Showing papers on "Microstrip published in 2006"

Conformal array antenna theory and design

Abstract: Preface. Abbreviations and Acronyms. 1 INTRODUCTION. 1.1 The Definition of a Conformal Antenna. 1.2 Why Conformal Antennas? 1.3 History. 1.4 Metal Radomes. 1.5 Sonar Arrays. References. 2 CIRCULAR ARRAY THEORY. 2.1 Introduction. 2.2 Fundamentals. 2.2.1 Linear Arrays. 2.2.2 Circular Arrays. 2.3 Phase Mode Theory. 2.3.1 Introduction. 2.3.2 Discrete Elements. 2.3.3 Directional Elements. 2.4 The Ripple Problem in Omnidirectional Patterns. 2.4.1 Isotropic Radiators. 2.4.2 Higher-Order Phase Modes. 2.4.3 Directional Radiators. 2.5 Elevation Pattern. 2.6 Focused Beam Pattern. References. 3 THE SHAPES OF CONFORMAL ANTENNAS. 3.1 Introduction. 3.2 360- Coverage. 3.2.1 360- Coverage Using Planar Surfaces. 3.2.2 360- Coverage Using a Curved Surface. 3.3 Hemispherical Coverage. 3.3.1 Introduction. 3.3.2 Hemispherical Coverage Using Planar Surfaces. 3.3.3 Half Sphere. 3.3.4 Cone. 3.3.5 Ellipsoid. 3.3.6 Paraboloid. 3.3.7 Comparing Shapes. 3.4 Multifaceted Surfaces. 3.5 References. 4 METHODS OF ANALYSIS. 4.1 Introduction. 4.2 The Problem. 4.3 Electrically Small Surfaces. 4.3.1 Introduction. 4.3.2 Modal Solutions. 4.3.2.1 Introduction. 4.3.2.2 The Circular Cylinder. 4.3.2.3 A Unit Cell Approach. 4.3.3 Integral Equations and the Method of Moments. 4.3.4 Finite Difference Time Domain Methods (FDTD). 4.3.4.1 Introduction. 4.3.4.2 Conformal or Contour-Patch (CP) FDTD. 4.3.4.3 FDTD in Global Curvilinear Coordinates. 4.3.4.4 FDTD in Cylindrical Coordinates. 4.3.5 Finite Element Method (FEM). 4.3.5.1 Introduction. 4.3.5.2 Hybrid FE-BI Method. 4.4 Electrically Large Surfaces. 4.4.1 Introduction. 4.4.2 High-Frequency Methods for PEC Surfaces. 4.4.3 High-Frequency Methods for Dielectric Coated Surfaces. 4.5 Two Examples. 4.5.1 Introduction. 4.5.2 The Aperture Antenna. 4.5.3 The Microstrip-Patch Antenna. 4.6 A Comparison of Analysis Methods. Appendix 4A-Interpretation of the ray theory. 4A.1 Watson Transformation. 4A.2 Fock Substitution. 4A.3 SDP Integration. 4A.4 Surface Waves. 4A.5 Generalization. References. 5 GEODESICS ON CURVED SURFACES. 5.1 Introduction. 5.1.1 Definition of a Surface and Related Parameters. 5.1.2 The Geodesic Equation. 5.1.3 Solving the Geodesic Equation and the Existence of Geodesics. 5.2 Singly Curved Surfaces. 5.3 Doubly Curved Surfaces. 5.3.1 Introduction. 5.3.2 The Cone. 5.3.3 Rotationally Symmetric Doubly Curved Surfaces. 5.3.4 Properties of Geodesics on Doubly Curved Surfaces. 5.3.5 Geodesic Splitting. 5.4 Arbitrarily Shaped Surfaces. 5.4.1 Hybrid surfaces. 5.4.2 Analytically Described Surfaces. References. 6 ANTENNAS ON SINGLY CURVED SURFACES. 6.1 Introduction. 6.2 Aperture Antennas on Circular Cylinders. 6.2.1 Introduction. 6.2.2 Theory. 6.2.3 Mutual Coupling. 6.2.3.1 Isolated Mutual Coupling. 6.2.3.2 Cross Polarization Coupling. 6.2.3.3 Array mutual coupling. 6.2.4 Radiation Characteristics. 6.2.4.1 Isolated-Element Patterns. 6.2.4.2 Embedded-Element Patterns. 6.3 Aperture Antennas on General Convex Cylinders. 6.3.1 Introduction. 6.3.2 Mutual Coupling. 6.3.2.1 The Elliptic Cylinder. 6.3.2.2 The Parabolic Cylinder. 6.3.2.3 The Hyperbolic Cylinder. 6.3.3 Radiation Characteristics. 6.3.3.1 The Elliptic Cylinder. 6.3.3.2 End Effects. 6.4 Aperture Antennas on Faceted Cylinders. 6.4.1 Introduction. 6.4.2 Mutual Coupling. 6.4.3 Radiation Characteristics. 6.5 Aperture Antennas on Dielectric Coated Circular Cylinders. 6.5.1 Introduction. 6.5.2 Mutual Coupling. 6.5.2.1 Isolated Mutual Coupling. 6.5.2.2 Array Mutual Coupling. 6.5.3 Radiation Characteristics. 6.5.3.1 Isolated-Element Patterns. 6.5.3.2 Embedded-Element Patterns. 6.6 Microstrip-Patch Antennas on Coated Circular Cylinders. 6.6.1 Introduction. 6.6.2 Theory. 