Showing papers on "Microstrip antenna published in 2002"

Compact and Broadband Microstrip Antennas

Abstract: Preface. 1. Introduction and Overview. 1.1 Introduction. 1.2 Compact Microstrip Antennas. 1.3 Compact Broadband Microstrip Antennas. 1.4 Compact Dual-Frequency Microstrip Antennas. 1.5 Compact Dual-Polarized Microstrip Antennas. 1.6 Compact Circularly Polarized Microstrip Antennas. 1.7 Compact Microstrip Antennas with Enhanced Gain. 1.8 Broadband Microstrip Antennas. 1.9 Broadband Dual-Frequency and Dual-Polarized Microstrip Antennas. 1.10 Broadband and Dual-Band Circularly Polarized Microstrip Antennas. 2. Compact Microstrip Antennas. 2.1 Introduction. 2.2 Use of a Shorted Patch with a Thin Dielectric Substrate. 2.3 Use of a Meandered Patch. 2.4 Use of a Meandered Ground Plane. 2.5 Use of a Planar Inverted-L Patch. 2.6 Use of an Inverted U-Shaped or Folded Patch. 3. Compact Broadband Microstrip Antennas. 3.1 Introduction. 3.2 Use of a Shorted Patch with a Thick Air Substrate. 3.3 Use of Stacked Shorted Patches. 3.4 Use of Chip-Resistor and Chip-Capacitor Loading Technique. 3.5 Use of a Slot-Loading Technique. 3.6 Use of a Slotted Ground Plane. 4. Compact Dual-Frequency and Dual-Polarized Microstrip Antennas. 4.1 Introduction. 4.2 Some Recent Advances in Regular-Size Dual-Frequency Designs. 4.3 Compact Dual-Frequency Operation with Same Polarization Planes. 4.4 Compact Dual-Frequency Operation. 4.5 Dual-Band or Triple-Band PIFA. 4.6 Compact Dual-Polarized Designs. 5. Compact Circularly Polarized Microstrip Antennas. 5.1 Introduction. 5.2 Designs with a Cross-Slot of Unequal Arm Lengths. 5.3 Designs with a Y-Shaped Slot of Unequal Arm Lengths. 5.4 Designs with Slits. 5.5 Designs with Spur Lines. 5.6 Designs with Truncated Corners. 5.7 Designs with Peripheral Cuts. 5.8 Designs with a Tuning Stub. 5.9 Designs with a Bent Tuning Stub. 5.10 Compact CP Designs with an Inset Microstrip-Line Feed. 6. Compact Microstrip Antennas with Enhanced Gain. 6.1 Introduction. 6.2 Compact Microstrip Antennas with High-Permittivity Superstrate. 6.3 Compact Microstrip Antennas with Active Circuitry. 7. Broadband Microstrip Antennas. 7.1 Introduction. 7.2 Use of Additional Microstrip Resonators. 7.3 Microstrip Antennas with an Air Substrate. 7.4 Broadband Slot-Loaded Microstrip Antennas. 7.5 Broadband Microstrip Antennas with an Integrated Reactive Loading. 7.6 Broadband Microstrip Antennas with Reduced Cross-Polarization Radiation. 8. Broadband Dual-Frequency and Dual-Polarized Microstrip Antennas. 8.1 Introduction. 8.2 Broadband Dual-Frequency Microstrip Antennas. 8.3 Broadband Dual-Polarized Microstrip Antennas. 9. Broadband and Dual-Band Circularly Polarized Microstrip Antennas. 9.1 Introduction. 9.2 Broadband Single-Feed Circularly Polarized Microstrip Antennas. 9.3 Broadband Two-Feed Circularly Polarized Microstrip Antennas. 9.4 Broadband Four-Feed Circularly Polarized Microstrip Antennas. 9.5 Dual-Band Circularly Polarized Microstrip Antennas. Index.

