents are redistributed for each slot position. The antenna is simulated, fabricated, and tested. The return loss frequency tuning matches the simulated data. The antenna radiation pattern remains unchanged for different slot positions. Finally, the process for automatic rotation and control of the slot is investigated using graph models.

Bandwidth Enhancement of Novel Compact Single and Dual Band-Notched Printed Monopole Antenna With a Pair of L-Shaped Slots

Abstract: A dual band-notched printed ultrawideband monopole antenna is presented, with a modified ground plane. By using this modified element including a pair of variable L-shaped slots, cut in the ground plane, additional resonances are excited and hence the bandwidth is increased up to 130%. To generate single and dual band-notched characteristics, we use inverted U- and fork-shaped parasitic structures, respectively, instead of changing the patch or feedline shapes. By properly adjusting the dimensions of these capacitive-coupled elements, not only one or two controllable notch resonances are achieved, but also the lower-edge frequency of the band is decreased. The measured results show that the proposed dual band-notched monopole antenna offers a very wide bandwidth from 2.2 to 13.4 GHz (143%), defined by 10-dB return loss, with two notched bands, covering all the 5.2/5.8-GHz WLAN, 3.5/5.5-GHz WiMax and 4-GHz C bands. Impedance, radiation, efficiency and gain characteristics of the antenna are also discussed.

Dual-Band Dual-Sense Circularly-Polarized CPW-Fed Slot Antenna With Two Spiral Slots Loaded

Abstract: A novel design of a dual-band dual-sense circularly-polarized CPW-fed slot antenna with two spiral slots loaded is presented. The two loaded spiral slots in the ground plane can result in different senses of circular polarization. The dual-band operation is achieved by using the T-shape strip. The ratio of two frequencies is 1.375. The antenna is designed, fabricated, and measured. It is shown that the proposed antenna has good circular polarization characteristic. The measured 10 dB return loss impedance bandwidths are 8.7% for the lower band (RHCP) and 23% for the upper band (LHCP). The measured 3 dB axial-ratio bandwidths are 8.4% and 19.24%, with respect to 1.6 GHz (RHCP) and 2.2 GHz (LHCP), respectively.

A Novel Compact Ultra-Wideband (UWB) Wide Slot Antenna with via Holes

Abstract: A novel compact ultra-wideband (UWB) wide slot antenna with via holes is presented for UWB applications. The antenna is composed of a trapezoidal slot on the ground plane, a rectangular patch in the center of the slot and three via holes connecting the rectangular patch and the microstrip feed-line. The antenna is successfully designed, implemented, and measured. The measured results show that the proposed antenna with compact size of 27:0mm£29:0mm£1:0mm achieves good performance, such as an impedance matching bandwidth of 111.7% (jS11j • i10dB), constant gain and stable radiation patterns over its whole frequency range.

Characteristics of Cavity Slot Antenna for Body-Area Networks

Abstract: Antennas and the propagation characteristics for body-area networks have become an active area of research. In this paper, a cavity slot antenna is proposed for onbody communications at 2.45 GHz. First, the antenna characteristics (input impedance, radiation pattern, and efficiency) are calculated by the finite-difference time-domain method. The results show that the proposed antenna has a relatively high efficiency of more than 50% even in the vicinity of the human body. Next, the onbody radio wave-propagation characteristics are investigated through numerical simulation and experimental measurements of the electric-field distributions around a phantom with a simplified shape of a human arm. Both sets of results are then compared and discussed. Finally, good agreement between the measured and the calculated results is confirmed.

A Multibeam Antenna Based on Substrate Integrated Waveguide Technology for MIMO Wireless Communications

Abstract: A 24-beams slot array antenna, which achieves 360-degrees coverage over azimuth direction, based on substrate integrated waveguide (SIW) technology is designed, fabricated and measured for supporting the concept of triangle cell, beam diversity and multiple input multiple output (MIMO) wireless communications. Constructed by six 4-beams single layer SIW antennas which integrate the 4times8 modified Butler matrix with a low side lobe level (SLL) amplitude distribution, measured SLLs are reduced as low as -14.5 dB for all beams in E-plane. The size of the SIW single layer multibeam antenna is 385 mm times 110 mm including feeding network. The usable bandwidth of the proposed antenna is 3.75% at 16 GHz.

