Showing papers on "Microstrip published in 2004"
TL;DR: In this article, a super-compact stopband microstrip structure is proposed, where the frequency gap is produced by an array of complementary split ring resonators (CSRRs), a concept proposed for the first time on the ground plane.
Abstract: In this letter a super-compact stopband microstrip structure is proposed. The frequency gap is produced by an array of complementary split ring resonators (CSRRs)-a concept proposed here for the first time-etched on the ground plane. This behavior is interpreted as due to the presence of a negative effective dielectric permittivity in the vicinity of resonance. The resulting device produces a deep rejection frequency band with sharp cutoff, and a pass band that exhibits very low losses and good matching. Due to the sub-lambda operation of CSRRs, the electrical size of the device is very small.
703 citations
TL;DR: It is shown that, in this line, left-handedness can be achieved without losses over an unlimited bandwidth, from the cutoff of the resulting high-pass filter to infinity, with excellent agreement with theory.
Abstract: A transmission line (TL) approach of left-handed (LH) materials is proposed. The transmission characteristics of an ideal LH-TL are presented, the constitutive parameters of an equivalent LH material are derived and shown to be negative, and some LH-transmission paradoxes are explained. Next, a method to design an artificial LH-TL in the form of an ideal lumped-elements ladder network is described and illustrated with simulation results. It is shown that, in this line, left-handedness can be achieved without losses over an unlimited bandwidth, from the cutoff of the resulting high-pass filter to infinity, with excellent agreement with theory. Finally, a microstrip implementation of the LH line for microwaves, using interdigital capacitors and stub inductors, is demonstrated, with moderate insertion loss and a broad bandwidth of the order of 100%.
558 citations
TL;DR: In this article, the dielectric properties of liquid crystal polymer (LCP) have been investigated for millimeter-wave frequency bands at different LCP substrate thicknesses, and various transmission lines are fabricated on different thicknesses and the loss characteristics are given in decibels per centimeter.
Abstract: Liquid crystal polymer (LCP) is a material that has gained attention as a potential high-performance microwave substrate and packaging material. This investigation uses several methods to determine the electrical properties of LCP for millimeter-wave frequencies. Microstrip ring resonators and cavity resonators are measured in order to characterize the dielectric constant (/spl epsi//sub r/) and loss tangent (tan/spl delta/) of LCP above 30 GHz. The measured dielectric constant is shown to be steady near 3.16, and the loss tangent stays below 0.0049. In addition, various transmission lines are fabricated on different LCP substrate thicknesses and the loss characteristics are given in decibels per centimeter from 2 to 110 GHz. Peak transmission-line losses at 110 GHz vary between 0.88-2.55 dB/cm, depending on the line type and geometry. These results show, for the first time, that LCP has excellent dielectric properties for applications extending through millimeter-wave frequencies.
542 citations
13 Dec 2004
TL;DR: In this article, a metamaterial-based electronically controlled transmission line structure is presented and demonstrated as a novel leaky-wave (LW) antenna with tunable radiation angle and beamwidth functionalities.
Abstract: A metamaterial-based electronically controlled transmission-line structure is presented and demonstrated as a novel leaky-wave (LW) antenna with tunable radiation angle and beamwidth functionalities. This structure is, in essence, a composite right/left-handed (CRLH) microstrip structure incorporating varactor diodes for fixed-frequency voltage-controlled operation. Angle scanning at a fixed frequency is achieved by modulating the capacitances of the structure by adjusting the (uniform) bias voltage applied to the varactors. Beamwidth tuning is obtained by making the structure nonuniform by application of a nonuniform bias voltage distribution of the varactors. A rigorous analysis based on an extension of the CRLH concept is proposed and the corresponding dispersion curves, obtained by equivalent-circuit formulas with LC parameters extracted from full-wave simulation, are shown. A 30-cell LW antenna structure, incorporating both series and shunt varactors for optimal impedance matching and maximal tuning range, is designed. This prototype exhibits continuous scanning capability from 50/spl deg/ to -49/spl deg/ by tuning the bias voltages from 0 to 21 V at 3.33 GHz. A maximum gain of 18 dBi at broadside is also achieved. In addition, it provides half-power beamwidth variation of up to 200% with comparison to the case of uniform biasing. The effect of intermodulation due to the nonlinearity of the varactors is shown to be negligible for antenna applications. The antenna is tested in a 10-Mb/s binary phase-shift keying transmission link and successful recovery of the baseband data is demonstrated.