Broadband Microstrip Antennas

Abstract: Look to this new, cutting-edge microstrip antenna book for the first exhaustive coverage of broadband techniques, including the most up-to-date information to help you choose and design the optimum broadband microstrip antenna configurations for your applications, without sacrificing other antenna parameters. The book shows you how to take advantage of the lightweight, low volume benefits of these antennas, by providing clear explanations of the various configurations and simple design equations that help you analyze and design microstrip antennas with speed and confidence. This practical resource offers you a comprehensive understanding of the radiation mechanism and characteristic of microstrip antennas, and provides guidance in designing new types of planar monopole antennas with multi-octave bandwidth. You learn how to select and design proper broadband microstrip antenna configurations for compact, tunable, dual-band and circular polarization applications. Moreover, the book compares all the broadband techniques and suggests the most attractive configuration. Extensively referenced with over 300 illustrations and 140 equations.

Fractal antennas: a novel antenna miniaturization technique, and applications

Abstract: Fractal geometry involves a recursive generating methodology that results in contours with infinitely intricate fine structures. This geometry, which has been used to model complex objects found in nature such as clouds and coastlines, has space-filling properties that can be utilized to miniaturize antennas. These contours are able to add more electrical length in less volume. In this article, we look at miniaturizing wire and patch antennas using fractals. Fractals are profoundly intricate shapes that are easy to define. It is seen that even though the mathematical foundations call for an infinitely complex structure, the complexity that is not discernible for the particular application can be truncated. For antennas, this means that we can reap the rewards of miniaturizing an antenna using fractals without paying the price of having to manufacture an infinitely complex radiator. In fact, it is shown that the required number of generating iterations, each of which adds a layer of intricacy, is only a few. A primer on the mathematical bases of fractal geometry is also given, focusing especially on the mathematical properties that apply to the analysis of antennas. Also presented is an application of these miniaturized antennas to phased arrays. It is shown how these fractal antennas can be used in tightly packed linear arrays, resulting in phased arrays that can scan to wider angles while avoiding grating lobes.

Resonator-based analysis of the combination of mobile handset antenna and chassis

Abstract: The performance of the mobile phone handset antenna-chassis combination is analyzed based on an approximate decomposition of the waves on the structure into two resonant wavemodes: the antenna-element wavemode and the chassis wavemode. A double resonator equivalent circuit model is presented and used to estimate the impedance bandwidth and the respective distributions of radiation losses with typical parameter values at 900 and 1800 MHz. It is noticed that at 900 MHz, the radiation losses of the antenna element wavemode represent typically less than 10% of the total power. Thus, the antenna element works mainly as a matching element, which couples to the low-Q resonant wavemode of the chassis. At 1800 MHz, the contribution of the antenna element wavemode is larger. By enhancing the coupling and by tuning the chassis resonance, it is possible to obtain an impedance bandwidth of over 50% (6 dB return loss) at both at 900 and 1800 MHz. The results given by the equivalent circuit study are fully supported by those of three-dimensional phone-model simulations, including calculation of the SAR and efficiency values. In prototyping, the 6 dB bandwidth of 5.5% was obtained at 980 MHz with a nonradiating coupling element with a volume of 1.6 cm/sup 3/ on a 120 mm long chassis.

A high-efficiency dual-frequency rectenna for 2.45- and 5.8-GHz wireless power transmission

Abstract: A dual-frequency printed dipole rectenna has been developed for the wireless power transmission at 2.45- and 5.8-GHz (industrial-scientific-medical bands). For operating at dual band, a new uniplanar printed dipole antenna is developed using a coupling method. A GaAs Schottky barrier diode analysis is performed, and a proper device requirement is discussed to have high RF-to-dc conversion efficiencies at both frequencies. A novel coplanar stripline (CPS) low-pass filter integrated with two additional open-ended T-strip CPS bandstop filters effectively block higher order harmonics generated from the diode. The measured conversion efficiencies achieved at free space are 84.4 and 82.7% at 2.45 and 5.8 GHz, respectively.

A broadband planar quasi-Yagi antenna

Abstract: A novel broadband planar antenna based on the classic Yagi-Uda dipole array is presented. This "quasi-Yagi" antenna achieves a measured 48% bandwidth for VSWR <2, better than 12 dB front-to-back ratio, smaller than -15 dB cross polarization, 3-5 dB absolute gain and a nominal efficiency of 93% across the operating bandwidth. Finite-difference time-domain simulation is used for optimization of the antenna and the results agree very well with measurements. Additionally, a gain-enhanced design is presented, where higher gain has been achieved at the cost of reduced bandwidth. These quasi-Yagi antennas are realized on a high dielectric constant substrate and are completely compatible with microstrip circuitry and solid-state devices. The excellent radiation properties of this antenna make it ideal as either a stand-alone antenna with a broad pattern or as an array element. The antenna should find wide applications in wireless communication systems, power combining, phased arrays and active arrays, as well as millimeter-wave imaging arrays.