Substrate Integrated Waveguide (SIW) Monopulse Slot Antenna Array

Abstract: A Ka-band compact single layer substrate integrated waveguide monopulse slot array antenna for the application of monopulse tracking system is designed, fabricated and measured. The feeding network as well as the monopulse comparator and the subarrays is integrated on the same dielectric with the size of 140 mmtimes130 mm. The bandwidth ( S11 < -10 dB) of the antenna is 7.39% with an operating frequency range of 30.80 GHz-33.14 GHz. The maximum gain at 31.5 GHz is 18.74 dB and the maximum null depth is -46.3 dB. The sum- and difference patterns of three planes: H-plane, E-plane and diagonal plane are measured and presented.

Multiband Printed Monopole Slot Antenna for WWAN Operation in the Laptop Computer

Abstract: A multiband printed monopole slot antenna promising for operating as an internal antenna in the thin-profile laptop computer for wireless wide area network (WWAN) operation is presented. The proposed antenna is formed by three monopole slots operated at their quarter-wavelength modes and arranged in a compact planar configuration. A step-shaped microstrip feedline is applied to excite the three monopole slots at their respective optimal feeding position, and two wide operating bands at about 900 and 1900 MHz are obtained for the antenna to cover all the five operating bands of GSM850/900/1800/1900/UMTS for WWAN operation. The antenna is easily printed on a small-size FR4 substrate and shows a length of 60 mm only and a height of 12 mm when mounted at the top edge of the system ground plane or supporting metal frame of the laptop display. Details of the proposed antenna are presented and studied.

Design of UWB Planar Band-Notched Antenna Using Parasitic Elements

Abstract: A method is described to reject certain bands within the passband of an ultrawideband (UWB) planar antenna using parasitic elements. In the presented design, the antenna is created by a planar monopole and a ground plane both of half circle shape, whereas parasitic elements are in the form of printed strips. Four examples of UWB antenna design are shown. The first design is without parasitic, while the remaining ones are with parasitics to reject a single narrow band, a wide band or three narrow bands. The results of simulation and measurements show that all these antenna designs exhibit a 10-dB return loss bandwidth from 3 GHz to 11 GHz excluding the rejected bands. More than 10 dB gain drop is recorded in the suppressed bands. The time domain transmission test between two identical antennas without the parasitic strips shows an almost distortionless pulse performance.

Analysis of Planar Ultrawideband Antennas With On-Ground Slot Band-Notched Structures

Abstract: Planar ultrawideband (UWB) antennas with on-ground band-notched structures are studied in this paper. Two different slot resonators, which feature quarter-wavelength and half-wavelength configurations, are embedded into the arc shaped ground plane of the circular disk patch antennas in order to obtain the desired band-rejection around 5.8 GHz. Their principles and characteristics are analyzed and compared in detail providing designers with in-depth understanding and useful design information. By choosing the quarter-wavelength slot resonator, the first spurious stopband can be pushed up to 3 f 0 (f 0 stands for the center frequency of the notch) and this antenna retains a super wide working band which spans from 1.62 GHz to 17.43 GHz. Performance in both the frequency domain and time domain for this antenna has been investigated carefully. The transmission response of a transceiving antenna system and their corresponding transient analysis are discussed at the end of this paper.

Handheld electronic devices with isolated antennas

Abstract: Handheld electronic devices are provided that contain wireless communications circuitry having at least first and second antennas. An antenna isolation element reduces signal interference between the antennas, so that the antennas may be used in close proximity to each other. A planar ground element may be used as a ground by the first and second antennas. The first antenna may be formed using a hybrid planar-inverted-F and slot arrangement in which a planar resonating element is located above a rectangular slot in the planar ground element. The second antenna may be formed from an L-shaped strip. The planar resonating element of the first antenna may have first and second arms. The first arm may resonate at a common frequency with the second antenna and may serve as the isolation element. The second arm may resonate at approximately the same frequency as the slot portion of the hybrid antenna.

Dielectric Loaded Impedance Matching for Wideband Implanted Antennas

Abstract: In implanted biomedical devices, due to the presence of surrounding dissipative biological tissue, the antenna suffers poor impedance matching. This causes degradation in the performance of a wideband or ultra-wideband (UWB) implanted device. Moreover, the electrical properties of tissue change from organ to organ, and possibly from time to time. In this paper, it is shown that loading of antennas with suitable insulators can deliver broadband matching across a range of dissipative medium properties. An impedance-matched UWB antenna designed to operate inside a lossy medium, which has varying electromagnetic properties within the range expected in biological tissues, is presented. The operating bandwidth of the proposed design is 3.5-4.5 GHz, which is an interference-free subset of the unlicensed UWB band in the US. It is demonstrated that once the dielectric loading is applied, the conventional procedure for antenna design in free space can be followed. The proposed implantable small capsule-shaped slot antenna has been characterized using numerical simulations. Details of a proof-of-concept experiment are presented.