532 citations
TL;DR: In this paper, a novel composite right/left-handed (CRLH) backward-wave coupled-line directional coupler with arbitrary coupling level and broad bandwidth is presented, explained by even/odd-mode analysis, validated by full-wave simulations, and demonstrated by experiments.
Abstract: A novel composite right-/left-handed (CRLH) backward-wave coupled-line directional coupler with arbitrary coupling level and broad bandwidth is presented, explained by even/odd-mode analysis, validated by full-wave simulations, and demonstrated by experiments. First, the CRLH-transmission-line (CRLH TL) theory is given, and a microstrip implementation of a CRLH TL is described. A simple circuit model is then proposed both for the understanding and design of the coupler. The coupler exhibits very unusual characteristics, such as zero electrical length, imaginary even/odd-mode characteristic impedances, and coupling dependence on even/odd attenuation length (instead of propagation length). Both a quasi-0and 3-dB coupler are demonstrated experimentally. The 3-dB coupler exhibits amplitude balance of /spl plusmn/2 dB over a huge bandwidth of 50% (3.5-5.8 GHz), phase balance of 90/spl deg//spl plusmn/5/spl deg/ from 3.0 to 4.0 GHz and directivity of 20 dB.
522 citations
TL;DR: In this paper, a microstrip patch antenna for communication with medical implants in the 402-405 MHz Medical Implant Communications Services band was designed. And the performance of the antennas to changes in these parameters was undertaken.
Abstract: The objective of this paper is to design a microstrip patch antenna for communication with medical implants in the 402-405-MHz Medical Implant Communications Services band. Microstrip antenna design parameters are evaluated using the finite-difference time-domain method, and are compared to measured results. The effects of shape, length, size, location of feed point and ground point, substrate and superstrate materials, and their thicknesses are evaluated. An extensive study of the performance of the antennas to changes in these parameters was undertaken. The results of this paper provide guidance in the design of implantable microstrip antennas.
474 citations
TL;DR: In this article, a planar distributed periodic structure of microstrip-line and stripline types, which support left-handed (LH) waves is presented and their negative refractive index (NRI) properties are shown theoretically, numerically, and experimentally.
Abstract: Planar distributed periodic structures of microstrip-line and stripline types, which support left-handed (LH) waves are presented and their negative refractive index (NRI) properties are shown theoretically, numerically, and experimentally. The supported LH wave is fully characterized based on the composite right/left-handed transmission-line theory and the dispersion characteristics, refractive indexes, and Bloch impedance are derived theoretically. In addition, formulas to extract equivalent-circuit parameters from full-wave simulation are given. Open (microstrip) and closed (stripline) structures with a 5/spl times/5 mm/sup 2/ unit cell operating at approximately 4 GHz are designed and characterized by full-wave finite-element-method simulations. A 20 /spl times/ 6 unit-cell NRI lens structure interfaced with two parallel-plate waveguides is designed. The focusing/refocusing effect of the lens is observed by both circuit theory and full-wave simulations. Focusing in the NRI lens is also observed experimentally in excellent agreement with circuit theory and numerical predictions. This result represents the first experimental demonstration of NRI property using a purely distributed planar structure.
325 citations
TL;DR: This communication presents a novel linearly polarized pattern reconfigurable microstrip parasitic array that uses four switches to reconfigure the radiation pattern into three variations over a shared 2:1 VSWR bandwidth, and has potential applications in mobile communication devices and large phased antenna arrays.
Abstract: This communication presents a novel linearly polarized pattern reconfigurable microstrip parasitic array. Specifically, this antenna uses four switches (currently copper strips for proof of concept) to reconfigure the radiation pattern into three variations over a shared 2:1 VSWR bandwidth, and has potential applications in mobile communication devices and large phased antenna arrays. Both measured and simulated results of a microstrip parasitic array are provided. The effects of changes in physical dimensions and directions for future work are also discussed.