A reconfigurable patch antenna using switchable slots for circular polarization diversity

Abstract: A novel design of a microstrip patch antenna with switchable slots (PASS) is proposed to achieve circular polarization diversity. Two orthogonal slots are incorporated into the patch and two pin diodes are utilized to switch the slots on and off. By turning the diodes on or off, this antenna can radiate with either right hand circular polarization (RHCP) or left hand circular polarization (LHCP) using the same feeding probe. Experimental results validate this concept. This design demonstrates useful features for wireless communication applications and future planetary missions.

An electromagnetic bandgap resonator antenna

Abstract: This paper introduces a new explanation of the electromagnetic bandgap (EBG) material properties using the study of the EBG structures in the frequency domain and reciprocal space. Once the behavior of such a material is understood, the properties of the EBG are used in order to make an EBG antenna. The antenna is realized with dielectric EBG rods. Its directivity is increased compared to a simple patch antenna. Such a device allows us to obtain a high gain with a very thin structure.

Printed ring slot antenna for circular polarization

Abstract: A new design of a microstrip-line-fed circularly polarized printed ring slot antenna is proposed. Circular polarization (CP) radiation of the proposed design is achieved by introducing proper asymmetry in the ring slot structure and feeding the ring slot using a microstrip line at 45/spl deg/ from the introduced asymmetry. The asymmetry introduced in the proposed design is a meandered-slot section and the proposed CP design can be applied to printed square and annular ring slot antennas. Prototypes of the proposed design have been implemented. Experimental results show that good CP radiation performances are obtained and the 3 dB axial-ratio CP bandwidths obtained for the square and annular ring slot antennas are about 4.3% and 3.5%, respectively.

Planar inverted-F antenna including a matching network having transmission line stubs and capacitor/inductor tank circuits

Abstract: A small multi-band planar inverted-F antenna (PIFA) includes a metal radiating element that is physically located above a metal ground plane element, and the space therebetween includes a frequency matching network having a microstrip transmission line that connects an antenna feed to a wireless communications device (WCD) feed. The impedance matching network may include a microstrip impedance transformer whose output provides a 50 ohm connection to the WCD. A number of microstrip stubs are connected to the microstrip transmission line. At least some of the microstrip stubs connect to the microstrip transmission line by way of a LC tank circuit. The LC tanks circuits are responsive to different ones of the multiple frequencies to which the PIFA is responsive, and in this manner the impedance matching network is dynamically reconfigured in accordance with the frequency band currently traversing the microstrip transmission line. The LC tanks circuits include discrete capacitors and inductors. A two-shot molding process is used to make a unitary plastic antenna assembly whose second-shot plastic surfaces are metallized in order to provide the antenna's metal elements, including the microstrip circuit pattern of the impedance matching network.

Broad-band dual-polarized single microstrip patch antenna with high isolation and low cross polarization

Abstract: This paper presents a new design of a broad-band dual-polarized single microstrip patch antenna with highly decoupled input ports and low cross-polarization (XP) radiation. A prototype of the proposed antenna with center frequency at 1800 MHz is presented. Both the dual linear polarizations have 10-dB return-loss impedance bandwidths greater than 14% and high decoupling between the two input ports (S/sub 21/ less than -40 dB across the entire bandwidths) is obtained. Moreover, the XP radiation in the principal planes of the dual linear polarizations is seen to be less than -20 dB.

Low-loss compact Butler matrix for a microstrip antenna

Abstract: This paper presents the design and realization of a double four-port Butler matrix to feed a four-column array antenna with two orthogonally polarized signals (to obtain polarization diversity). The main goals of this study are the reduction of the size and the losses of the network. In order to meet those requirements, a bi-layer structure, the suspended stripline, has been adopted to support the circuit. Moreover, the complete network has been integrated in a single unit. The double four-port Butler matrix has been etched on both sides of the suspended substrate to solve the problem of the cross between the lines. The broadside suspended 3-dB directional coupler has been chosen for the design of the 3-dB hybrid coupler. In order to change the side of the suspended substrate, contactless transitions have been used. The network is designed to work within the range of frequencies of the GSM-900-MHz standard: band 880 MHz-960 MHz, center frequency f/sub 0/=920 MHz. Measured losses for a 4/spl times/4 Butler matrix are 0.3 dB.

