Showing papers on "Patch antenna published in 2003"

Printed double-T monopole antenna for 2.4/5.2 GHz dual-band WLAN operations

Abstract: A novel and simple printed dual-band double-T monopole antenna is proposed. The antenna comprises two stacked T-shaped monopoles of different sizes, which generate two separate resonant modes for the desired dual-band operation. The proposed antenna has a low profile and can easily be fed by using a 50 /spl Omega/ microstrip line. Prototypes of the proposed antenna designed for WLAN operations in the 2.4 and 5.2 GHz bands have been constructed and tested. Good radiation characteristics of the proposed antenna have been obtained. Effects of varying the monopole dimensions and the ground-plane size on the antenna performance have also been studied.

Analysis and design of broad-band single-layer rectangular U-slot microstrip patch antennas

Abstract: A wide operating bandwidth for a single-layer coaxially fed rectangular microstrip patch antenna can be obtained by cutting a U-shaped slot on the patch. This antenna structure has recently been found experimentally to provide impedance bandwidths of 10%-40%, even with nonair substrates. However, design rules for this antenna have not yet been presented. This paper develops principle design procedures through examination of the structure's multiple resonant frequencies as well as the radiation and impedance properties of different antenna geometries. The approximate design rules are derived by analysis of former experiments, method of moments (MoM) simulations, and measurement results. Simulations and measurements of several antennas designed using these new rules are presented and directions for further study are discussed.

Broadband design of three-layer printed reflectarrays

Abstract: A method is proposed to design three-layer printed reflectarrays with patches of variable size for broadband operation. The patch dimensions are adjusted by an optimization routine to achieve the required phase distribution in a given frequency band. A 1-meter reflectarray was designed, and significant bandwidth and gain stability improvements were obtained.

Planar artificial magnetic conductors and patch antennas

Abstract: Surfaces act as perfect magnetic conductors (PMC) if the phase shift of the reflection of an electromagnetic wave amounts to 180/spl deg/ compared to the reflection at a perfect electric conductor (PEC). One possibility to create PMC surfaces artificially is an array of closely spaced patches. In this paper, based on the relation between PMC surfaces and patch antennas, an explanation for the functioning of this artificial PMC is given. An equivalent network is derived that allows to understand the functioning and to provide a starting design for a numerical optimization by aid of fullwave methods. A planar PMC is used for the first time as a reflector for a large aperture coupled patch antenna array, especially in order to reduce the parallel-plate modes that are usually present in traditional aperture coupled patch arrays. An additional sidelobe suppression of over 6 dB has been achieved by the planar PMC reflector in comparison to a traditional reflector.

Ground plane effects on planar inverted-F antenna (PIFA) performance

Abstract: The planar inverted-F antenna (PIFA) is popular for portable wireless devices because of its compact size and low profile. The PIFA is designed to operate with a ground plane and the ground plane is an integral part of the antenna assembly. In fact, the ground plane size is the limiting factor for the PIFA in many applications. Some work has been reported on the performance of PIFAs mounted on a conducting box of fixed size; however, what is lacking is a parametric study on the antenna behaviour as a function of geometry or antenna position and orientation on a finite ground plane. The paper presents results from a comprehensive investigation on the performance of a conventional PIFA mounted on ground planes of various sizes and shapes. The orientation and position of the antenna on a fixed-size ground plane is analysed. The influence of ground plane geometry on resonant frequency, bandwidth, gain, and radiation patterns are presented. These results are very useful in the design of a PIFA for applications requiring a small ground plane. Specifically, the results show the trade-offs between PIFA geometry and ground plane size with electrical performance. Both numerical simulation and experimental data are presented.

