Showing papers on "Microstrip published in 2005"
11 Nov 2005
TL;DR: In this paper, the authors define Metamaterials (MTMs) and Left-Handed (LH) MTMs as a class of two-dimensional MTMs.
Abstract: Preface. Acknowledgments. Acronyms. 1 Introduction. 1.1 Definition of Metamaterials (MTMs) and Left-Handed (LH) MTMs. 1.2 Theoretical Speculation by Viktor Veselago. 1.3 Experimental Demonstration of Left-Handedness. 1.4 Further Numerical and Experimental Confirmations. 1.5 "Conventional" Backward Waves and Novelty of LH MTMs. 1.6 Terminology. 1.7 Transmission Line (TL) Approach. 1.8 Composite Right/Left-Handed (CRLH) MTMs. 1.9 MTMs and Photonic Band-Gap (PBG) Structures. 1.10 Historical "Germs" of MTMs. References. 2 Fundamentals of LH MTMs. 2.1 Left-Handedness from Maxwell's Equations. 2.2 Entropy Conditions in Dispersive Media. 2.3 Boundary Conditions. 2.4 Reversal of Doppler Effect. 2.5 Reversal of Vavilov- Cerenkov Radiation. 2.6 Reversal of Snell's Law: Negative Refraction. 2.7 Focusing by a "Flat LH Lens". 2.8 Fresnel Coefficients. 2.9 Reversal of Goos-H anchen Effect. 2.10 Reversal of Convergence and Divergence in Convex and Concave Lenses. 2.11 Subwavelength Diffraction. References. 3 TLTheoryofMTMs. 3.1 Ideal Homogeneous CRLH TLs. 3.1.1 Fundamental TL Characteristics. 3.1.2 Equivalent MTM Constitutive Parameters. 3.1.3 Balanced and Unbalanced Resonances. 3.1.4 Lossy Case. 3.2 LC Network Implementation. 3.2.1 Principle. 3.2.2 Difference with Conventional Filters. 3.2.3 Transmission Matrix Analysis. 3.2.4 Input Impedance. 3.2.5 Cutoff Frequencies. 3.2.6 Analytical Dispersion Relation. 3.2.7 Bloch Impedance. 3.2.8 Effect of Finite Size in the Presence of Imperfect Matching. 3.3 Real Distributed 1D CRLH Structures. 3.3.1 General Design Guidelines. 3.3.2 Microstrip Implementation. 3.3.3 Parameters Extraction. 3.4 Experimental Transmission Characteristics. 3.5 Conversion from Transmission Line to Constitutive Parameters. References. 4 Two-Dimensional MTMs. 4.1 Eigenvalue Problem. 4.1.1 General Matrix System. 4.1.2 CRLH Particularization. 4.1.3 Lattice Choice, Symmetry Points, Brillouin Zone, and 2D Dispersion Representations. 4.2 Driven Problem by the Transmission Matrix Method (TMM). 4.2.1 Principle of the TMM. 4.2.2 Scattering Parameters. 4.2.3 Voltage and Current Distributions. 4.2.4 Interest and Limitations of the TMM. 4.3 Transmission Line Matrix (TLM) Modeling Method. 4.3.1 TLM Modeling of the Unloaded TL Host Network. 4.3.2 TLM Modeling of the Loaded TL Host Network (CRLH). 4.3.3 Relationship between Material Properties and the TLM Model Parameters. 4.3.4 Suitability of the TLM Approach for MTMs. 4.4 Negative Refractive Index (NRI) Effects. 4.4.1 Negative Phase Velocity. 4.4.2 Negative Refraction. 4.4.3 Negative Focusing. 4.4.4 RH-LH Interface Surface Plasmons. 4.4.5 Reflectors with Unusual Properties. 4.5 Distributed 2D Structures. 4.5.1 Description of Possible Structures. 4.5.2 Dispersion and Propagation Characteristics. 4.5.3 Parameter Extraction. 