Analysis and design of an inverted-F antenna printed on a PCMCIA card for the 2.4 GHz ISM band

Abstract: The development of small integrated antennas plays a significant role in the progress of rapidly expanding commercial communication applications. This paper addresses the analysis and design of an inverted-F antenna (IFA) printed on a PCMCIA card. The antenna is compact, easy to manufacture, and efficient, with an omni-directional pattern and a bandwidth of 250 MHz. The performance of the integrated IFA/PCMCIA system was simulated using two commercial method of moments codes, and validated with measurements on a fabricated prototype.

Millimeter-wave folded reflector antennas with high gain, low loss, and low profile

Abstract: Periodic and quasi-periodic structures, printed on a dielectric substrate, can be employed to control the reflection and transmission properties of incident waves as a function of structure geometry. Local variations of the element geometry on a substrate with backside metallization - resulting in respective variations of the reflection phase angle - can be used to design printed reflectarray antennas. The dual-polarization properties of such antennas, together with polarizing grids or slot arrays, can be exploited for the realization of compact, low-profile folded reflector antennas. Examples of some antennas of this type are presented, covering the 60 GHz range for communication and ISM applications, and 76 to 77 GHz for automotive radars.

Comformal phased array antenna and method for repair

Abstract: A conformal phased array antenna and associated method of repairing the antenna are provided. The antenna has individual subassemblies or line replaceable units such that the antenna can be repaired without completely removing the entire antenna. The antenna generally includes a planar antenna subassembly including an array of RF modules disposed in a reference plane. The antenna also typically has a contoured waveguide subassembly including a contoured aperture honeycomb structure. The contoured aperture honeycomb structure defines a number of passages that are in communication with respective RF modules. The exterior surface of the contoured aperture honeycomb structure that faces away from the planar antenna subassembly is contoured such that at least portions of this surface are at an oblique angle with respect to the reference plane. This contoured surface may advantageously be shaped to match the contour of the surface of the structure to which the antenna is mounted.

Tunable horn antenna

Abstract: A family of FE dielectric-tuned antennas and a method for frequency tuning a wireless communications antenna are provided. The method comprises: forming a radiator; forming a dielectric with ferroelectric material proximate to the radiator; applying a voltage to the ferroelectric material; in response to applying the voltage, generating a dielectric constant; and, in response to the dielectric constant, communicating electromagnetic fields at a resonant frequency. Some aspects of the method further comprise: varying the applied voltage; and, modifying the resonant frequency in response to changes in the applied voltage. Modifying the resonant frequency includes forming an antenna with a variable operating frequency responsive to the applied voltage. Alternately stated, forming an antenna with a variable operating frequency includes forming an antenna with a predetermined fixed characteristic impedance, independent of the resonant frequency.

5.8-GHz circularly polarized rectifying antenna for wireless microwave power transmission

Abstract: This paper reports a new circularly polarized (CP) high-gain high-efficiency rectifying antenna (rectenna). The CP rectenna can be rotated and still maintain a constant dc output voltage. The high-gain antenna has an advantage of reducing the total number of rectenna elements to cover a fixed area. The rectenna is etched on Rogers Duroid 5870 substrate with /spl epsi//sub r/=2.33 and 10 mil thickness. A high-gain dual-rhombic-loop antenna and a reflecting plane are used to achieve a CP antenna gain of 10.7 dB and a 2:1 voltage standing-wave ratio bandwidth of 10%. The rectenna's pattern has an elliptical cross section with orthogonal beamwidths of 40/spl deg/ and 60/spl deg/. The rectenna circuit has a coplanar stripline band-reject filter that suppresses the re-radiated harmonics by 20 dB. A highly efficient Schottky diode is used for RF-to-dc conversion with an efficiency of approximately 80% for an input power level of 100 mW and a load resistance of 250 /spl Omega/.