A low-profile planar monopole antenna for multiband operation of mobile handsets

Abstract: A novel planar monopole antenna is proposed. It has a very low profile (antenna height less than 0.04 times the operating wavelength in free space) and is capable of multiband operation. The proposed antenna has a planar rectangular radiating patch in which a folded slit is inserted at the patch's bottom edge. The folded slit separates the rectangular patch into two subpatches, one smaller inner subpatch encircled by the larger outer one. The proposed antenna is then operated with the inner subpatch resonating as a quarter-wavelength structure and the outer one resonating as both a quarter-wavelength and a half-wavelength structure. The proposed antenna, 12 mm high and 30 mm wide, has been constructed, and the obtained bandwidths cover the global system for mobile communication (890-960 MHz), digital communication system (1710-1880 MHz), personal communication system (1850-1990 MHz), and universal mobile telecommunication system (1920-2170 MHz) bands. Details of the proposed design and obtained experimental results are presented and discussed.

Microstrip antenna for an identification appliance

Abstract: An identification appliance (10), such as a wristband, bracelet, patch, headband, necklace, card, sticker, or other wearable appliance, has an improved patch or microstrip antenna (30). The microstrip antenna comprises a conductive patch layer (22), a conductive ground layer (24) and a dielectric layer (26) in between the conductive layers. The microstrip antenna is mounted to or disposed in the identification appliance, where preferably the ground layer is closest to the user and the patch layer is furthest from the user. Electronic circuits (32) may be located in the dielectric layer, on a surface of a conductive layer, or on another part of the identification appliance. Connecting holes (40) through the dielectric layer may allow circuits to be connected to a conductive layer or layers. This improved antenna resolves detuning and communication degradation problems.

A novel radiation pattern and frequency reconfigurable single turn square spiral microstrip antenna

Abstract: This paper presents a novel pattern and frequency reconfigurable microstrip antenna that uses switched connections. The basic antenna operates with linear polarization around 3.7 GHz. One set of connections provides a re-directed radiation pattern while maintaining a common operating impedance bandwidth with the baseline configuration. The second set of connections results in operation at a higher frequency band at 6 GHz with broadside patterns. Measured results of the three antenna configurations are provided. Potential applications of this reconfigurability and directions for future work are discussed.

A broad-band dual-polarized microstrip patch antenna with aperture coupling

Abstract: In this communication, a dual-polarized aperture-coupled microstrip patch antenna with a broad-bandwidth high-isolation low cross-polarization levels, and low-backward radiation levels is designed and its features are presented. For broad bandwidth and easy integration with active circuits, it uses the aperture-coupled stacked patches. The corner feeding of square microstrip patches is applied and the coupling aperture is the H-shaped aperture. The theoretical analysis is based on the finite-difference time-domain (FDTD) method. A dual-polarized antenna is designed, fabricated, and measured. The measured return loss exhibits an impedance bandwidth of over 24.4% and the isolation is better than 30 dB over the bandwidth. The cross-polarization levels in both E and H planes are better than -23 dB. The front-to-back ratio of the antenna radiation pattern is better than 22 dB. Both theoretical and experimental results for S parameters and radiation patterns are presented and discussed.

A novel approach for miniaturization of slot antennas

Abstract: With the virtual enforcement of the required boundary condition (BC) at the end of a slot antenna, the area occupied by the resonant antenna can be reduced. To achieve the required virtual BC, the two short circuits at the end of the resonant slot are replaced by some reactive BC, including inductive or capacitive loadings. The application of these loads is shown to reduce the size of the resonant slot antenna for a given resonant frequency without imposing any stringent condition on the impedance matching of the antenna. A procedure for designing this class of slot antennas for any arbitrary size is presented. The procedure is based on an equivalent circuit model for the antenna and its feed structure. The corresponding equivalent circuit parameters are extracted using a full-wave forward model in conjunction with a genetic algorithm optimizer. These parameters are employed to find a proper matching network so that a perfect match to a 50 /spl Omega/ line is obtained. For a prototype slot antenna with approximate dimensions of 0.05/spl lambda//sub 0//spl times/0.05/spl lambda//sub 0/ the impedance match is obtained, with a fairly high gain of -3dBi, for a very small ground plane (/spl ap/0.20/spl lambda//sub 0/). Since there are neither polarization nor mismatch losses, the antenna efficiency is limited only by the dielectric and ohmic losses.