4.5.4 Distributed Implementation of the NRI Slab. References. 5 Guided-Wave Applications. 5.1 Dual-Band Components. 5.1.1 Dual-Band Property of CRLH TLs. 5.1.2 Quarter-Wavelength TL and Stubs. 5.1.3 Passive Component Examples: Quadrature Hybrid and Wilkinson Power Divider. 5.1.3.1 Quadrature Hybrid. 5.1.3.2 Wilkinson Power Divider. 5.1.4 Nonlinear Component Example: Quadrature Subharmonically Pumped Mixer. 5.2 Enhanced-Bandwidth Components. 5.2.1 Principle of Bandwidth Enhancement. 5.2.2 Rat-Race Coupler Example. 5.3 Super-compact Multilayer "Vertical" TL. 5.3.1 "Vertical" TL Architecture. 5.3.2 TL Performances. 5.3.3 Diplexer Example. 5.4 Tight Edge-Coupled Coupled-Line Couplers (CLCs). 5.4.1 Generalities on Coupled-Line Couplers. 5.4.1.1 TEM and Quasi-TEM Symmetric Coupled-Line Structures with Small Interspacing: Impedance Coupling (IC). 5.4.1.2 Non-TEM Symmetric Coupled-Line Structures with Relatively Large Spacing: Phase Coupling (PC). 5.4.1.3 Summary on Symmetric Coupled-Line Structures. 5.4.1.4 Asymmetric Coupled-Line Structures. 5.4.1.5 Advantages of MTM Couplers. 5.4.2 Symmetric Impedance Coupler. 5.4.3 Asymmetric Phase Coupler. 5.5 Negative and Zeroth-Order Resonator. 5.5.1 Principle. 5.5.2 LC Network Implementation. 5.5.3 Zeroth-Order Resonator Characteristics. 5.5.4 Circuit Theory Verification. 5.5.5 Microstrip Realization. References. 6 Radiated-Wave Applications. 6.1 Fundamental Aspects of Leaky-Wave Structures. 6.1.1 Principle of Leakage Radiation. 6.1.2 Uniform and Periodic Leaky-Wave Structures. 6.1.2.1 Uniform LW Structures. 6.1.2.2 Periodic LW Structures. 6.1.3 Metamaterial Leaky-Wave Structures. 6.2 Backfire-to-Endfire (BE) Leaky-Wave (LW) Antenna. 6.3 Electronically Scanned BE LW Antenna. 6.3.1 Electronic Scanning Principle. 6.3.2 Electronic Beamwidth Control Principle. 6.3.3 Analysis of the Structure and Results. 6.4 Reflecto-Directive Systems. 6.4.1 Passive Retro-Directive Reflector. 6.4.2 Arbitrary-Angle Frequency Tuned Reflector. 6.4.3 Arbitrary-Angle Electronically Tuned Reflector. 6.5 Two-Dimensional Structures. 6.5.1 Two-Dimensional LW Radiation. 6.5.2 Conical-Beam Antenna. 6.5.3 Full-Space Scanning Antenna. 6.6 Zeroth Order Resonating Antenna. 6.7 Dual-Band CRLH-TL Resonating Ring Antenna. 6.8 Focusing Radiative "Meta-Interfaces". 6.8.1 Heterodyne Phased Array. 6.8.2 Nonuniform Leaky-Wave Radiator. References. 7 The Future of MTMs. 7.1 "Real-Artificial" Materials: the Challenge of Homogenization. 7.2 Quasi-Optical NRI Lenses and Devices. 7.3 Three-Dimensional Isotropic LH MTMs. 7.4 Optical MTMs. 7.5 "Magnetless" Magnetic MTMs. 7.6 Terahertz Magnetic MTMs. 7.7 Surface Plasmonic MTMs. 7.8 Antenna Radomes and Frequency Selective Surfaces. 7.9 Nonlinear MTMs. 7.10 Active MTMs. 7.11 Other Topics of Interest. References. Index.
3,731 citations
3 Jan 2005
TL;DR: In this paper, the effects of parasitics on the high-frequency performance of 130-nm CMOS transistors are investigated, and a peak f/sub max/ of 135 GHz has been achieved with optimal device layout.