6.6.3 Mutual Coupling. 6.6.3.1 Single-Element Characteristics. 6.6.3.2 Isolated and Array Mutual Coupling. 6.6.4 Radiation Characteristics. 6.6.4.1 Isolated-Element Patterns. 6.6.4.2 Embedded-Element Patterns. 6.7 The Cone. 6.7.1 Introduction. 6.7.2 Mutual Coupling. 6.7.2.1 Aperture Antennas. 6.7.2.2 Microstrip-Patch Antennas. 6.7.3 Radiation Characteristics. 6.7.3.1 Aperture Antennas 248 6.7.3.2 Microstrip-Patch Antennas. References. 7 ANTENNAS ON DOUBLY CURVED SURFACES. 7.1 Introduction. 7.2 Aperture Antennas. 7.2.1 Introduction. 7.2.2 Mutual Coupling. 7.2.2.1 Isolated Mutual Coupling. 7.2.2.2 Array Mutual Coupling. 7.2.3 Radiation Characteristics. 7.3 Microstrip-Patch Antennas. 7.3.1 Introduction. 7.3.2 Mutual Coupling. 7.3.2.1 Single-Element Characteristics. 7.3.2.2 Isolated Mutual Coupling. 7.3.3 Radiation Characteristics. References. 8 CONFORMAL ARRAY CHARACTERISTICS. 8.1 Introduction. 8.2 Mechanical Considerations. 8.2.1 Array Shapes. 8.2.2 Element Distribution on a Curved Surface. 8.2.3 Multifacet Solutions. 8.2.4 Tile Architecture. 8.2.5 Static and Dynamic Stress. 8.2.6 Other Electromagnetic Considerations. 8.3 Radiation Patterns. 8.3.1 Introduction. 8.3.2 Grating Lobes. 8.3.3 Scan-Invariant Pattern. 8.3.4 Phase-Scanned Pattern. 8.3.5 A Simple Aperture Model for Microstrip Arrays. 8.4 Array Impedance. 8.4.1 Introduction. 8.4.2 Phase-Mode Impedance. 8.5 Polarization. 8.5.1 Polarization Definitions. 8.5.2 Cylindrical Arrays. 8.5.2.1 Dipole Elements. 8.5.2.2 Aperture elements. 8.5.3 Polarization in Doubly Curved Arrays. 8.5.3.1 A Paraboloidal Array. 8.5.4 Polarization Control. 8.6 Characteristics of Selected Conformal Arrays. 8.6.1 Nearly Planar Arrays. 8.6.2 Circular Arrays. 8.6.3 Cylindrical Arrays. 8.6.4 Conical Arrays. 8.6.5 Spherical Arrays. 8.6.6 Paraboloidal Arrays. 8.6.7 Ellipsoidal Arrays. 8.6.8 Other Shapes. References. 9 BEAM FORMING. 9.1 Introduction. 9.2 A Note on Orthogonal Beams. 9.3 Analog Feed Systems. 9.3.1 Vector Transfer Matrix Systems. 9.3.2 Switch Matrix Systems. 9.3.3 Butler Matrix Feed Systems. 9.3.4 RF Lens Feed Systems. 9.3.4.1 The R-2R Lens Feed. 9.3.4.2 The R-kR Lens Feed. 9.3.4.3 Mode-Controlled Lenses. 9.3.4.4 The Luneburg Lens. 9.3.4.5 The Geodesic Lens. 9.3.4.6 The Dome Antenna. 9.4 Digital Beam Forming. 9.5 Adaptive Beam Forming. 9.5.1 Introduction. 9.5.2 The Sample Matrix Inversion Method. 9.5.3 An Adaptive Beam Forming Simulation Using a Circular Array. 9.6 Remarks on Feed Systems. References. 10 CONFORMAL ARRAY PATTERN SYNTHESIS. 10.1 Introduction. 10.2 Shape Optimization. 10.3 Fourier Methods for Circular Ring Arrays. 10.4 Dolph-Chebysjev Pattern Synthesis. 10.4.1 Isotropic Elements. 10.4.2 Directive Elements. 10.5 An Aperture Projection Method. 10.6 The Method of Alternating Projections. 10.7 Adaptive Array Methods. 10.8 Least-Mean-Squares Methods (LMS). 10.9 Polarimetric Pattern Synthesis. 10.10 Other Optimization Methods. 10.11 A Synthesis Example Including Mutual Coupling. 10.12 A Comparison of Synthesis Methods. References. 11 SCATTERING FROM CONFORMAL ARRAYS. 11.1 Introduction. 11.2 Definitions. 11.3 Radar Cross Section Analysis. 11.3.1 General. 11.3.2 Analysis Method for an Array on a Conducting Cylinder. 11.3.3 Analysis Method for an Array on a Conducting Cylinder with a Dielectric Coating. 11.4 Cylindrical Array. 11.4.1 Analysis and Experiment-Rectangular Grid. 11.4.2 Higher-Order Waveguide Modes. 11.4.3 Triangular Grid. 11.4.4 Conclusions from the PEC Conformal Array Analysis. 11.5 Cylindrical Array with Dielectric Coating. 11.5.1 Single Element with Dielectric Coating. 11.5.2 Array with Dielectric Coating. 11.6 Radiation and Scattering Trade-off. 11.6.1 Introduction. 11.6.2 Single-Element Results. 11.6.3 Array Results. 11.7 Discussion. References. Subject Index. About the Authors.