Broadband dual-polarized aperture-coupled patch antennas with modified H-shaped coupling slots

Abstract: This paper presents a new design of aperture-coupled patch antennas with modified H-shaped coupling slots for achieving dual-polarization radiation with high isolation over a wide bandwidth. By using the proposed coupling slots, whose two upper side arms are bent inward with a proper angle, the isolation between the two feeding ports of the patch antenna can. greatly be improved, compared to the case with conventional H-shaped coupling slots. Also, when using a pair of modified H-shaped coupling slots for each feeding port, the isolation can further be improved; a high degree of isolation ( 20 dB) for the two polarizations can be achieved. Details of the proposed design and experimental results are presented and discussed.

Broadband dual-polarized patch antennas fed by capacitively coupled feed and slot-coupled feed

Abstract: Designs of broadband dual-polarized patch antennas fed by promising feed structures of a capacitively coupled feed and a slot-coupled feed (antenna A), two capacitively coupled feeds of a 180/spl deg/ phase shift and a slot-coupled feed (antenna B), and two capacitively coupled feeds of a 180/spl deg/ phase shift and two slot-coupled feeds (antenna C) are proposed and experimentally studied. The first two feed designs are for the excitation of a single-element broadband patch antenna, while the last design is for a two-element broadband patch antenna. These proposed patch antennas have a thick air substrate, and the 10 dB return-loss impedance bandwidths obtained for the two polarizations are all greater than 13%. High isolation ( 20 dB) in both E and H plane patterns for the two polarizations of antennas B and C are achieved.

A novel dual-mode bandpass filter with wide stopband using the properties of microstrip open-loop resonator

Abstract: A novel dual-mode microstrip square loop resonator is proposed using the slow-wave and dispersion features of the microstrip slow-wave open-loop resonator. It is shown that the designed and fabricated dual-mode microstrip filter has a wide stopband including the first spurious resonance frequency. Also, it has a size reduction of about 50% at the same center frequency, as compared with the dual-mode bandpass filters such as microstrip patch, cross-slotted patch, square loop, and ring resonator filter.

Investigations into a cavity-backed circular-patch antenna

Abstract: An empirical formula for resonant frequency of a circular cavity-enclosed circular-patch antenna is tested with measured results. The patch miniaturization in the presence of the cavity is proved. Different design curves in terms of resonant frequencies and bandwidth are derived to facilitate antenna design without a priori knowledge of complex numerical techniques. A simple gain formula for a circular-patch antenna is derived and tested against the measured gain data. The results agree very well. The beamwidth, axial ratio, and mutual coupling in the presence of the cavity are investigated.

Fractal antenna ground counterpoise, ground planes, and loading elements and microstrip patch antennas with fractal structure

Abstract: An antenna system includes a fractalized element that may be a ground counterpoise, a top-hat located load assembly, or a microstrip patch antenna having at least one element whose physical shape is at least partially defined as a first or higher iteration deterministic fractal. The resultant fractal element may rely upon an opening angle for performance, and is more compact than non-Euclidean ground counterpoise elements or the like. A vertical antenna system includes a vertical element that may also be a fractal, and a vertical antenna can include vertically spaced-apart fractal conductive and passive elements, and at least one fractal ground element. Various antenna configurations may be fabricated on opposite surfaces of a substrate, including a flexible substrate, and may be tuned by rotating elements relative to each other, and/or by varying the spaced-apart distance therebetween. Fractalized ground counterpoise elements and/or microstrip patch antenna systems may be fabricated on a flexible printed circuit substrate, and/or placed within the support mount of a cellular telephone car antenna.

Wideband smart antenna theory using rectangular array structures

Abstract: Smart antenna techniques at the base station can dramatically improve the performance of the mobile radio system by employing spatial filtering. The design of a fully spatial signal processor using rectangular array configuration is proposed. Two-dimensional (2-D) spatial filters that can be implemented by microstrip technology are capable of filtering the received signal in the angular domain as well as the frequency domain. Furthermore, it has wideband properties and, hence, eliminates the requirement of different antenna spacing for applications including various carrier frequencies. The desired frequency selectivity of the smart antenna can be combined with compensation of the undesired frequency performance of a single antenna element, and the result is quite satisfactory for practical implementation. In addition, if the elements of the array are not perfectly omnidirectional or frequency independent, we can compensate for these deficiencies in the design algorithm. Two different algorithms for calculating the real-valued weights of the antenna elements are proposed. The first algorithm is more complex but leads to sharper beams and controlled performance. The second method is simpler but has wider beam and lower fractional bandwidth. Some computer simulation results demonstrating the directional beam patterns of the designed beamformers are also presented.