Abstract: This paper describes the design and modeling of CMOS transistors, integrated passives, and circuit blocks at millimeter-wave (mm-wave) frequencies. The effects of parasitics on the high-frequency performance of 130-nm CMOS transistors are investigated, and a peak f/sub max/ of 135 GHz has been achieved with optimal device layout. The inductive quality factor (Q/sub L/) is proposed as a more representative metric for transmission lines, and for a standard CMOS back-end process, coplanar waveguide (CPW) lines are determined to possess a higher Q/sub L/ than microstrip lines. Techniques for accurate modeling of active and passive components at mm-wave frequencies are presented. The proposed methodology was used to design two wideband mm-wave CMOS amplifiers operating at 40 GHz and 60 GHz. The 40-GHz amplifier achieves a peak |S/sub 21/| = 19 dB, output P/sub 1dB/ = -0.9 dBm, IIP3 = -7.4 dBm, and consumes 24 mA from a 1.5-V supply. The 60-GHz amplifier achieves a peak |S/sub 21/| = 12 dB, output P/sub 1dB/ = +2.0 dBm, NF = 8.8 dB, and consumes 36 mA from a 1.5-V supply. The amplifiers were fabricated in a standard 130-nm 6-metal layer bulk-CMOS process, demonstrating that complex mm-wave circuits are possible in today's mainstream CMOS technologies.
786 citations
TL;DR: In this paper, the authors presented a rigorous design of microstrip bandpass filters with a dual-passband response in parallel-coupled and vertical-stacked configurations, where the second resonant frequency can be tuned over a wide range by adjusting its structure parameters.
Abstract: This paper presents a rigorous design of microstrip bandpass filters with a dual-passband response in parallel-coupled and vertical-stacked configurations. Based on resonance characteristics of a stepped impedance resonator (SIR), the second resonant frequency can be tuned over a wide range by adjusting its structure parameters. Emphasis is placed on filter synthesis for simultaneously matching in-band response and singly loaded Q by using tapped input/output couplings for the two designated passbands. Fractional bandwidth design graphs are used to determine proper geometric parameters of each coupled stage when filter specification is given. Realizable fractional bandwidths of the two passbands for a coupled SIR structure are clearly depicted in fractional bandwidth design graphs. Several experimental filters are fabricated and measured to demonstrate the design.
353 citations
12 Jun 2005
TL;DR: In this paper, a composite microstrip bandpass filter (BPF) with a 3 dB fractional bandwidth of more than 100% was designed for ultra wideband (UWB) wireless communications.
Abstract: A new technique is developed for designing a composite microstrip bandpass filter (BPF) with a 3 dB fractional bandwidth of more than 100%. The BPF is suitable for ultra-wideband (UWB) wireless communications. The design utilizes embedding individually designed highpass structures and lowpass filters (LPF) into each other, followed by an optimization for tuning in-band performance. The stepped-impedance LPF is employed to attenuate the upper stopband and quarter-wave short-circuited stubs are used to realize the lower stopband. Two such BPFs are fabricated and measured to demonstrate the performance.
352 citations
TL;DR: In this article, a hybrid microstrip and coplanar waveguide (CPW) structure was proposed for ultra wideband (UWB) bandpass filter (BPF).
Abstract: A novel ultra-wideband (UWB) bandpass filter (BPF) is presented using the hybrid microstrip and coplanar waveguide (CPW) structure. A CPW nonuniform resonator or multiple-mode resonator (MMR) is constructed to produce its first three resonant modes occurring around the lower end, center, and higher end of the UWB band. Then, a microstrip/CPW surface-to-surface coupled line is formed and modeled to allocate the enhanced coupling peak around the center of this UWB band, i.e., 6.85GHz. As such, a five-pole UWB BPF is built up and realized with the passband covering the entire UWB band (3.1-10.6GHz). A predicted frequency response is finally verified by the experiment. In addition, the designed UWB filter, with a single resonator, only occupies one full-wavelength in length or 16.9mm.
338 citations
Patent•
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28 Mar 2005
TL;DR: In this article, a plurality of antenna elements on a dielectric substrate are adapted to launch or receive electromagnetic waves in or from a direction substantially away from either a convex or concave edge of the dielectrous substrate, wherein at least two of the antenna elements operate in different directions.
Abstract: A plurality of antenna elements on a dielectric substrate are adapted to launch or receive electromagnetic waves in or from a direction substantially away from either a convex or concave edge of the dielectric substrate, wherein at least two of the antenna elements operate in different directions. Slotlines of tapered-slot endfire antennas in a first conductive layer of a first side of the dielectric substrate are coupled to microstrip lines of a second conductive layer on the second side of the dielectric substrate. A bi-conical reflector, conformal cylindrical dielectric lens, or discrete lens array improves the H-plane radiation pattern. Dipole or Yagi-Uda antenna elements on the conductive layer of the dielectric substrate can be used in cooperation with associated reflective elements, either alone or in combination with a corner-reflector of conductive plates attached to the conductive layers proximate to the endfire antenna elements.