Design of small-size wide-bandwidth microstrip-patch antennas

Abstract: Several designs for small-size wide-bandwidth microstrip antennas are examined through simulation and experiment. Designs are presented based on two wideband patch antennas: the U-slot patch antenna, and the L-probe-fed patch antenna. Several techniques are utilized to reduce the resonant length of these wideband microstrip-patch antennas: increasing the dielectric constant of the microwave substrate material, the addition of a shorting wall between the conducting patch and the ground plane, and the addition of a shorting pin between the conducting patch and the ground plane. Simulation and experimental results confirm that the size of the antennas can be reduced by as much as 94%, while maintaining impedance bandwidths in excess of 20%.

A dual polarized aperture coupled circular patch antenna using a C-shaped coupling slot

Abstract: The design and development of a dual linearly polarized aperture coupled circular microstrip patch antenna at C-band are presented. The antenna uses a novel configuration of symmetric and asymmetric coupling slots. Variations in isolation between orthogonal feedlines and antenna axial ratio with the position of coupling slots are studied and broadband isolation and axial ratio are achieved. The prototype antenna yields 7.6 dBi peak gain, 70/spl deg/ 3-dB beam width, 25 dB cross-polarization levels and an isolation better than 28 dB between the two ports. With an external quadrature hybrid coupler connected to the two orthogonal feedlines, the antenna yields 3-dB axial ratio bandwidth of more than 30% at 5.8 GHz.

A broad-band CPW-fed strip-loaded square slot antenna

Abstract: A novel broadband design of a coplanar waveguide fed square slot antenna loaded with conducting strips is proposed and experimentally studied. The obtained results show that the impedance bandwidth, determined by 10-dB return loss, of the proposed slot antenna can be greater than 60%. The design considerations for achieving broad-band operation of the proposed slot antenna are described, and experimental results are presented.

Dual-polarized slot-coupled planar antenna with wide bandwidth

Abstract: A new dual-polarized slot-coupled microstrip patch antenna is presented, which can achieve high-isolation, low cross-polarization levels, a wide bandwidth, and low backward radiation levels. The coupling slot is an H-shaped slot. For wide bandwidth and easy integration with active circuits, it uses slot-coupled stacked microstrip patches. The theoretical analysis is based on the finite-difference time-domain (FDTD) method. First, a parametric study on the input impedance of the antenna with a single input port is presented. Based on the results, a dual-polarized microstrip antenna is designed, fabricated, and then measured. The measured return loss exhibits an impedance bandwidth of over 20.9% and the isolation between two polarization ports is better than 36 dB over the bandwidth. The cross-polarization levels in both E and H planes are better than 22 dB. The front-to-back ratio of the antenna radiation pattern is better than 21 dB. Both theoretical and experimental results of return loss, isolation, and radiation patterns are presented and discussed.

An experimental coin-sized radio for extremely low-power WPAN (IEEE 802.15.4) application at 2.4 GHz

Abstract: An experimental 2.4-GHz CMOS radio composed of RF and digital circuits for the low-power and low-rate preliminary IEEE802.15.4 WPAN is reported, consuming 21 mW in receive mode and 30 mW in transmit mode. The RF design focus is to maximize linearity for a given power consumption using linearization methods which lead an order of magnitude improvement in LNA/mixer IIP3/power performance. Chip-on-PCB technology allows implementation of a coin-sized radio at very low cost, which also provides 3 dBi gain patch antenna and high Q (>50) inductors.