305 citations
Book•
06 May 2004
TL;DR: In this article, the authors present an analysis and model of ring resonance circuits and their application in the context of filter and filter applications, as well as a comparison of the two types of resonance circuits.
Abstract: Preface.1 Introduction.1.1 Background and Applications.1.2 Transmission Lines and Waveguides.1.3 Organization of the Book.2 Analysis and Modeling of Ring Resonators.2.1 Introduction.2.2 Simple Model.2.3 Field Analyses.2.3.1 Magnetic-Wall Model.2.3.2 Degenerate Modes of the Resonator.2.3.3 Mode Chart for the Resonator.2.3.4 Improvement of the Magnetic-Wall Model.2.3.5 Simplified Eigenequation.2.3.6 A Rigorous Solution.2.4 Transmission-Line Model.2.4.1 Coupling Gap Equivalent Circuit.2.4.2 Transmission-Line Equivalent Circuit.2.4.3 Ring Equivalent Circuit and Input Impedance.2.4.4 Frequency Solution.2.4.5 Model Verification.2.4.6 Frequency Modes for Ring Resonators.2.4.7 An Error in Literature for One-Port Ring Circuit.2.4.8 Dual Mode.2.5 Ring Equivalent Circuit in Terms of G, L, C 352.5.1 Equivalent Lumped Elements for Closed- and Open-Loop Microstrip Ring Resonator.2.5.2 Calculated and Experimental Results.2.6 Distributed Transmission-Line Model.2.6.1 Microstrip Dispersion.2.6.2 Effect of Curvature.2.6.3 Distributed-Circuit Model.References.3 Modes, Perturbations, and Coupling Methods of Ring Resonators.3.1 Introduction.3.2 Regular Resonant Modes.3.3 Forced Resonant Modes.3.4 Split Resonant Modes.3.4.1 Coupled Split Modes.3.4.2 Local Resonant Split Modes.3.4.3 Notch Perturbation Split Modes.3.4.4 Patch Perturbation Split Modes.3.5 Further Study of Notch Perturbations.3.6 Split (Gap) Perturbations.3.7 Coupling Methods for Microstrip Ring Resonators.3.8 Effects of Coupling Gaps.3.9 Enhanced Coupling.3.10 Uniplanar Ring Resonators and Coupling Methods.3.11 Perturbations in Uniplanar Ring Resonators.References.4 Electronically Tunable Ring Resonators.4.1 Introduction.4.2 Simple Analysis.4.3 Varactor Equivalent Circuit.4.4 Input Impedance and Frequency Response of the Varactor-Tuned Microstrip Ring Circuit.4.5 Effects of the Package Parasitics on the Resonant Frequency.4.6 Experimental Results for Varactor-Tuned Microstrip Ring Resonators.4.7 Double Varactor-Tuned Microstrip Ring Resonator.4.8 Varactor-Tuned Uniplanar Ring Resonators.4.9 Piezoelectric Transducer Tuned Microstrip Ring Resonator.References.5 Electronically Switchable Ring Resonators.5.1 Introduction.5.2 PIN Diode Equivalent Circuit.5.3 Analysis for Electronically Switchable Microstrip Ring Resonators.5.4 Experimental and Theoretical Results for Electronically Switchable Microtrip Ring Resonators.5.5 Varactor-Tuned Switchable Microstrip Ring Resonators.References.6 Measurement Applications Using Ring Resonators.6.1 Introduction.6.2 Dispersion, Dielectric Constant, and Q-Factor Measurements.6.3 Discontinuity Measurements.6.4 Measurements Using Forced Modes or Split Modes.6.4.1 Measurements Using Forced Modes.6.4.2 Measurements Using Split Modes.References.7 Filter Applications.7.1 Introduction.7.2 Dual-Mode Ring Bandpass Filters.7.3 Ring Bandstop Filters.7.4 Compact, Low Insertion Loss, Sharp Rejection, and Wideband Bandpass Filters.7.5 Ring Slow-Wave Bandpass Filters.7.6 Ring Bandpass Filters with Two Transmission Zeros.7.7 Pizoeletric Transducer-Tuned Bandpass Filters.7.8 Narrow Band Elliptic-Function Bandpass Filters.7.9 Slotline Ring Filters.7.10 Mode Suppression.References.8 