335 citations
TL;DR: In this article, a defected ground structure (DGS) pattern is proposed to reduce the cross-polarized (XP) radiation of a microstrip patch antenna, which is simple and easy to etch on a commercial microstrip substrate.
Abstract: A defected ground structure (DGS) is proposed to reduce the cross-polarized (XP) radiation of a microstrip patch antenna. The proposed DGS pattern is simple and easy to etch on a commercial microstrip substrate. This will only reduce the XP radiation field without affecting the dominant mode input impedance and co-polarized radiation patterns of a conventional antenna. The new concept has been examined and verified experimentally for a particular DGS pattern employing a circular patch as the radiator. Both simulation and experimental results are presented.
321 citations
TL;DR: In this paper, a circular-disc ring printed on a dielectric substrate and fed by a 50Ω microstrip line is demonstrated numerically and experimentally to achieve an ultra-wide 10dB bandwidth with omnidirectional radiation patterns over the entire bandwidth.
Abstract: This paper presents a novel design of printed circular-ring monopole antennas for ultra-wideband (UWB) applications. A circular-disc ring printed on a dielectric substrate and fed by a 50Ω microstrip line is demonstrated numerically and experimentally to achieve an ultra-wide 10-dB bandwidth with omnidirectional radiation patterns over the entire bandwidth. The design parameters and the performance of the proposed antenna are analyzed. Good agreement has been obtained between the simulation and the measurement. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 45: 372–375, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20827
307 citations
TL;DR: In this article, a dual-band microstrip bandpass filter is proposed and designed to operate at 2.4 and 5.2 GHz without needing any external impedance-matching block, and the modified halfwavelength stepped-impedance resonator with sinuous configuration is constructed to simultaneously excite the dual resonances at these two specified frequencies with miniaturized overall size.
Abstract: A compact dual-band microstrip bandpass filter is proposed and designed to operate at 2.4 and 5.2GHz without needing any external impedance-matching block. The modified half-wavelength stepped-impedance resonator with sinuous configuration is constructed to simultaneously excite the dual resonances at these two specified frequencies with miniaturized overall size. The parallel-coupled microstrip line is properly characterized to minimize the return losses within both dual passbands. The optimized results exhibit the good dual-band filtering performances with return losses higher than 20dB as well being confirmed by experimentation with a fabricated filter circuit.
275 citations
12 Jun 2005
TL;DR: In this paper, an ultra wideband (UWB) bandpass filter using broadside-coupled microstrip-coplanar waveguide structure has been proposed for UWB systems.
Abstract: This paper presented an ultra-wideband (UWB) bandpass filter using broadside-coupled microstrip-coplanar waveguide structure. The filter consists of a microstrip line coupled to a coplanar waveguide (CPW) that was fabricated on the ground of the microstrip line. The proposed filter has been simulated, fabricated and measured for UWB system. The measured results demonstrated the UWB properties from 3.0 GHz to 10.63 GHz (-10 dB bandwidth) and the potential to be wider. A threesection filter shown insertion loss at central frequency is about 0.32 dB and very flat over the whole band. The group delay, which is important to an impulse radio UWB system, is about 0.42 ns over the most central band and less than 0.95 ns over the whole band. The filter also exhibited a good performance outside the band, both at low frequency end (to meet FCC limit) and high frequency end higher than 18 GHz with insertion loss larger than 30 dB.
238 citations
TL;DR: In this article, a new class of sharp-rejection, low insertion-loss wide-band planar filters is presented, where the filtering action comes about through the generation of multiple out-of-band power transmission zeros and constructive in-passband signal combinations.
Abstract: A new class of sharp-rejection, low insertion-loss wide-band planar filters is presented in this letter. The proposed filter topology uses transversal signal-interference filtering sections made up of two transmission-line segments connected in parallel. Thus, under signal-interaction principles, the filtering action comes about through the generation of multiple out-of-band power transmission zeros and constructive in-passband signal combinations. Design equations and guidelines to adjust both the bandwidth and the out-of-band performance of the filtering response through the design parameters of the transversal section are also provided. Furthermore, the theoretical results are validated with the manufacture and characterization of an ultra-wideband microstrip filter prototype at 5 GHz.