Miniaturized Microstrip-Fed Tapered-Slot Antenna With Ultrawideband Performance

Abstract: A method to design a microstrip-fed antipodal tapered-slot antenna, which has ultrawideband (UWB) performance and miniaturized dimensions, is presented. The proposed method modifies the antenna's structure to establish a direct connection between the microstrip feeder and the radiator. That modification, which removes the need to use any transitions and/or baluns in the feeding structure, is the first step in the proposed miniaturization. In the second step of miniaturization, the radiator and ground plane are corrugated to enable further reduction in the antenna's size without jeopardizing its performance. The simulated and measured results confirm the benefits of the adopted method in reducing the surface area of the antenna, while maintaining the ultrawideband performance.

Single- and Dual-Polarized Tunable Slot-Ring Antennas

Abstract: Single-and dual-polarized slot-ring antennas with wideband tuning using varactor diodes have been demonstrated. The single-polarized antenna tunes from 0.95 to 1.8 GHz with better than -13 dB return loss. Both polarizations of the dual-polarized antenna tune from 0.93 to 1.6 GHz independently with better than -10 dB return loss and > 20 dB port-to-port isolation over most of the tuning range. The capacitance of the varactor diodes varies from 0.45 to 2.5 pF, and the antennas are printed on 70times70 times0.787 mm3 substrates with epsivr = 2.2. The dual-polarized slot-ring antenna can either be made both frequency- and polarization-agile simultaneously, or can operate at two independent frequencies on two orthogonal polarizations. To our knowledge, this is the first dual-polarized tunable antenna with independent control of both polarizations over a 1.7:1 frequency range.

Design of reconfigurable antennas based on an L-shaped slot and PIN diodes for compact wireless devices

Abstract: A basic antenna structure to design pattern and pattern/frequency reconfigurable antennas is proposed. The structure consists of an L-shaped slot, PIN diodes, lumped capacitors and bias networks. The PIN diodes and the lumped capacitors located at specific positions are used to create short circuits across the slot. By carefully controlling these diodes, the induced current distribution around the slot can be changed, resulting in different antenna radiation patterns. Thus, a pattern reconfigurable antenna can be achieved. The proposed structure is then extended to design frequency/pattern reconfigurable antennas by introducing varactor diodes. Two compact reconfigurable antennas based on the proposed structure are designed and implemented to prove the design concepts. The experiment results fully demonstrated the performances of the proposed designs. Owing to the compact size and ease on manufacture, the proposed structure can be a promising solution in compact wireless devices such as smart phones and notebook computers.

79 GHz Slot Antennas Based on Substrate Integrated Waveguides (SIW) in a Flexible Printed Circuit Board

Abstract: The design, fabrication and characterization of 79 GHz slot antennas based on substrate integrated waveguides (SIW) are presented in this paper. All the prototypes are fabricated in a polyimide flex foil using printed circuit board (PCB) fabrication processes. A novel concept is used to minimize the leakage losses of the SIWs at millimeter wave frequencies. Different losses in the SIWs are analyzed. SIW-based single slot antenna, longitudinal and four-by-four slot array antennas are numerically and experimentally studied. Measurements of the antennas show approximately 4.7%, 5.4% and 10.7% impedance bandwidth (S11=-10 dB) with 2.8 dBi, 6.0 dBi and 11.0 dBi maximum antenna gain around 79 GHz, respectively. The measured results are in good agreement with the numerical simulations.

Design and implementation of low sidelobe substrate integrated waveguide longitudinal slot array antennas

Abstract: Low sidelobe longitudinal slot array antennas are investigated based on substrate integrated waveguide (SIW) technology. The design method consists of the characterisation of the radiating element, the synthesis of the linear array and the development of the planar array including a feeding power divider by performing full-wave electromagnetic simulations for the final accurate design. Two planar slot array antennas are fabricated with a normal printed circuit board (PCB) process. Low sidelobe features are verified by the measured results which are in agreement with the simulated results. For an 8 times 8 SIW slot array antenna, the measured sidelobe levels (SLLs) are below -36 dB in the H-plane and below -25 dB in the E-plane with the Gain of 20.3 dB at 9.9 GHz. And for a 16 times 16 antenna, the SLLs are below -30 dB both in the E-plane and H-plane with the Gain of 24.4 dB at 10 GHz. The achieved design goals on the radiation patterns therefore validate the proposed low sidelobe SIW slot array antennas to be valuable candidates for high performance communication and radar applications.

