Showing papers on "Patch 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.

Dominant mode leaky-wave antenna with backfire-to-endfire scanning capability

Abstract: A novel dominant mode leaky-wave antenna is proposed. This antenna is a transmission line structure with radiating wavenumber increasing from negative to positive values, providing backward to forward scanning capability as the frequency is increased. The characteristics and performances of the antenna are demonstrated by full-wave simulation and measurement results.

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.

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.

A built-in, multi band, multi antenna system

Abstract: A build-in, multi band, multi antenna system (1) for a protable communicaiton device (10) has a first antenna (2, 4, 5), which is resonant in first an second frequency band. A secon antenna (3) is resonant in a fourth frequency bank. The first antenna, the papasitic element and the second antenna are provided on a common flexible substrate.

High-strength microwave antenna assemblies

Abstract: Various high-strength microwave antenna assemblies are described herein. The microwave antenna has a radiating portion connected by a feedline to a power generating source, e.g., a generator. The antenna is a dipole antenna with the distal end of the radiating portion being tapered and terminating at a tip to allow for direct insertion into tissue. Antenna rigidity comes from placing distal and proximal radiating portions in a pre-stressed state, assembling them via threaded or overlapping joints, or fixedly attaching an inner conductor to the distal portion. The inner conductor is affixed to the distal portion by, e.g., welding, brazing, soldering, or by adhesives. A junction member made from a hard dielectric material, e.g., ceramic, can be placed between the two portions and can have uniform or non-uniform shapes to accommodate varying antenna designs. Electrical chokes may also be used to contain returning currents to the distal end of the antenna.

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.

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.

Leaky CPW-based slot antenna arrays for millimeter-wave applications

Abstract: A uniplanar leaky-wave antenna (LWA) suitable for operation at millimeter-wave frequencies is introduced. Both unidirectional and bidirectional versions of the antenna are presented. The proposed structure consists of a coplanar waveguide fed linear array of closely spaced capacitive transverse slots. This configuration results in a fast-wave structure in which the n=0 spatial harmonic radiates in the forward direction. Since the distance, d, between adjacent elements of the array is small d/spl Lt//spl lambda//sub o/, the slot array essentially becomes a uniform LWA. A comprehensive transmission line model is developed based upon the theory of truncated periodic transmission lines to explain the operation of the antenna and provide a tool for its design. Measured and simulated radiation patterns, directivity, gain, and an associated loss budget are presented for a 32-element antenna operating at 30 GHz. The uniplanar nature of the structure makes the antenna appropriate for integration of shunt variable capacitors such as diode or micro-electromechanical system varactors for fixed frequency beam steering at low-bias voltages.

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.

Method and system for improving isolation in radio-frequency antennas

Abstract: In an antenna structure having a transmit antenna disposed over a first section of a ground plane and a receive antenna disposed over a second section of the ground plane, a cut is provided between the first and second sections of the ground plane. The length of the cut is substantially equal to one quarter-wavelength of the operating frequency band of transmit/receive antenna pair so as to provide isolation between the transmit antenna and the receive antenna. If the antenna structure also has a transceiver antenna operated in a further frequency band disposed over the same ground plane and straddling over the first section and the second section, a switch is provided over the cut. The switch is operating in a closed position when the transceiver antenna in the further frequency band is used, and in an open position when the transmit/receiver antenna pair is used.

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.

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.

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.

A steerable leaky-wave antenna using a tunable impedance ground plane

Abstract: A steerable leaky-wave antenna is built using a mechanically tunable impedance surface. A horizontally polarized antenna couples energy into leaky transverse electric waves on a tunable textured ground plane. By tuning the resonance frequency of the surface, the band structure is shifted in frequency, which changes the tangential wave vector of the leaky waves for a fixed frequency. This steers the elevation angle of the resulting radiated beam. This steerable leaky-wave antenna can scan over a range of 45/spl deg/ using a mechanical movement of about 1/500 wavelength.