Low-cost broadband circularly polarized patch antenna

Abstract: A novel single-feed broadband circularly polarized patch antenna is proposed. The proposed antenna has a simple structure, consisting of a corner-truncated square radiating patch, an L-shaped ground plane, and a probe feed. Through a via hole in the vertical ground of the L-shaped ground plane, the radiating patch is easily excited by a probe feed oriented in the same plane as the patch, and circular polarization (CP) radiation over a wide frequency range (>10%) is achieved. Experimental results of a constructed prototype with the center operating frequency at about 2500 MHz showed that the antenna has an impedance bandwidth (1.5:1 VSWR) of about 30%, a 3-dB axial-ratio CP bandwidth of about 10.4%, and a gain level of 8.5 dBi or larger within the CP bandwidth. In addition to the low cost of the proposed antenna due to its simple structure, the obtained CP performance is among the best that have been reported for single-feed single-element patch antennas.

Numerical and experimental investigation of an ultrawideband ridged pyramidal horn antenna with curved launching plane for pulse radiation

Abstract: We report the numerical analysis and experimental characterization of an ultrawideband (UWB) antenna designed for radiating short microwave pulses. The antenna consists of a pyramidal horn, a ridge, and a curved launching plane terminated with resistors. The pyramidal horn is connected to the outer conductor of the coaxial feed and serves as the ground plane. The curved launching plane is connected to the central conductor of the coaxial feed. Detailed three-dimensional finite-difference time-domain (FDTD) simulations have been conducted to assist with the characterization of the antenna. FDTD results are compared with experimental data and are shown to be in good agreement. We demonstrate that the antenna exhibits a very low voltage standing wave ratio (/spl les/1.5) over a wide frequency range from 1 to 11 GHz and a very high fidelity (/spl ges/0.92). The spatial distribution of radiated energy is characterized both in the time domain, using transient field observations at various angles, as well as in the frequency domain, using single-frequency far-field radiation patterns. We conclude that this antenna offers high-fidelity transmission and reception of ultrashort microwave pulses with minimal distortion.

Topology design optimization of dielectric substrates for bandwidth improvement of a patch antenna

Abstract: Most literature studies dealing with design optimization for RF applications focused to a large extend on size and shape optimization So far, material and topology optimization has not been pursued primarily due to the challenges associated with the fabrication of inhomogeneous materials and the limited access to analysis tools In this paper, we focus on optimum topology/material design of dielectric substrates for bandwidth enhancement of a simple patch antenna First, the possibility of designing arbitrary dielectric constant materials using off-the-shelf dielectrics is presented as is necessary for the practical fabrication of inhomogeneous substrates Then, a formal design optimization procedure is conducted using the solid isotropic material with penalization (SIMP) method by relying on a fast full wave finite element-boundary integral (FE-BI) simulator The SIMP method is a mathematically well-posed topology optimization algorithm because a continuous density function is used to relate the cell variable to the actual material properties This also allows for a formulation in a versatile optimization framework Sequential linear programming (SLP) is used to solve the nonlinear optimization procedure with the sensitivity analysis based on the adjoint variable method An important advantage of the proposed design optimization approach is its generality to handle multiple objectives and multidisciplinary problems Using the proposed automated design procedure, inhomogeneous substrates are designed which allow for 250% bandwidth enhancement of the square patch antenna Typically, only a few iterations are needed to reach convergence Finally, the designed substrate is post-processed with image processing and fabricated using thermoplastic green machining

Planar antenna with supplemental antenna current configuration arranged between dominant current paths

Abstract: An antenna arrangement is described in which a pair of at least generally planar opposing antenna arms each support a first high frequency antenna current responsive to an input Each arm includes a peripheral outline for confining the first high frequency current to a pair of first and second dominant paths, that are defined by the peripheral outline, in a spaced apart relationship across each of the opposing antenna arms so as to define an isolated area between the first and second paths A configuration is located in this area of at least one of the antenna arms for producing an additional high frequency current responsive to the input The additional high frequency current cooperates with the first high frequency antenna current to produce an overall antenna response In one feature, the opposing antenna arms are bow arms which cooperate to define an overall bow-tie configuration as the peripheral outline