TL;DR: In this paper, a dual-band circularly polarized patch antenna dedicated to satellite communications is presented, which is obtained by inserting a small X-band microstrip patch antenna into a large L-band one.
Abstract: This letter presents a dual-band circularly polarized patch antenna dedicated to satellite communications. The dual-band behavior is obtained by inserting a small X-band microstrip patch antenna into a large L-band one. Both patches are printed on the same substrate and fed by electromagnetic coupling through two perpendicular slots etched in their ground planes. These slots are fed by two different 90/spl deg/ microstrip branch-line couplers printed on a stacked lower substrate. A prototype of the antenna was realized with a 1.5-mm-thick upper layer substrate and a 0.758-mm-thick feed layer substrate, both of the same dielectric material with a relative permittivity of /spl epsiv//sub r/=2.22. Simulation and measurement results are presented, showing this compact dual-band antenna achieves the required Meteosat specifications in terms of frequency bandwidth, circular polarization bandwidth, and isolation between the two communication bands.
TL;DR: In this article, a compact wideband high-rejection microstrip bandstop filter (BSF) was proposed, which combines two traditional BSFs: open-stub filter and spurline filter.
Abstract: A compact wideband high-rejection microstrip bandstop filter (BSF) is presented This filter combines two traditional BSFs: open-stub filter and spurline filter Due to the inherently compact characteristics of the spurline, the proposed filter shows a better rejection performance than open-stub BSF without increasing the circuit size From 37 to 54 GHz, the proposed BSF has a rejection of better than 20 dB and the maximum rejection level of 61 dB Application of this BSF to suppress the second harmonic of an open-loop ring bandpass filter is also investigated with a 40-dB suppression improvement achieved
TL;DR: In this paper, a general technique was proposed to compensate these currents and suppress radiation in horizontal directions, where dielectric polarization currents were identified as the physical sources of this radiation.
Abstract: Microstrip (patch) antennas usually strongly radiate in directions along the ground plane. This effect causes unwanted radiation patterns and increased coupling among array elements. Dielectric polarization currents are identified as physical sources of this radiation. A general technique is proposed to compensate these currents and suppress radiation in horizontal directions.
TL;DR: In this article, a planar wideband microstrip balun implemented on a single-layer printed circuit board (PCB) is presented, which consists of a wide-band Wilkinson power divider and a noncoupled-line broad-band 180/spl deg/ phase shifter.
Abstract: A new wide-band microstrip balun implemented on a single-layer printed circuit board (PCB) is presented in this letter. The proposed planar balun consists of a wide-band Wilkinson power divider and a noncoupled-line broad-band 180/spl deg/ phase shifter. To demonstrate the design methodology, one prototype is realized. The new design was simulated and validated by the measurement. Measured results show that 10-dB return loss of the unbalanced port has been achieved across the bandwidth from 1.7 GHz to 3.3 GHz, or 64%. Within the operation band, the measured return losses for both the two balanced ports are better than -10 dB, and the balanced ports isolation is below -1.5 dB. The measured amplitude and phase imbalance between the two balanced ports are within 0.3 dB and /spl plusmn/5/spl deg/, respectively, over the operating frequency band.
TL;DR: In this paper, a branch line coupler using discontinuous microstrip lines whose size is significantly reduced relative to the standard design is introduced. Butler and Gentry manipulate the reactive characteristics of discontinuities in the microstrip line to achieve a physical size reduction of almost 60% with comparable performance.
Abstract: We introduce a branch-line coupler using discontinuous microstrip lines whose size is significantly reduced relative to the standard design. We manipulate the reactive characteristics of discontinuities in its microstrip lines to achieve a physical size reduction of almost 60% with comparable performance.
TL;DR: In this article, the transition between a grounded coplanar waveguide and a substrate integrated rectangular waveguide (SIRW) is investigated and a computer-aided-design-oriented analytical model is developed in order to optimize the geometrical dimensions of the transition.
Abstract: The transition between a grounded coplanar waveguide (GCPW) and a substrate integrated rectangular waveguide (SIRW) is investigated in this paper. The proposed scheme makes use of a current probe to transfer power between the two dissimilar transmission lines. A computer-aided-design-oriented analytical model is developed in order to optimize the geometrical dimensions of the transition. By using the GCPW instead of the microstrip line to interface the SIRW, substrate thickness can be increased without incurring a penalty due to transmission loss. Therefore, it is possible to achieve higher Q components. Experiments at 28 GHz show that an effective bandwidth of 10% can easily be obtained. The insertion loss is less than 0.73 dB over the bandwidth of interest.