Design and Characterization of Purely Textile Patch Antennas

Abstract: In this paper, we present four purely textile patch antennas for Bluetooth applications in wearable computing using the frequency range around 2.4 GHz. The textile materials and the planar antenna shape provide a smooth integration into clothing while preserving the typical properties of textiles. The four antennas differ in the deployed materials and in the antenna polarization, but all of them feature a microstrip line as antenna feed. We have developed a manufacturing process that guarantees unaffected electrical behavior of the individual materials when composed to an antenna. Thus, the conductive textiles possess a sheet resistance of less than 1Omega/squarein order to keep losses at a minimum. The process also satisfies our requirements in terms of accuracy meeting the Bluetooth specifications. Our investigations not only characterize the performance of the antennas in planar shape, but also under defined bending conditions that resemble those of a worn garment. We show that the antennas can withstand clothing bends down to a radius of 37.5 mm without violating specifications

Half Mode Substrate Integrated Waveguide: A New Guided Wave Structure for Microwave and Millimeter Wave Application

Abstract: In this paper, a new guided wave structure of half mode substrate integrated waveguide (HMSIW) for microwave and millimeter wave application is proposed for the first time. The principle of the HMSIW is described, and its propagation characteristics are simulated and measured. The measured results at microwave and millimeter wave bands show that the attenuation of it is less than that of conventional microstrip and even SIW, but its size is nearly half of a SIW. Thus, we can further compress the size of a microwave or millimeter wave integrated circuit based on this new guided wave structure.