A novel fabric WLAN antenna for wearable applications

Abstract: The development of wearable computer systems and smart clothing has been rapid. They are coming more and more lightweight and quite soon we will see a wide range of unobtrusive wearable and ubiquitous computing equipment integrated to into our everyday wear. Rapid progress in wireless communication promises to replace wired-communication networks in the near future in which antennas have a more important role. This paper presents a novel fabric WLAN antenna for wearable applications such as sports wear and emergency worker outfits. The substrate of the patch antenna is made of a very low-cost fleece fabric. The radiating element and groundplane are made of knitted copper. To our best knowledge this is the first compact fabric antenna design for commercial smart clothing. Measured results are compared with simulations and good agreement was observed.

Radio frequency identification tagging

Abstract: A RFID tag or label comprises a RFID tag module (comprising an electronic identification circuit and a coupling means) and an antenna structure coupled to the coupling means. The RFID tag module is separate from, separable or arranged to be severable from, the antenna structure. The tag module can be placed in or on an object and the antenna structure in or on packaging material for use with the object. A patch antenna type RFID tag antenna structure has a ground plane spaced from the patch antenna so as to increase the range of the tag. The ground plane is not substantially larger than, and electrically insulated from, the patch antenna. The ground plane is flexible, so the RFID tag structure can be worn by a human, and can be incorporated into a piece of clothing. A RFID antenna structure for use with a tag reader is made flat and robust so that it can be mounted on the ground to be walked upon or driven over. A bi-directional YAGI type RFID tag antenna structure has director elements on two opposite sides so that the YAGI antenna radiates in two opposite directions. An object includes a gain increasing metallic structure for increasing the gain of a RFID tag when placed near the object so as to form a RFID tag antenna structure.

Circularly-polarized-wave patch antenna which can be used in a wide frequency band

Abstract: A circularly-polarized-wave patch antenna includes a main body having a patch electrode provided with two feeding points and a circuit for generating a phase difference of 90° between signals supplied to the feeding points. A Wilkinson distribution circuit is provided between the 90°-phase-difference generating circuit and a coaxial cable (feeder line) so as to improve a reflection characteristic. The patch antenna includes two feeding points, and thus a favorable axial ratio characteristic can be obtained in a wide band. Also, a favorable reflection characteristic can be obtained in a wide band because of the Wilkinson distribution circuit. Accordingly, the patch antenna can be used in a wider frequency band.

Harmonics reduction with defected ground structure for a microstrip patch antenna

Abstract: A microstrip patch antenna using a defected ground structure (DGS) to suppress higher order harmonics is presented. An H-shaped defect on the ground plane with only one or more unit lattices has been utilized and yielded bandstop characteristics. Compared with a conventional microstrip patch antenna without the DGS unit cell, the radiated power of the DGS patch antenna at harmonic frequencies has been drastically decreased.

Wearable microstrip antenna

Abstract: Microstrip antennas are being used as a representative antenna for mobile and satellite communication The microstrip antennas have features such as planarity and a relatively high gain (about 7 dBi) It is typical to fabricate them by using hard substrates However, these substrates are limited in shape and mounting placement for fixing such an antenna to clothing or hats Therefore, we created a flexible and light-weight antenna The antenna we built is composed of a flexible woven conductive fabric and felt Because of the construction, it can be easily sewn into clothing or hats It can be applied as a GPS antenna for monitoring the position of wandering aged, or as a terminal antenna for personal satellite communications In this paper, the structure of the antenna is described, and its characteristics are evaluated

On the behavior of Koch island fractal boundary microstrip patch antenna

Abstract: The properties of the Koch island fractal boundary microstrip patch antenna are presented. The behavior at the fundamental mode and the existence of high-order modes that exhibit localized current density distributions is discussed. The main features are the size reduction of the patch resonating at the fundamental frequency when compared to Euclidean-shaped patches, and the application of localized modes in designing microstrip patch antennas with directive patterns.