Ring Couplers.8.1 Introduction.8.2 180- Rat-Race Hybrid-Ring Couplers.8.2.1 Microstrip Hybrid-Ring Couplers.8.2.2 Coplanar Waveguide-Slotline Hybrid-Ring Couplers.8.2.3 Asymmetrical Coplanar Strip Hybrid-Ring Couplers.8.3 180- Reverse-Phase Back-to-Back Baluns.8.4 180- Reverse-Phase Hybrid-Ring Couplers.8.4.1 CPW-Slotline 180- Reverse-Phase Hybrid-Ring Couplers.8.4.2 Reduced-Size Uniplanar 180- Reverse-Phase Hybrid-Ring Couplers.8.4.3 Asymmetrical Coplanar Strip 180- Reverse-Phase Hybrid-Ring Couplers.8.5 90- Branch-Line Couplers.8.5.1 Microstrip Branch-Line Couplers.8.5.2 CPW-Slotline Branch-Line Couplers.8.5.3 Asymmetrical Coplanar Strip Branch-Line Couplers.References.9 Ring Magic-T Circuits.9.1 Introduction.9.2 180- Reverse-Phase CPW-Slotline T-Junctions.9.3 CPW Magic-Ts.9.4 180- Double-Sided Slotline Ring Magic-Ts.9.5 180- Uniplanar Slotline Ring Magic-Ts.9.6 Reduced-Size Uniplanar Magic-Ts.References.10 Waveguide Ring Resonators and Filters.10.1 Introduction.10.2 Waveguide Ring Resonators.10.2.1 Regular Resonant Modes.10.2.2 Split Resonant Modes.10.2.3 Forced Resonant Modes.10.3 Waveguide Ring Filters.10.3.1 Decoupled Resonant Modes.10.3.2 Single-Cavity Dual-Mode Filters.10.3.3 Two-Cavity Dual-Mode Filters.References.11 Ring Antennas and Frequency-Selective Surfaces.11.1 Introduction.11.2 Ring Antenna Circuit Model.11.2.1 Approximations and Fields.11.2.2 Wall Admittance Calculation.11.2.3 Input Impedance Formulation for the Dominant Mode.11.2.4 Other Reactive Terms.11.2.5 Overall Input Impedance.11.2.6 Computer Simulation.11.3 Circular Polarization and Dual-Frequency Ring Antennas.11.4 Slotline Ring Antennas.11.5 Active Antennas Using Ring Circuits.11.6 Frequency-Selective Surfaces.11.7 Reflectarrays Using Ring Resonators.References.12 Ring Mixers, Oscillators, and Other Applications.12.1 Introduction.12.2 Rat-Race Balanced Mixers.12.3 Slotline Ring Quasi-Optical Mixers.12.4 Ring Oscillators.12.5 Microwave Optoelectronics Applications.12.6 Metamaterials Using Split-Ring Resonators.References.Index.
298 citations
TL;DR: In this article, a reconfigurable microstrip antenna with switchable polarization sense is proposed, consisting of a corner-truncated square radiating patch, four small triangular conductors, and a microstrip line feed.
Abstract: A novel reconfigurable microstrip antenna with switchable polarization sense is proposed. The proposed antenna has a simple structure, consisting of a corner-truncated square radiating patch, four small triangular conductors, and a microstrip line feed. Using independently biased PIN diodes on the patch, it can produce linear polarization, or left- or right-hand circular polarization according to bias voltages. From the measured results, low cross-polarization levels when operated in the linear state and good axial ratios in the circular state are observed.
294 citations
TL;DR: In this paper, the effect of the geometrical shapes of a defected groundplane structure (DGS) slot on performance of the Hi-Lo microstrip low-pass filter (LPF) was examined.
Abstract: This paper examines the effect of the geometrical shapes of a defected ground-plane structure (DGS) slot on performance of the Hi-Lo microstrip low-pass filter (LPF). A three-pole LPF based on an arrowhead DGS slot has 67% less length as compared to a conventional three-pole LPF. It has insertion loss of 0.5 dB and 15-dB rejection in the stopband up to three times the cutoff frequency.