Shielded passive devices for silicon-based monolithic microwave and millimeter-wave integrated circuits

Abstract: This paper introduces floating shields for on-chip transmission lines, inductors, and transformers implemented in production silicon CMOS or BiCMOS technologies. The shield minimizes losses without requiring an explicit on-chip ground connection. Experimental measurements demonstrate Q-factor ranging from 25 to 35 between 15 and 40 GHz for shielded coplanar waveguide fabricated on 10 /spl Omega//spl middot/cm silicon. This is more than a factor of 2 improvement over conventional on-chip transmission lines (e.g., microstrip, CPW). A floating-shielded, differentially driven 7.4-nH inductor demonstrates a peak Q of 32, which is 35% higher than an unshielded example. Similar results are realizable for on-chip transformers. Floating-shielded bond-pads with 15% less parasitic capacitance and over 60% higher shunt equivalent resistance compared to conventional shielded bondpads are also described. Implementation of floating shields is compatible with current and projected design constraints for production deep-submicron silicon technologies without process modifications. Application examples of floating-shielded passives implemented in a 0.18-/spl mu/m SiGe-BiCMOS are presented, including a 21-26-GHz power amplifier with 23-dBm output at 20% PAE (at 22 GHz), and a 17-GHz WLAN image-reject receiver MMIC which dissipates less than 65 mW from a 2-V supply.

De-embedding transmission line measurements for accurate modeling of IC designs

Abstract: A new technique to de-embed the contributions of parasitic structures from transmission line measurements is presented and applied to microstrip lines fabricated in 90- and 130-nm RF-CMOS technologies. De-embedded measurements are used to extract characteristic impedance, attenuation constant, group delay, and effective permittivity. The effective thickness of the ground plane is demonstrated to be as important as the thickness of the top metal layer in minimizing interconnect loss. Furthermore, it is confirmed that metal area densities as low as 65% are adequate for the ground plane of microstrip lines.

Study of printed elliptical/circular slot antennas for ultrawideband applications

Abstract: Two novel designs of planar elliptical slot antennas are presented. Printed on a dielectric substrate and fed by either microstrip line or coplanar waveguide with U-shaped tuning stub, the elliptical/circular slots have been demonstrated to exhibit an ultrawideband characteristic. The performances and characteristics of the proposed antennas are investigated both numerically and experimentally. Based on these analyses, an empirical formula is introduced to approximately determine the lower edge of the -10 dB operating bandwidth. It is also shown that these antennas are nearly omnidirectional over a majority fraction of the bandwidth.

Novel microstrip bandpass filters based on complementary split-ring resonators

Abstract: In this paper, a new methodology for the design of compact planar filters in microstrip technology is proposed. This is based on cascading filter stages consisting of the combination of complementary split-ring resonators (CSRRs), recently proposed by the authors, series capacitive gaps, and grounded stubs. By this means, we achieve the necessary flexibility to simultaneously obtain quite symmetric frequency responses, controllable bandwidths, and compact dimensions. Two prototype device bandpass filters are provided to illustrate the potentiality of the proposed approach. In the first prototype, the structure is periodic (i.e., composed of identical cells) and behaves as a left-handed transmission line with controllable bandwidth. In the second prototype device, periodicity is sacrificed with an eye toward the synthesis of a standard (Chebyshev) approximation. The measured frequency responses point out low insertion losses in the passband, as well as high-frequency selectivity with small dimensions. As compared to conventional parallel coupled line filters, reduction of device length by a factor of 2.4 is demonstrated. This is the first time that planar filters with controllable bandwidth based on CSRRs are achieved. These structures can be of interest in those applications where miniaturization and compatibility with planar circuit technology are key issues

Design of Dual- and Triple-Passband Filters Using Alternately Cascaded Multiband Resonators

Abstract: A novel method for designing multiband bandpass filters has been proposed in this paper. Coupling structures with both Chebyshev and quasi-elliptic frequency responses are presented to achieve dual- and triple-band characteristics without a significant increase in circuit size. The design concept is to add some extra coupled resonator sections in a single-circuit filter to increase the degrees of freedom in extracting coupling coefficients of a multiband filter and, therefore, the filter is capable of realizing the specifications of coupling coefficients at all passbands. To verify the presented concept, four experimental examples of filters with a dual-band Chebyshev, triple-band Chebyshev, dual-band quasi-elliptic, and triple-band quasi-elliptic response have been designed and fabricated with microstrip technology. The measured results are in good agreement with the full-wave simulation results

Microstrip diplexers design with common resonator sections for compact size, but high isolation

Abstract: High isolation and compact size microstrip diplexers designed with common resonator sections have been proposed. By exploiting the variable frequency response of the stepped-impedance resonator, resonators can be shared by the two filter channels of the desired diplexer if their fundamental and the first spurious resonant frequency are properly assigned. Size reduction are, therefore, achieved by introducing a few common resonator sections in the circuit. This concept has been verified by the experimental results of two diplexer circuits. One of the diplexers is composed of two three-pole parallel-coupled bandpass filters and the other is composed of two four-pole cross-coupled bandpass filters, which are formed by only five and six resonators, respectively. Both of them occupy extremely small areas while still keeping good isolations. Good agreements are also achieved between measurement and simulation.