TL;DR: In this article, the authors presented the development of tunable filters using ohmic contact microelectromechanical system switches, which is very well suited for the fabrication of low-loss high tuning-range microwave filters.
Abstract: This paper presents the development of tunable filters using ohmic contact microelectromechanical system switches. It is shown that this type of switch is very well suited for the fabrication of low-loss high tuning-range microwave filters. Two sets of tunable Ku-band microstrip filters and resonators have been fabricated, with measured tuning ranges of 20% and 44%, and unloaded quality factors better than 75 in all cases. The 2-bit 5.7% fractional bandwidth, tunable bandpass filters exhibit insertion losses lower than 3.2 dB in all states.
1 Jan 2005
TL;DR: In this paper, a new method of realising RF barcodes is presented using arrays of identical microstrip dipoles capacitively tuned to be resonant at different frequencies within the desired licensed-free ISM bands.
Abstract: A new method of realising RF barcodes is presented using arrays of identical microstrip dipoles capacitively tuned to be resonant at different frequencies within the desired licensed-free ISM bands. When interrogated, the reader detects each dipole's resonance frequency and with n resonant dipoles, potentially 2/sup n/-1 items in the field can be tagged and identified. Results for RF barcode elements in the 5.8 GHz band are presented. It is shown that with accurate centre frequency prediction and by operating over multiple ISM and other license-exempt bands, a useful number of information bits can be realised. Further increase may be possible using ultra-wideband (UWB) technology. Low cost lithographic printing techniques based on using metal ink on low cost substrates could lead to an economical alternative to current RFID systems in many applications.
TL;DR: In this paper, the authors present the design and fabrication of a low-noise fixed-tuned 300-360 GHz sub-harmonic mixer, featuring an anti-parallel pair of planar Schottky diodes fabricated by the University of Virginia and flipchipped onto a suspended quartz-based microstrip circuit.
Abstract: This letter presents the design and fabrication of a low-noise fixed-tuned 300-360-GHz sub-harmonic mixer, featuring an anti-parallel pair of planar Schottky diodes fabricated by the University of Virginia and flip-chipped onto a suspended quartz-based microstrip circuit. The mixer exhibits a double side band (DSB) equivalent noise temperature lower than 900K over 18% of bandwidth (300-360-GHz), with 2 to 4.5mW of local oscillator (LO) power. At room temperature, a minimum DSB mixer noise temperature of 700K and conversion losses of 6.3dB are measured at 330GHz.
TL;DR: In this article, the theoretical performance of reduced size substrate lenses fed by aperture-coupled microstrip patch antennas was investigated in the 47-50 GHz band as a function of their diameter, extension length and dielectric constant.
Abstract: This paper presents the theoretical performance (input impedance, -10 dB return-loss bandwidth, radiation patterns and surface efficiencies) of reduced size substrate lenses fed by aperture-coupled microstrip patch antennas. The diameter of the extended hemispherical homogeneous dielectric (/spl epsiv//sub r,lens/) lenses varies between one and five wavelengths in free-space, in order to obtain radiating structures whose directivity is comprised between 10 and 25 dB. A lot of configurations of lenses are investigated using the finite-difference time-domain methods technique and compared in the 47-50 GHz band as a function of their diameter, extension length and dielectric constant. In particular, the analysis of internal reflections-in time and frequency domains-shows that the latter have potentially a strong influence on the input impedance of small lens antennas, even for low values of /spl epsiv//sub r,lens/(2.2), whereas the usual limit (beyond which anti-reflection coatings are required) is /spl epsiv//sub r,lens/=4. We also demonstrate that the diffraction limit of reduced size lenses is reached for extension lengths varying between 50% and 175% of the extension of synthesized ellipses, depending on the lens material and diameter. Finally, we show that superdirective structures with surface efficiencies reaching 250% can be obtained with small lens diameters, justifying the interest in reduced size lens antennas.
TL;DR: In this article, microstrip coupled-line bandpass filters using a Koch fractal shape are proposed for the first time, and they are fabricated on a liquid crystal polymer (LCP) substrate for Ku-band.