TL;DR: In this article, the authors report on the results of an investigation into dual-mode operation of microstrip triangular patch resonators and their applications for designing dualmode bandpass filters.
Abstract: In this paper, we report on the results of an investigation into dual-mode operation of microstrip triangular patch resonators and their applications for designing dual-mode bandpass filters. It has been found theoretically that the dual modes can result from the rotation and superposition of a fundamental mode. The characteristics of the dual modes and their mode splitting are described. The applications of this new type of dual-mode microstrip patch resonator in the design of microwave planar filter are presented. A circuit model for operation of this type of filter is proposed. Two- and four-pole filters of this type are demonstrated for the first time. Both theoretical and experimental results are presented.
TL;DR: In this paper, a branch-line coupler that can operate at two arbitrary frequencies is presented. But the proposed circuit also features compact size and planar structure, and explicit design formulas of the proposed dual-band coupler are analytically derived.
Abstract: This paper presents the design of a novel branch-line coupler that can operate at two arbitrary frequencies. The proposed circuit also features compact size and planar structure. Explicit design formulas of the proposed dual-band coupler are analytically derived. Moreover, practical issues such as the realization of branch-line impedance and optimum choice of circuit topologies are addressed. For verification purposes, both simulated and measured results of a microstrip branch-line coupler operating at 900/2000 MHz are included.
TL;DR: In this paper, a dual-mode resonator with square-patch or corner-cut elements located at four corners of a conventional microstrip loop resonator is proposed, where one of these patches or corner cuts is called the perturbation element, while the others are called reference elements.
Abstract: A novel dual-mode resonator with square-patch or corner-cut elements located at four corners of a conventional microstrip loop resonator is proposed. One of these patches or corner cuts is called the perturbation element, while the others are called reference elements. In the proposed design method, the transmission zeros are created or eliminated without sacrificing the passband response by changing the perturbation's size depending on the size of the reference elements. A simple transmission-line model is used to calculate the frequencies of the two transmission zeros. It is shown that the nature of the coupling between the degenerate modes determines the type of filter characteristic, whether it is Chebyshev or elliptic. Finally, two dual-mode microstrip bandpass filters are designed and realized using degenerate modes of the novel dual-mode resonator. The filters are evaluated by experiment and simulation with very good agreement.
TL;DR: In this article, an experimental investigation was conducted on printed wide-slot antennas fed by microstrip lines for wideband applications, and two designs with significantly enhanced impedance bandwidths and improved radiation patterns were obtained.
Abstract: An experimental investigation was conducted on printed wide-slot antennas fed by microstrip lines for wideband applications. Results show that the impedance matching of this kind of antenna is greatly affected by the feed-slot combination and feed gap width, with the slot shape being a main contributor of the radiation characteristics. By properly choosing suitable slot shapes, selecting similar feed shapes and tuning their dimensions, two designs with significantly enhanced impedance bandwidths and improved radiation patterns are obtained.
TL;DR: In this paper, an effective method for suppressing PCB radiation from their power bus over an ultrawide range of frequencies by using metallo-dielectric electromagnetic band-gap structures was introduced.
Abstract: As digital circuits become faster and more powerful, direct radiation from the power bus of their printed circuit boards (PCB) becomes a major concern for electromagnetic compatibility engineers. In such multilayer PCBs, the power and ground planes act as radiating microstrip patch antennas, where radiation is caused by fringing electric fields at board edges. In this paper, we introduce an effective method for suppressing PCB radiation from their power bus over an ultrawide range of frequencies by using metallo-dielectric electromagnetic band-gap structures. More specifically, this study focuses on the suppression of radiation from parallel-plate bus structures in high-speed PCBs caused by switching noise, such as simultaneous switching noise, also known as Delta-I noise or ground bounce. This noise consists of unwanted voltage fluctuations on the power bus of a PCB due to resonance of the parallel-plate waveguiding system created by the power bus planes. The techniques introduced here are not limited to the suppression of switching noise and can be extended to any wave propagation between the plates of the power bus. Laboratory PCB prototypes were fabricated and tested revealing appreciable suppression of radiated noise over specific frequency bands of interest, thus, testifying to the effectiveness of this concept.