A simple and effective method for microstrip dual-band filters design

Abstract: A new type of novel low loss dual-band microstrip filters using folded open-loop ring resonators (OLRRs) is presented in this letter. Both magnetic and electric coupling structures are implemented to provide high performance passband response. The first passband and second passband of the designed dual-band filter can be easily and accurately shifted to a desired frequency band by adjusting the physical dimensions of OLRRs. Finally, the 2.4-GHz/5.7-GHz and 2.4-GHz/5.2-GHz dual-band filters are illustrated and measured in this letter.

Circular and Elliptical CPW-Fed Slot and Microstrip-Fed Antennas for Ultrawideband Applications

Abstract: This letter presents novel circular and elliptical coplanar waveguide (CPW)-fed slot and mictrostip-fed antenna designs targeting the 3.1?10.6 GHz band. The antennas are comprised of elliptical or circular stubs that excite similar-shaped slot apertures. Four prototypes have been examined, fabricated and experimentally tested, the three being fed by a CPW and the fourth by a microstrip line, exhibiting a very satisfactory behavior throughout the 7.5 GHz of the allocated bandwidth in terms of impedance matching $(hbox VSWR?2)$, radiation efficiency and radiation pattern characteristics. Measured impedance bandwidths of beyond 175% will be presented.

Capacitive-Ended Interdigital Coupled Lines for UWB Bandpass Filters With Improved Out-of-Band Performances

Abstract: This letter presents a novel ultra-wideband (UWB) microstrip bandpass filter on a microstrip line with improved out-of-band performances. A multiple-mode resonator (MMR) is first constituted to equally allocate its first three resonant frequencies in the 3.1-10.6-GHz UWB band. Two capacitive-ended interdigital coupled lines are then formed to assign their transmission zero towards the fourth-order resonant frequency of this MMR, thereby suppressing the first spurious passband. Moreover, two outer arms in the interdigital lines are properly tapered to compensate the phase imbalance or group delay near the UWB upper-end relying on extra capacitive-ended stubs. And finally, two UWB filters with one- and two-MMRs are designed and implemented to experimentally demonstrate the improved out-of-band performances, i.e., widened/deepened upper-stopband and sharpened rejection skirts outside the UWB passband

Theory and analysis of differentially-driven microstrip antennas

Abstract: This paper studies differentially-driven microstrip antennas. The theory of microstrip antennas based on the improved cavity model is expanded to analyze the input impedance and radiation characteristics of the differentially-driven microstrip antennas. The differentially-driven microstrip antennas were fabricated. Their performances were experimentally verified. Results show that the occurrence of resonance for the differentially-driven microstrip antennas also depends on the ratio of the separation /spl xi/ of the dual feeds to the free-space wavelength /spl lambda//sub o/. When the dual feeds are located far from each other /spl xi///spl lambda//sub o/>0.1, the resonance occurs, and the input resistance at resonance is rather large. However, when the dual feeds are located near to each other /spl xi///spl lambda//sub o/<0.1, the resonance does not occur, the input resistance is quite small, and the input impedance is inductive. Compared with single-ended microstrip antennas, the differentially-driven microstrip antennas have larger resonant resistance, similar co-polar radiation patterns, and lower cross-polar radiation component.

A Compact Microstrip Square-Ring Slot Antenna for UWB Applications

Abstract: A microstrip square-ring slot antenna (MSRSA) for UWB (Ultra Wideband) antenna applications is proposed and improved by compaction. This structure is fed by a single microstrip line with a fork like-tuning stub. By splitting the square-ring slot antenna (SRSA) and optimization of the feeding network, the required impedance bandwidth is achieved over the UWB frequency range (3.1 to 10.6 GHz). The experimental and simulation results exhibit good agreement together. Parametric study is applied to compaction of structure. This compaction provides a good radiation pattern and a relatively constant gain over the entire band of frequency.