A dual-band planar inverted-F patch antenna with a branch-line slit

Abstract: By embedding a branch-line slit in the radiating patch of a planar inverted-F patch antenna, novel 900 and 1800 MHz dual-band operation is obtained. The embedded branch-line slit has two branch slits (one long folded slit and one short bent slit) protruding from the main slit which has an open end at the patch boundary. The main slit and the long folded branch slit together strongly meander the excited patch surface currents starting from the feed to the portion of the patch encircled by the folded branch slit, which leads to a significant reduction in the required dimensions for the proposed antenna. In addition, the two operating frequencies have wavelengths corresponding to about 4.0 and 2.0 times the length of the above-mentioned meandered patch surface current path. The short bent branch slit, on the other hand, mainly serves as a tuning slit for achieving good impedance matching of the two operating frequencies. The proposed antenna and experimental results are described in detail in this paper. © 2002 John Wiley & Sons, Inc. Microwave Opt Technol Lett 32: 310–312, 2002.

A dual-band GPS microstrip antenna

Abstract: Design considerations and experimental results of a dual-band circularly polarized stacked microstrip antenna for GPS operations at 1227 and 1575 MHz are presented. The antenna is achieved by stacking two corner-truncated square microstrip patches. The obtained circular polarization (CP) bandwidths, determined from 3-dB axial ratio, are about 15 MHz (about 1.2%) and 17 MHz (about 1.1%) at 1227 and 1575 MHz, respectively. Good CP radiation patterns and antenna gain have also been observed. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 33: 238–240, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10285

Integration of filters and microstrip antennas

Abstract: A new implementation of the integrated antenna-filter module has been proposed that is based on the single material technology and uses the same substrate for both the antenna and filter layers. An X band device has been designed on the low permittivity substrate and examined for X band operation. This example proves the feasibility of achieving a well-defined filtering response and proper radiation performance through simple and compact integrated modules.

Broadband probe-fed patch antenna with a W-shaped ground plane

Abstract: A new design of a broadband probe-fed patch antenna with a W-shaped ground plane is presented. The W-shaped ground plane is obtained by bending the conventional planar ground plane into an inverted V-shape, seen in the resonant direction of the patch antenna and then adding proper flanges at the two straight edges of the bent ground plane. The proposed design is applicable to the patch antenna with a planar radiating patch with a thin air substrate. With the use of the proposed W-shaped ground plane, the required probe-pin length in the substrate remains small, although the effective substrate thickness is significantly increased, resulting in a much wider operating bandwidth. Also, by choosing proper dimensions of the W-shaped ground plane, the antenna gain for frequencies over the obtained wide bandwidth is enhanced, compared to the conventional patch antenna with a planar ground plane. In addition, the cross polarization is also reduced for the proposed design and the cross-polarization level (XPL) in the H-plane pattern can even be better than that of a conventional probe-fed patch antenna with a thin air substrate.

Multi frequency stacked patch antenna with improved frequency band isolation

Abstract: The invention is a stacked patch antenna having a plurality of patch antennas having respective operating frequency bands arranged in a stack, each antenna comprising a radiating conductive patch and a first cable comprising a plurality of coaxial conductors separated from each other by dielectric A first conductor of the first cable carries the feed signal for the uppermost antenna and is conductively coupled to a null point of the radiating conductive patch of the uppermost antenna and passes through apertures at the null points of the other ones of the antennas in the stack Each of the successively lower antennas in the stack is coupled to another one of the plurality of conductors of the cable, which conductors reference the other patches to ground With this arrangement, high isolation is maintained between the frequency operating bands Another antenna can be added between each consecutive pair of antennas discussed above, these antennas being fed by the same feed conductor as the antenna above it by parasitic coupling with the antenna above it

Multiple frequency bands switchable antenna for portable terminals

Abstract: A tuneable quad-band radio antenna device (1) for a radio communication terminal, said antenna device comprising a ground substrate (2), a dual-band antenna element comprising a first elongated antenna member (3), a second (4) elongated antenna member, which is shorter than said first member, and a ground connection (11,12) connecting said members to ground. An impedance switch device (20) is operable to change the impedance of said connection (11,12) for tuning the antenna element, such that in a first impedance setting (Z1,Z3) the antenna element is resonant to a first and a second radio frequency, and in a second impedance setting (Z2,Z4) the antenna element is resonant to a third and a fourth radio frequency which are frequency shifted from said first and second radio frequencies.