Extendable planar diversity antenna

Abstract: The present invention is a retractable/extendable diversity antenna that provides the appropriate polarization in a horizontal orientation. The antenna structure is placed within a Type II PCMCIA PC card package and may be extended or retracted with one touch. The antenna structure is large enough to provide for the diversity antenna design and may optionally be housed within a PCMCIA Type II PC Card. At least one spring-loaded mechanism is used to extend the antenna structure beyond the PCMCIA PC Card package and to provide stability while the antenna structure is in the extended position. The diversity antenna configuration may consist of either two miniature, planar antenna modules or two etched printed circuit board contours that are spaced as far apart as possible with a minimum separation of a quarter wave length distance in order to provide mitigation to radio multipath fading effects. The antenna modules have orientations perpendicular to each other such that the polar nulls representative of their radiation patterns remain spatially orthogonal.

Multiband planar built-in radio antenna with inverted-l main and parasitic radiators

Abstract: A multi-band radio antenna device (1) for a radio communication terminal, comprising a flat ground substrate (20), a flat main radiating element (2, 9) having a radio signal feeding point (3), and a flat parasitic element (5, 6). The main radiating 5 element is located adjacent to and in the same plane as said ground substrate, and preferably dielectrically separated therefrom. The antenna device is suitable for being used as a built-in antenna in portable radio terminals, such as a mobile phone (30).

Antenna device, radio reception device, and radio transmission device

Abstract: There are provided an antenna deice, a signal reception device, and a signal transmission device utilizing an antenna element having a microstrip structure and coplanar structure and using a superconductive material. The antenna device, the signal reception device, and the signal transmission device realize improvement of a directivity gain, reduction of size, and reduction of power consumption. The antenna device includes: a planar antenna element; an adiabatic vessel having a radio window for transmitting electric waves, containing the planar antenna element, and insulating heat from outside; a waveguide arranged in the adiabatic vessel between the radio window and the antenna pattern formation plane of the planar antenna element; and cooling means for cooling the planar antenna element. The waveguide has a shape and dimensions which intensify the directivity of the planar antenna element and a superconductive film is used for the antenna pattern of the planar antenna element.

A systematic design method to obtain broadband characteristics for singly-fed electromagnetically coupled patch antennas for circular polarization

Abstract: We present a systematic, empirical design technique to obtain optimum broadband impedance, axial-ratio (AR) and gain bandwidths for a singly-fed electromagnetically coupled patch antenna for circular polarization. Our investigation has also revealed tradeoffs amongst obtainable AR, impedance bandwidth and AR bandwidth. Using two design examples at different frequency bands and for different senses of circular polarization, we have demonstrated the effectiveness of the proposed knowledge-based tuning method. We have obtained at C-band measured values of impedance bandwidth (VSWR/spl les/2) equal to 43%, 3-dB AR bandwidth of 8%, AR of less than 0.3 dB and a mean gain level of 7 dB. For the Ku-band element, a 40% impedance bandwidth and a 17.3% of 3-dB AR bandwidth have been obtained with a peak gain of 7.2 dBic.

Wide band four-port butler matrix for switched multibeam antenna arrays

Abstract: This paper presents the design and realization of a wide band four-port microstrip matrix to feed a switched-beam antenna array for wireless applications at 1.9 GHz. The objective of this investigation is to develop an antenna-array feeding network based on Butler with a large bandwidth in order to cover the PCS band: 1900 MHZ to 2200 MHZ. In order to meet these requirements, wide band microwave components such as hybrids and crossovers were designed and used to Butler proposed matrix. The Butler matrix is used as a beamforming network that allows to produce orthogonal beams that can be steered in different directions. To examine the performance of the proposed matrix, simulated and experimental results is presented and discussed.