TL;DR: In this paper, split ring resonators (SRRs) are used to suppress spurious passband suppression in microstrip coupled line band pass filters by means of split-ring resonators.
Abstract: In this letter, spurious passband suppression in microstrip coupled line band pass filters by means of split ring resonators (SRRs) is demonstrated for the first time. By etching SRRs in the upper substrate side, in close proximity to conductor strip, strong magnetic coupling between line and rings arises at the resonant frequency of SRRs. This inhibits signal propagation in the vicinity of that frequency, allowing the rejection of undesired passbands by properly tuning SRRs. To test this novel technique, we have designed and fabricated two different SSRs-based filters. In one case, the rings have been designed to suppress only the first spurious band, and SRRs have been etched at both sides of the 50-/spl Omega/ access lines. For the other prototype, SRRs have been etched on the active device region (i.e., surrounding the parallel coupled lines) and have been tuned to eliminate the first and second undesired bands. The measured frequency responses for these devices confirm the efficiency of this technique to suppress frequency parasitics, with rejection levels near 40 dBs, leaving the passband unaltered. Since SRRs are small particles (with sub-wavelength dimensions at the resonant frequency), this approach does not add extra area to the final layouts. Moreover, the conventional design methodology of the filters holds.
Proceedings Article•
01 Jan 2004
TL;DR: This paper presents the design of a novel branch-line coupler that can operate at two arbitrary frequencies and features compact size and planar structure and practical issues such as the realization of branch- line impedance and optimum choice of circuit topologies are addressed.
Abstract: This paper presents the design of a novel branch-line coupler that can operate at two arbitrary frequencies. The proposed circuit also features compact size and planar structure. Explicit design formulas of the proposed dual-band coupler are analytically derived. Moreover, practical issues such as the realization of branch-line impedance and optimum choice of circuit topologies are addressed. For verification purposes, both simulated and measured results of a microstrip branch-line coupler operating at 900/2000 MHz are included.
TL;DR: In this paper, the authors developed an ultrawide-band transition from a microstrip line to a double-sided parallel-strip line with 1-30 GHz bandwidth, which has an advantage of easy realization of low-impedance lines.
Abstract: Double-sided parallel-strip lines have been used as a balanced transmission line to feed double-sided printed antennas or to fabricate microwave components such as balanced mixers. In this paper, ultrawide-band transitions from microstrip line to double-sided parallel-strip line are developed with 1-30-GHz bandwidth. New microwave components using double-sided parallel-strip lines are designed with good measured results. The double-sided parallel-strip line has an advantage of easy realization of low-impedance lines, which are important for many component designs.
TL;DR: Thin, broad-band, E-shaped microstrip patch antennas (ESPAs), operating in the 5-6 GHz frequency range, are presented, suitable for WLAN adaptor cards in the PCMCIA format, allowing users of current notebook computers to upgrade to this high-speed wireless standard at a low cost.
Abstract: Thin, broad-band, E-shaped microstrip patch antennas (ESPAs), operating in the 5-6 GHz frequency range, are presented. They are intended for high-speed (IEEE 802.11a, 54 Mb/s) wireless computer local area networks (WLAN) and other wireless communication systems. They are suitable for WLAN adaptor cards in the PCMCIA (also known as PC) format, allowing users of current notebook computers to upgrade to this high-speed wireless standard at a low cost. Importantly, our antennas are thin enough to be accommodated in a PCMCIA card of standard 5-mm thickness, without making the antenna end thicker than the card itself. Two different closely spaced antenna pairs are also presented for diversity. A new ESPA configuration with a microstrip feed is presented for easy integration with microwave transceivers. In all cases, within the two IEEE 802.11a WLAN bands (5.15-5.35 GHz and 5.725-5.825 GHz), the reflection coefficient at the antenna input is <-10 dB and in both antenna pairs, mutual coupling between the two antennas is <-20 dB.