Abstract: In this paper, microstrip coupled-line bandpass filters using a Koch fractal shape are proposed for the first time. These filters are fabricated on a liquid crystal polymer (LCP) substrate for Ku-band. Conventional microstrip coupled-line filters are very popular for RF front ends because they can be fabricated easily. However, their large second harmonic causes the shape of the passband to be asymmetric in the upper band and it worsens the skirt properties. By proper design, the second harmonic of fractal filters can be significantly suppressed through the use of fractal shapes. In this paper, using LCP, the maximum harmonic suppression was almost 42 dB. This type of filter can be used to suppress the second harmonic without any additional devices and regardless of the substrate.
TL;DR: In this article, the dual-frequency properties of a dual annular-ring slot antenna fed by coplanar waveguide (CPW) and microstrip feedline are presented and experimentally studied.
Abstract: The dual-frequency properties of a dual annular-ring slot antenna fed by coplanar waveguide (CPW) and microstrip feedline are presented and experimentally studied. The proposed antenna is constructed by dual concentric annular-ring slots fabricated on FR4 substrate with single feed. The proposed slot antennas have good impedance matching for the two operating frequencies with a frequency ratio ranging about 1.34/spl sim/3.11 and 1.4/spl sim/1.74 can be achieved for CPW-fed and microstrip-fed.
TL;DR: In this article, a broad-band dual-polarized microstrip patch antenna with proximity coupling is presented. But the performance of the proposed antenna is limited by the fact that the antenna can only use one patch.
Abstract: This work presents a novel broad-band dual-polarized microstrip patch antenna, which is fed by proximity coupling. The microstrip line with slotted ground plane is used at two ports to feed the patch antenna. By using only one patch, the prototype antenna yields a bandwidth of 22% and 21.3% at the input port 1 and 2, respectively. The isolation between two input ports is below -34 dB across the bandwidth. Good broadside radiation patterns are observed, and the cross-polar levels are below -21 dB at both E and H planes. Due to its simple structure, it is easy to form arrays by using this antenna as an element.
TL;DR: It is demonstrated that such compact meander dipoles can perform better than previously reported microstrip patch antennas as intraocular elements for a retinal prosthesis.
Abstract: In this work, an extremely compact planar meander line dipole is designed and implemented for use as an intraocular element in a retinal prosthesis. This planar meander dipole antenna exhibits a high degree of current vector alignment and is impedance matched by inducing a current phase reversal along its length. This current phase reversal is induced by a minor offset in feed location which yields a highly directive broadside radiation pattern on this particular planar antenna geometry. This concept is applied in designing and implementing a 6/spl times/6 mm planar compact wire dipole at 1.4 GHz as the intraocular element for the data telemetry link of a retinal prosthesis. Coupling measurements between an external microstrip patch antenna and the intraocular wire dipole are presented and compared with those obtained with intraocular microstrip patch antennas in place of the wire dipole. It is demonstrated that such compact meander dipoles can perform better than previously reported microstrip patch antennas as intraocular elements for a retinal prosthesis.
4 Dec 2005
TL;DR: In this article, an active-integrated leaky-wave antenna with power combining scanning capability is presented, which is integrated with a varactor-tuned high-electron mobility transistor (HEMT) voltage controlled oscillator (VCO) on the same plane.
Abstract: In this paper, an active-integrated leaky-wave antenna with power combining scanning capability is presented This leaky-wave antenna with the novel perpendicular L-shape topology is integrated with a varactor-tuned high-electron mobility transistor (HEMT) voltage controlled oscillator (VCO) on the same plane Changing the VCO frequency, we can control not only the dual-beam scanning angle but also derive the power combining effect with the sum (/spl Sigma/) or difference (/spl Delta/) radiation patterns The power combing effect of difference mode, which is the dual-beam pattern and the sum mode pattern, which is a 3-beam pattern, with the 3rd beam located along the middle direction (45/spl deg/, 135/spl deg/) of the X and Y axes The measured scanning angle is steered over a range of 24-46/spl deg/ for the right beam and 127-148/spl deg/ for the left beam Compared with single microstrip leaky-wave antenna, the L-shape LWAs configuration has the advantages of switchable radiation patterns as the VCO varied from 10GHz to 106GHz
TL;DR: In this paper, the synthesis and optimization of 3D lens antennas at millimeter-mm-wave frequencies was studied theoretically and experimentally at millimeters-wave frequency. But the authors only considered the inverse scattering problem, which transforms the radiation pattern of the primary feed into a desired amplitude-shaped output pattern.