A novel defected ground structure for planar circuits

Abstract: A new compact defected ground structure (DGS) is proposed for the microstrip line. The structure is compact in microstrip line direction. Here, this DGS is used to design a compact low pass filter (LPF) that is at least 26.3% more compact lengthwise than other reported compact structures and has sharper transition knee.

Miniaturized microstrip lowpass filter with wide stopband using double equilateral U-shaped defected ground structure

Abstract: A compact double equilateral U-shaped defected ground structure (DGS) unit is proposed. In contrast to a single finite attenuation pole characteristic offered by the conventional dumbbell DGS, the proposed DGS unit provides dual finite attenuation poles that can be independently controlled by the DGS lengths. A 2.4-GHz microstrip lowpass filter using five cascaded double U-shaped DGS units is designed and compared with conventional DGS lowpass filters. This low pass filter achieves a wide stopband with overall 30-dB attenuation up-to10 GHz and more than 42% size diminution.

Application of Electromagnetic Bandgaps to the Design of Ultra-Wide Bandpass Filters With Good Out-of-Band Performance

Abstract: In this study, a new technique for the design of ultra-wide bandpass filters with spurious suppression over a very wide band is presented. The method consists on the combination of a well-known analytical design approach to achieve wide bandwidths with an electromagnetic bandgap structure, which is fundamental for spurious suppression. To illustrate the technique, a microstrip of ultra-wide bandpass filter centered at 3.4 GHz with a bandwidth covering 4.8 GHz is implemented in an Arlon substrate (permittivity epsivr=2.4, thickness h=0.675 mm). Measured filter characteristics are good with in-band insertion losses below 0.90 dB and return losses better than 10 dB. Out-of-band performance is also good with spurious passband attenuation higher than 30 dB up to at least 20 GHz

Tunable metamaterial transmission lines based on varactor-loaded split-ring resonators

Abstract: In this paper, it is demonstrated that varactor-loaded split-ring resonators (VLSRRs) coupled to microstrip lines can lead to metamaterial transmission lines with tuning capability. Both negative permeability (mu<0) and double (or left-handed) negative media have been designed and fabricated with tuning ranges as wide as 30%. The negative effective permeability is provided by the VLSRRs in a narrow band above their resonant frequency, which can be bias controlled by virtue of the presence of diode varactors. To achieve a negative effective permittivity in the left-handed structure, metallic vias emulating shunt inductances are periodically placed between the conductor strip and the ground plane. The lumped-element equivalent-circuit models of the designed structures have been derived. It has been found that these models provide a good qualitative description of device performance. Since the VLSRR microstrip line and the line loaded with both VLSRRs and vias exhibit stopband and bandpass behavior, respectively, the ideas presented in this study can be applied to the design of narrowband tunable frequency-selective structures with compact dimensions. This is the first time that a tunable left-handed transmission line, based on SRRs, is proposed

Wide-stopband microstrip bandpass filters using dissimilar quarter-wavelength stepped-impedance resonators

Abstract: Wide-stopband and compact microstrip bandpass filters (BPFs) are proposed using various dissimilar quarter-wavelength (/spl lambda//4) stepped-impedance resonators (SIRs) for multiple spurious suppression. The use of /spl lambda//4 SIRs is essential in widening the filter stopband and reducing the circuit size. By properly arranging the individual /spl lambda//4 SIR, which has the same fundamental resonance frequency f/sub 0/, but has different spurious (harmonic) resonance frequencies, and also carefully misaligning the maximum current density nodes, several higher order spurious resonances may be suppressed so that a BPF with wide stopband may be realized. In this study, the basic concept of multiple spurious suppression is demonstrated by thoroughly investigating the spurious characteristics of the fourth-order interdigital BPFs, which consist of two different types of /spl lambda//4 SIRs. To widen the rejection bandwidth, the fourth-order coupled-resonator BPFs based on three and four different types of /spl lambda//4 SIRs are implemented and carefully examined. Specifically, a very wide-stopband microstrip BPF composed of four dissimilar /spl lambda//4 SIRs is realized and its stopband is extended even up to 11.4f/sub 0/ with a rejection level better than 27.5 dB.