TL;DR: In this article, a defected ground structure (DGS) is applied to design a compact microstrip rat-race hybrid coupler, which can achieve both a significant reduction of size and harmonic signal.
Abstract: In this letter, a defected ground structure (DGS) is applied to design a compact microstrip rat-race hybrid coupler. The proposed structure can achieve both a significant reduction of size and harmonic signal. By embedding the DGS section, it is observed that the resonant frequency of the hybrid coupler is significantly lowered, which can lead to a large amount of size reduction for a fixed frequency operation. Besides, the third harmonic signal is suppressed to -30 dB with respect to a conventional rat-race hybrid coupler. In this case, the measured insertion loss is comparable to that of a conventional hybrid coupler.
TL;DR: In this article, the authors presented a high isolation dual-frequency orthogonally polarized rectangular patch antenna utilizing microstrip feed line integrated with a defected ground structure (DGS).
Abstract: This letter presents a high isolation dual-frequency orthogonally polarized rectangular patch antenna utilizing microstrip feed line integrated with a defected ground structure (DGS) The demonstrated approach results in a significant improvement in port isolation in comparison to a conventional dual-polarized antenna fed by simple microstrip lines Measurements show an improvement of 20 dB in port isolation relative to the conventional antenna, operating at 2 and 25 GHz Image impedance of a microstrip line with DGS is controlled by the DGS geometry without modifying the dimension of the line A 150 /spl Omega/ high impedance line is effectively implemented using a microstrip line with 75 /spl Omega/ line width by incorporating the DGS
TL;DR: In this paper, the simulation and experimental investigations of a printed microstrip slot antenna are presented, which is a quarter wavelength monopole slot cut in the finite ground plane edge, and fed electromagnetically by a microstrip transmission line.
Abstract: This paper presents the simulation and experimental investigations of a printed microstrip slot antenna. It is a quarter wavelength monopole slot cut in the finite ground plane edge, and fed electromagnetically by a microstrip transmission line. It provides a wide impedance bandwidth adjustable by variation of its parameters, such as the relative permittivity and thickness of the substrate, width, and location of the slot in the ground plane, and feed and ground plane dimensions. The ground plane is small, 50 mm/spl times/80 mm, and is about the size of a typical PC wireless card. At the center frequency of 3.00 GHz, its width of 50 mm is about /spl lambda//2 and influences the slot impedance and bandwidth significantly. An impedance bandwidth (S/sub 11/=-10 dB) of up to about 60% is achieved by individually optimizing its parameters. The simulation results are confirmed experimentally. A dual complementary slot antenna configuration is also investigated for the polarization diversity.
TL;DR: In this paper, a varactor-tuned combline bandpass filter using step-impedance microstrip lines is considered so that the absolute passband bandwidth can be maintained nearly constant within the tuning range.
Abstract: In this paper, a varactor-tuned combline bandpass filter using step-impedance microstrip lines is considered so that the absolute passband bandwidth can be maintained nearly constant within the tuning range. The difference between the odd- and even-mode characteristics of the coupled microstrip line makes it difficult to design a tunable bandpass filter with minimum degradation in passband performance. By using step-impedance microstrip lines, couplings between resonators can be controlled so that the constant bandwidth requirement could be satisfied with reasonable design parameter values. Lumped inductors are used for input and output coupling networks. Design equations are derived, and experimental results are compared with theoretical ones based on these equations.
TL;DR: In this paper, it was demonstrated that the resonant frequency of split ring resonators (SRRs) can be tuned using varactor diodes and the resulting particle, which is called a varactor-loaded split-ring resonator (VLSRR), is applied to the design of a tunable notch filter at S-band.
Abstract: It is demonstrated that the resonant frequency of split ring resonators (SRRs) can be tuned using varactor diodes. The resulting particle, which is called a varactor-loaded split ring resonator (VLSRR), is applied to the design of a tunable notch filter at S-band. The device consists on a microstrip transmission line with VLSRRs placed at both sides of the conductor strip. Owing to the proximity of the particles to the line the rings are excited and a transmission notch arises. It is shown that simply using two VLSRRs pairs, rejection levels above 20 dB are achieved in a 0.5 GHz tuning interval centred at 2.85 GHz. The proposed device is the first tunable notch filter based on SRRs.