Design of a Compact Semi-Elliptic Monopole Slot Antenna for UWB Systems

Abstract: A printed semi-elliptic monopole slot antenna for use in ultrawideband (UWB) communication systems is presented. The antenna features a coplanar waveguide signal strip terminated with a semi-elliptic stub and a modified ground plane to achieve wide bandwidth from 2.85-20 GHz. An exhaustive study of the radiation characteristics of this antenna in the frequency and time domains are presented. Design equations are derived and experimentally validated. Transient analysis indicates linear phase response and minimum dispersion to the transmitted pulse. The proposed radiator is omnidirectional with appreciable gain throughout the band.

Compact Broadband Slotted Rectangular Microstrip Antenna

Abstract: The broadband and compact rectangular microstrip antenna (MSA) is realized either by cutting a half-U-slot or rectangular slot inside the patch In this letter, broadband rectangular microstrip antenna, by cutting a half-U-slot and rectangular slot on the edges of the patch, is proposed Due to the two resonant slots, the antenna gives more bandwidth as compared to only a rectangular-slot-cut or a half-U-slot-cut rectangular microstrip antenna The proposed antenna has broadside radiation pattern over the entire bandwidth

Compact coplanar waveguide-fed ultra-wideband monopole-like slot antenna

Abstract: A simple and compact coplanar waveguide (CPW)-fed ultra-wideband (UWB) monopole-like slot antenna is presented. The proposed antenna comprises a monopole-like slot and a CPW fork-shaped feeding structure, which is etched onto an FR4 printed circuit board (PCB) with an overall size of 26 mm x 29 mm x 1.5 mm. The simulation and experiment show that the proposed antenna achieves good impedance matching, consistent gain, stable radiation patterns and consistent group delay over an operating bandwidth of 2.7-12.4 GHz (128.5%). Furthermore, through adding two more grounded open-circuited stubs, the proposed antenna design features band-notched characteristic in the band of 5-6 GHz while maintaining the desirable performance over lower/upper UWB bands of 3.1-4.85 GHz/6.2-9.7 GHz.

A Coplanar Reconfigurable Folded Slot Antenna Without Bias Network for WLAN Applications

Abstract: The design of a reconfigurable single folded slot antenna is shown. Metal strips are used in the slot to manipulate the ground size around the slot, which yields to changing the slot's perimeter and thus changing the resonant frequency of the antenna. The design of a single folded slot antenna is first illustrated. Later, the design is modified to be reconfigurable. The resonant frequencies for the reconfigurable design are chosen to be applicable with the WLAN applications. The antenna design, simulation, and measurements are described. The simulated results both for the return loss and maximum gain agree with the measurements. The antenna has similar radiation patterns in both bands. The advantage of this design is that the length of the bias lines does not affect the antenna performance, thus making its design, feeding, and matching an extremely simple and low-cost procedure for antenna designers.

Optical antennas and plasmonics

Abstract: Optical antenna is a nanoscale miniaturisation of radio or microwave antennas that is also governed by the rule of plasmonics. We introduce various types of optical antenna and make an overview of recent developments in optical antenna research. The role of local and surface plasmons in optical antenna is explained through antenna resonance and resonance conditions for specific metal structures are explicitly obtained. A strong electric field is shown to exist within a highly localised region of optical antennas such as antenna feed gap or apertures. We describe physical properties of field enhancement in apertures (circular and rectangular holes) and gaps (infinite slit and feed gap), as well as experimental techniques measuring enhanced electric vector field. We discuss the analogies and differences between conventional and optical antennas with a projection for future developments.

8 Gbit/s wireless data transmission at 250 GHz

Abstract: 8 Gbit/s wireless data transmission using a 250 GHz millimetre-wave carrier signal is demonstrated. Photonic devices and technologies, including an electro-optic modulator and J-band uni-travelling-carrier photodetector (UTC-PD) module, were used for the transmitter. In addition, a high-efficiency Schottky barrier diode detector monolithically integrated with a ring slot antenna was developed and fabricated for the receiver on the same epi-layer as the UTC-PD.