Compact Ultra-Wideband Bandpass Filters Using Composite Microstrip&#8211;Coplanar-Waveguide Structure

Abstract: Compact ultra-wideband bandpass filters are proposed based on the composite microstrip-coplanar-waveguide (CPW) structure. In this study, the microstrip-CPW transitions and the CPW shorted stubs are adopted as quasi-lumped-circuit elements for realizing a three-pole high-pass filter prototype. By introducing a cross-coupled capacitance between input and output ports of this high-pass filter and suitably designing the transition stretch stubs, a compact three-pole ultra-wideband bandpass filter is implemented with two transmission zeros located close to the passband edges. To further improve the selectivity, two microstrip shorted stubs are added to implement a five-pole ultra-wideband bandpass filter with good out-of-band response. Being developed from the quasi-lumped elements, and not from the transmission lines, the proposed ultra-wideband filters have sizes more compact than those of the published wideband filters. The proposed ultra-wideband filters have the merits of compact size, flat group delay, good insertion/return loss, and good selectivity. Agreement between simulated and measured responses of these filters is demonstrated

Design of a New Tri-Band Microstrip BPF Using Combined Quarter-Wavelength SIRs

Abstract: A new tri-band microstrip bandpass filter (BPF) is designed to produce three passbands at the commercially practical frequencies through a single piece of filter circuitry. The basic component used to build the proposed filter consists of two quarter-wavelength (lambda/4) stepped-impedance resonators (SIRs). One of the lambda/4 SIRs is designed to operate at 1.57 GHz and 5.25 GHz, and the other at 2.45 GHz. The feed positions for the two lambda/4 SIRs are carefully located to have the same distance from the via-hole ground and meanwhile to give the required external quality factors (Qe's). In such a way, the microstripline sections between the via-hole and each of the feed positions can be combined into one to simplify the filter structure, and to reduce the BPF circuit size. Performance of the newly designed tri-band BPF is verified by measured results

Improved wide-band Schiffman phase shifter

Abstract: In this paper, one improved wide-band Schiffman phase shifter is presented by modifying the ground plane underneath the coupled lines. In this new design, with the ground plane under the coupled lines removed, the even-mode impedance will be increased substantially. Meanwhile, we propose that one additional isolated rectangular conductor is placed under the coupled lines to act as one capacitor so that the odd-mode impedance is decreased. The proposed new design was simulated by the full-wave electromagnetic software IE3D and validated by the measurement. Compared with the cascading microstrip multisection coupled-line configuration, our newly proposed planar one with a patterned ground plane is small in size and, meanwhile, has a good performance. As an example, one Schiffman phase shifter on a double-sided printed circuit board is designed, simulated, fabricated, and measured. The measured amplitude and phase imbalance between the two paths are within 0.5 dB and 5/spl deg/, respectively, over the frequency band from 1.5 to 3.1 GHz, or around 70% bandwidth. The measured return loss is found to be better than -12 dB over the operating frequency band.

A compact single layer monopulse microstrip antenna array

Abstract: A compact single layer monopulse microstrip patch antenna array for the application of monopulse radar has been designed, manufactured and tested. The array, the monopulse comparator and the feed network are placed on the same layer, resulting in a very compact structure. The limitation of this structure is discussed. The effects of spurious radiation and blockage caused by the comparator on the sidelobe level are estimated. A space mapping (SM) technique is applied to design microstrip subarray. The bandwidth (VSWR<2) of the antenna is 5.6%, the operating frequency is between 13.85-15.1 GHz and the designed central frequency is 14.25 GHz. Our measurements show that, both for the E plane and for the H plane, the sidelobe levels of the sum pattern are less than -17 dB, and the null depths of the difference pattern are less than -30 dB. The maximum gain at the operating frequencies is 24.5 dBi.

Compact wide-band branch-line hybrids

Abstract: Wide-band branch-line couplers are designed and tested. The proposed couplers feature compact size on a single circuit layer structure without via-holes. For the broad-band property and cost effectiveness, we have designed a four-branch hybrid with mixed distributed and lumped distributed elements. Analysis on the equivalent circuits was performed carefully in order to obtain a sufficient bandwidth with reduced design area. The fabricated hybrids have the fractional bandwidth larger than 56% at the center frequency of 2 GHz. They also show size reduction up to 55.2% compared with the conventional design method.