TL;DR: In this article, a 0.5-m right-hand circularly polarized planar reflectarray antenna is designed using microstrip ring elements of variable rotations to achieve a cophasal beam at broadside.
Abstract: This paper reports a dual frequency dual layer circularly polarized reflectarray operating in the C and Ka bands. A 0.5-m right-hand circularly polarized planar reflectarray antenna is designed using microstrip ring elements of variable rotations to achieve a cophasal beam at broadside. The microstrip ring elements are more compact than the traditional reflectarray elements and can minimize blockage for the multilayer multifrequency applications. The highest efficiencies measured are 46% at 7.3 GHz and 38% at 31.75 GHz. The tested cross-polarization levels are -21 dB at 7.3 GHz and -29.2 dB at 31.75 GHz at the broadside direction. The tested results show that the designed ring element is suitable for both the single and dual layer applications with good bandwidth and circularly polarized performance.
TL;DR: A backward directional coupler, composed of a conventional microstrip (C/spl mu/S) line and composite right/left-handed (CRLH) line, is proposed in this article.
Abstract: A novel backward directional coupler, composed of a conventional microstrip (C/spl mu/S) line and composite right/left-handed (CRLH) line, is proposed. This coupler is functionally backward but it is based on a forward-type coupling phenomenon. The coupler is shown to exhibit broad bandwidth and tight coupling characteristics. The theoretical circuit-model results are supported by full-wave and experimental evidence. A quasi 0-dB prototype with more than 50% bandwidth is demonstrated.
TL;DR: In this paper, a periodic microstrip leaky-wave antenna based on composite right/left-handed (CRLH) metamaterials is presented, which includes varactors modulating the capacitive loading of the unit cell and therefore the propagation constant of the structure, resulting in voltage scanning of the radiated beam.
Abstract: A novel electronically scanned periodic microstrip leaky-wave (LW) antenna based on the concept of composite right/left-handed (CRLH) metamaterials is presented. This antenna includes varactors modulating the capacitive loading of the unit cell and therefore the propagation constant of the structure, which results in voltage scanning of the radiated beam. An accurate circuit model is proposed. The antenna is demonstrated experimentally to exhibit continuous scanning in the dominant mode from backward to forward angles. The scanning range is from -10/spl deg/ at 35 V to +7.5/spl deg/ at 0 V, and broadside occurs at 9 V, at the fixed frequency of 3.23 GHz.
TL;DR: In this article, parallel coupled microstrip sections with a slotted ground plane are proposed as building blocks of coupled-line microstrip filters with enhanced performance, which relaxes tolerances of strip width and spacing in those cases where tightly coupled high-impedance sections are required.
Abstract: Parallel coupled microstrip sections with a slotted ground plane are proposed as building blocks of coupled-line microstrip filters with enhanced performance. It is shown that, by proper adjustment of the ground-plane slot dimensions, the double frequency spurious band associated with unequal even/odd electrical lengths can be suppressed or meaningfully reduced. As an additional feature, this simple design relaxes tolerances of strip width and spacing in those cases where tightly coupled high-impedance sections are required. A rough preliminary design can be obtained within a few seconds using a fast optimization algorithm based on a quasi-TEM analysis of the coupled sections. Fine tuning is based on the use of a commercial electromagnetic simulator. Finally, experimental check of filter performance is provided.
TL;DR: In this paper, a 1-dimensional (1-D) periodic defected ground structure (DGS) for microstrip line is presented, and two improved periodic DGS circuits are designed, fabricated, and measured.
Abstract: A novel one-dimensional (1-D) periodic defected ground structure (DGS) for microstrip line is presented in this letter. Different from the periodic DGS with uniform square-patterned defects, the improved periodic DGS has a compensated microstrip line and the dimensions of the square defects are nonuniform and varied proportionally to the relative amplitudes distribution of the exponential function e/sup 1/n/ (n denotes the positive integer). A uniform periodic DGS circuit and two improved periodic DGS circuits are designed, fabricated, and measured. Measurements show that the latter exhibit more excellent performances by suppressing ripples and enlarging stopband bandwidth.