Broadband dual polarization patch element for cellular-phone base stations

Abstract: A broadband dual polarization patch antenna double fed by an L-shaped probe and a near-resonant aperture is presented. The proposed antenna achieves a 1.5:1 standing wave ratio bandwidth of >20% at the two ports. Input isolation exceeding 25 dB has been obtained in the wide bandwidth. Thus, it can potentially be used as a base station antenna for cellular-phone networks.

Novel design of broad-band stacked patch antenna

Abstract: A novel broadband stacked E-shaped patch antenna is proposed in this paper. The proposed antenna has an input impedance bandwidth of about 38.41%, better than the conventional E-shaped microstrip patch antenna, which has an input impedance bandwidth of 33.8%. Through the use of the washer on the probe of the stacked patch antenna, the input impedance bandwidth is improved further to 44.9%. The radiation patterns are found to be relatively constant throughout the whole band. Comparisons of these antennas are presented in this paper.

Miniature microstrip antenna with a partially filled high-permittivity substrate

Abstract: A new technique to reduce the overall dimension of a microstrip antenna using a partially filled high-permittivity substrate is proposed The miniaturized microstrip antenna for a repeater system in a mobile communication cellular band (824-894 MHz) is designed with the proposed technique and manufactured with light weight and small size Comparison between simulations, based on HP HFSS software, and measurements are provided

A quarter-wave U-shaped patch antenna with two unequal arms for wideband and dual-frequency operation

Abstract: A wideband and dual-frequency quarter-wave U-shaped patch antenna with two unequal arms on FR4 substrate is presented. The U-shaped patch antenna is fed electromagnetically by another coaxially-fed patch on the same layer, which operates at a higher frequency band. In this paper, we first proposed a new technique to obtain two closely staggered resonant modes to achieve a wide impedance bandwidth using two unequal arms of the U-shaped patch for the lower band. For the substrate thickness = 5, 7.5 and 11 mm, the measured bandwidths of the antennas operating around at 900 MHz are 7%, 10%, and 18%, respectively. Then, we modify the coaxially-fed patch so that both bands are wide in bandwidth. The resulting antenna operating at 900 and 1800-MHz bands with the substrate thickness 11 mm has a measured impedance bandwidth of 13.3% and 20 respectively. This thickness corresponds to 0.033 free-space wavelength at 900 MHz. The far-field radiation patterns are stable in the two operating bands. The proposed antenna is simple in structure compared with the regular stacked or coplanar parasitic patch antennas. It is highly suitable for indoor mobile communications.

Design of defected ground structures for harmonic control of active microstrip antenna

Abstract: Photonic bandgap (PBG) structures are usually periodic structures in which propagation of a certain band of frequencies is prohibited. PBG structures for microwave frequencies are applied in planar circuits such as microstrip line and CPW (coplanar waveguide). In this case, they are more frequently termed defected ground structures (DGS). Most of the research performed on DGS has been based on the equivalent circuit consisting of lumped elements, L and C, extracted from EM simulations (see D. Ahn et al., IEEE MTT, vol.49, 2001). In addition, we also consider radiation effects by including resistance, R, in the equivalent circuit. The general 1D periodic structures with N unit cells are analyzed using an ABCD matrix formulation. The effects of the RLC elements of the unit cell, the spacing between the unit cells, and the cell number, N, are investigated in detail. For a design example, a simple 1D DGS with N=2 is designed for harmonic control through a modeling using transmission line theory. This 1D DGS with N=2 is much simpler than the one proposed by Y. Horii and M. Tsutsmi (see IEEE MGWL, vol.9, no.1. p.1895-8, 1999). The proposed approach enables us to design the required DGS quite easily and quickly.

Printed diversity monopole antenna for WLAN operation

Abstract: A printed diversity monopole antenna for WLAN operation in the 2.4 GHz band is presented. The antenna comprises two orthogonal linear monopoles placed symmetrically with respect to a T-shaped ground plane between them. The antenna has two highly decoupled ports and can provide spatial diversity to combat the multipath interference problem.