Abstract: The synthesis and the optimization of three-dimensional (3-D) lens antennas, consisting of homogeneous dielectric lenses of arbitrary shape and fed by printed sources, are studied theoretically and experimentally at millimeter(mm)-wave frequencies. The aim of the synthesis procedure is to find a lens profile that transforms the radiation pattern of the primary feed into a desired amplitude shaped output pattern. This synthesis problem has been previously applied for dielectric lenses and reflectors. As far as we know, we propose, for the first time, to adapt and implement it for the design of substrate lens antennas. The inverse scattering problem is solved in two steps. In the first one, the geometry of the 3-D lens is rigorously derived using geometrical optics (GO) principles. The resulting second-order partial-differential equation is strongly nonlinear and is of the Monge-Ampe/spl grave/re (M.A) type. The iterative algorithm implemented to solve it is described in detail. Then, a surface optimization of the lens profile combined with an analysis kernel based on physical optics (PO) is performed in order to comply with the prescribed pattern. Our algorithms are successfully validated with the design of a lens antenna radiating an asymmetric Gaussian pattern at 58.5 GHz whose half-power beamwidth equals 10/spl deg/ in H plane and 30/spl deg/ in E plane. The lens is illuminated by a microstrip 2/spl times/2 patch antenna array. Two lens prototypes have been manufactured in Teflon. Before optimization, the measured radiation patterns are in very good agreement with the predicted ones; nevertheless, the -12 dB side lobes and oscillations appearing in the main lobe evidence a strong difference between the desired and measured patterns. This discrepancy is significantly reduced using the optimized lens.
TL;DR: In this article, the effect of varying the plate width, feed gap height, and feedline width on the impedance bandwidth was examined, and it was shown that for a fixed groundplane size, that optimization of these parameters can yield an impedance bandwidth ratio of 43:1 without using any broadbanding techniques.
Abstract: This paper describes a printed rectangular-plate monopole fed by microstrip line The effect of varying the plate width, feed-gap height, and feedline width on the impedance bandwidth is examined It is shown that for a fixed ground-plane size, that optimization of these parameters can yield an impedance bandwidth ratio of 43:1, without using any broadbanding techniques © 2005 Wiley Periodicals, Inc Microwave Opt Technol Lett 47: 153–154, 2005; Published online in Wiley InterScience (wwwintersciencewileycom) DOI 101002/mop21109
Patent•
23 Feb 2005TL;DR: In this paper, the authors provide all organic fully-packaged miniature bandpass filters, baluns, diplexers, multiplexer, couplers and a combination of the above manufactured using liquid crystalline polymer (LCP) and other multilayer polymer based substrates.
Abstract: The present invention provides all organic fully-packaged miniature bandpass filters, baluns, diplexers, multiplexers, couplers and a combination of the above manufactured using liquid crystalline polymer (LCP) and other multilayer polymer based substrates These devices are manufactured using one or more LCP layers having integrated passive components formed thereon to provide the density and performance necessary for multi-band wireless devices In the designs involving multiple LCP layers, the LCP layers are separated by prepeg layers In accordance with an aspect of the present invention, coplanar waveguide, hybrid stripline/coplanar waveguide and/or microstrip topologies are utilized to form the integrated passive components, and the devices can be mass produced on large area panels at least 18 inches by 12 inches with line widths smaller than 10 um
TL;DR: In this article, the authors developed a model for estimating the amount of common-mode cable current induced by the signal voltage on microstrip trace structures or heatsinks on a printed circuit board.
Abstract: Common-mode currents induced on cables attached to printed circuit boards (PCBs) can be a significant source of unintentional radiated emissions. This paper develops a model for estimating the amount of common-mode cable current that can be induced by the signal voltage on microstrip trace structures or heatsinks on a PCB. The model employs static electric field solvers or closed-form expressions to estimate the effective self-capacitances of the board, trace, and/or heatsink. These capacitances are then used to determine the amplitude of an equivalent common-mode voltage source that drives the attached cables. The model shows that these voltage-driven common-mode cable currents are relatively independent of the cable parameters and the trace or heatsink location when the PCB is small relative to the cable length and to a wavelength.