Ferrite phase shifter and phase array radar system

Abstract: A phase shifter comprises a substrate, a ground plane formed on a first surface of the substrate, a support structure positioned on a second surface of the substrate opposite the first surface, three parallel, non-co-planar microstrip lines supported by the support structure above the second surface of the substrate, a ferrite element supported by the support structure between the second surface of the substrate and the three non-co-planar microstrip lines, and means for applying a magnetic field to the ferrite element.

Microstrip - Fed Low Profile and Compact Dielectric Resonator Antennas

Abstract: This paper presents a novel broadband, low-profile dielectric resonator antenna using relatively low dielectric constant substrate material. The rectangular DRA is fed with a stepped microstrip feed to ensure efficient coupling. Bandwidths in excess of 17% are obtained. In addition, the paper investigates methods to miniaturize the antenna using metallic strips or patches. Substantial size reduction is demonstrated while maintaining a reasonable bandwidth. Simulations as well as experimental results are presented.

Compact Planar Microstrip Branch-Line Couplers Using the Quasi-Lumped Elements Approach With Nonsymmetrical and Symmetrical T-Shaped Structure

Abstract: A class of the novel compact-size branch-line couplers using the quasi-lumped elements approach with symmetrical or nonsymmetrical T-shaped structures is proposed in this paper. The design equations have been derived, and two circuits using the quasi-lumped elements approach were realized for physical measurements. This novel design occupies only 29% of the area of the conventional approach at 2.4 GHz. In addition, a third circuit was designed by using the same formula implementing a symmetrical T-shaped structure and occupied both the internal and external area of the coupler. This coupler achieved 500-MHz bandwidth while the phase difference between S21 and S31 is within 90degplusmn1deg. Thus, the bandwidth is not only 25% wider than that of the conventional coupler, but occupies only 70% of the circuit area compared to the conventional design. All three proposed couplers can be implemented by using the standard printed-circuit-board etching processes without any implementation of lumped elements, bonding wires, and via-holes, making it very useful for wireless communication systems

Bandwidth Enhancement of Wide-Slot Antenna Fed by CPW and Microstrip Line

Abstract: Two printed wide-slot antennas with square patches within an arc-shape slot are proposed in this letter. They are fed by a coplanar waveguide (CPW) and a microstrip line with almost the same performances. Their impedance bandwidths for $ S_11leq -10~ dB$ are enhanced largely to more than 158%. The radiation patterns are given at 2, 6, and 10 GHz.

Synthesis of dual-band bandpass filters using successive frequency transformations and circuit conversions

Abstract: A novel method is proposed to synthesize dual-band bandpass filters (BPFs) from a prototype low-pass filter. By implementing successive frequency transformations and circuit conversions, a new filter topology is obtained which consists of only admittance inverters and series resonators, and is thereby easy to be realized by using conventional distributed elements. A dual-band BPF with center frequencies of 1.8GHz and 2.4GHz is designed and fabricated using microstrip lines and stubs. The simulated and measured results show a good agreement and validate the proposed theory.

Ku-band MMIC phase shifter using a parallel resonator with 0.18-/spl mu/m CMOS technology

Abstract: A digital 5-bit phase shifter at Ku-band is presented, which is implemented with 0.18-mum RFCMOS technology. n-MOSFET switches and top metal microstrip lines with a first-metal ground allow the phase shifter to have small insertion losses. The proposed 90deg phase shifter utilizing a parallel resonator exhibits broad-band characteristics. All of the circuit components are derived to obtain a minimum phase variation at the operation frequency band. A bridged-T type phase shifter is also analyzed in view of parallel resonance using an ideal equivalent-circuit model. The conditions of the circuit elements are derived in an analytic form, which are used to obtain the broad-band phase characteristics. The fabricated 5-bit phase shifter demonstrates an overall rms phase error less than 12deg from 9 to 15 GHz. Insertion losses of 14.5 dB plusmn 0.5 dB and return losses less than 14 dB are obtained for 32 states at 12 GHz. The proposed 90deg phase shifter has performed a phase shift of 92.3degplusmn3.2deg over 9-15 GHz