Showing papers on "Microstrip published in 2003"

Novel microwave devices and structures based on the transmission line approach of meta-materials

Abstract: This paper is composed of two parts. In the first part, the fundamentals of ideal transmission lines (TL) meta-materials (NM) with their physical characteristics and the synthesis of practical artificial TL-MMs with their circuital characteristics are presented. A microstrip implementation of a composite right/left handed (CRLH) TL is shown. In the second part, several novel applications based on the theory of the first part are demonstrated: a backfire-to-endfire leaky wave antenna, a coupled-line coupler with arbitrary coupling, a compact enhanced-bandwidth hybrid ring, a dual-band inharmonic branch-line coupler and a negative reflection/refraction phase-conjugating array interface.

Microstrip stepped impedance resonator bandpass filter with an extended optimal rejection bandwidth

Abstract: Bandpass filters with an optimal rejection bandwidth are designed using parallel-coupled stepped impedance resonators (SIRs). The fundamental (f/sub o/) and higher order resonant harmonics of an SIR are analyzed against the length ratio of the high-Z and low-Z segments. It is found that an optimal length ratio can be obtained for each high-Z to low-Z impedance ratio to maximize the upper rejection bandwidth. A tapped-line input/output structure is exploited to create two extra transmission zeros in the stopband. The singly loaded Q(Q/sub si/) of a tapped SIR is derived. With the aid of Q/sub si/, the two zeros can be independently tuned over a wide frequency range. When the positions of the two zeros are purposely located at the two leading higher order harmonics, the upper rejection band can be greatly extended. Chebyshev bandpass filters with spurious resonances up to 4.4f/sub o/, 6.5f/sub o/, and 8.2f/sub o/ are fabricated and measured to demonstrate the idea.

Novel zeroth-order resonance in composite right/left- handed transmission line resonators

Abstract: A novel resonator using a composite right/left-handed (CRLH) transmission line (TL) is presented and its extraordinary resonant characteristics with an infinite-wavelength wave are discussed. The resonance corresponds to the zeroth-order on the analogy of the conventional mode numbering. The zeroth-order resonant characteristics and loss mechanism are fully described by the circuit theory and it is shown that the resonant frequency of the zeroth-order resonator (ZOR) is independent of the physical length so that the resonator can be arbitrarily small under the condition that sufficient reactance is squeezed in a small length. Full-wave simulations and experiments for meta-structured ZORs implemented with the microstrip line technology agree well with the theoretical results and hence the validity of the theory is confirmed. A 61% size reduction from the conventional resonator with a good unloaded Q of 250 is obtained for a prototype ZOR made of 1.5-cell CRLH TL at 1.9GHz in the experiment.

Compact elliptic-function low-pass filters using microstrip stepped-impedance hairpin resonators

Abstract: A compact elliptic-function low-pass filter using microstrip stepped-impendance hairpin resonators and their equivalent-circuit models are developed. The prototype filters are synthesized from the equivalent-circuit model using available element-value tables. To optimize the performance of the filters, electromagnetic simulation is used to tune the dimensions of the prototype filters. The filter using multiple cascaded hairpin resonators provides a very sharp cutoff frequency response with low insertion loss. Furthermore, to increase the rejection-band bandwidth, additional attenuation poles are added in the filter. The filters are evaluated by experiment and simulation with good agreement. This simple equivalent-circuit model provides a useful method to design and understand this type of filters and other relative circuits.

A broad-band dual-polarized microstrip patch antenna with aperture coupling

Abstract: In this communication, a dual-polarized aperture-coupled microstrip patch antenna with a broad-bandwidth high-isolation low cross-polarization levels, and low-backward radiation levels is designed and its features are presented. For broad bandwidth and easy integration with active circuits, it uses the aperture-coupled stacked patches. The corner feeding of square microstrip patches is applied and the coupling aperture is the H-shaped aperture. The theoretical analysis is based on the finite-difference time-domain (FDTD) method. A dual-polarized antenna is designed, fabricated, and measured. The measured return loss exhibits an impedance bandwidth of over 24.4% and the isolation is better than 30 dB over the bandwidth. The cross-polarization levels in both E and H planes are better than -23 dB. The front-to-back ratio of the antenna radiation pattern is better than 22 dB. Both theoretical and experimental results for S parameters and radiation patterns are presented and discussed.

Design of small-size wide-bandwidth microstrip-patch antennas

Abstract: Several designs for small-size wide-bandwidth microstrip antennas are examined through simulation and experiment. Designs are presented based on two wideband patch antennas: the U-slot patch antenna, and the L-probe-fed patch antenna. Several techniques are utilized to reduce the resonant length of these wideband microstrip-patch antennas: increasing the dielectric constant of the microwave substrate material, the addition of a shorting wall between the conducting patch and the ground plane, and the addition of a shorting pin between the conducting patch and the ground plane. Simulation and experimental results confirm that the size of the antennas can be reduced by as much as 94%, while maintaining impedance bandwidths in excess of 20%.

Parallel-coupled microstrip filters with over-coupled end stages for suppression of spurious responses

Abstract: In a parallel-coupled microstrip filter, end stages with over-coupling are designed to suppress the unwanted responses at twice the passband frequency (2f/sub 0/). The inherent transmission zero of an over-coupled input/output stage is shown tunable. It is found that increasing the image impedance of the filter sections can further enhance the suppression. The designed bandpass filters thus have a wide upper stopband and improved passband response symmetry. Measured results of fabricated circuits show that the idea works very well.

Development of substrate integrated waveguide power dividers

Abstract: Two classes of substrate integrated waveguide (SIW) power divider are presented, namely, Y- and T-types. Using arrays of via, the SIW power dividers and microstrip transitions are integrated on the same substrate. Design models are presented respectively for the Y- and T-junctions. Experimental results over the Ka band are given for both structures. The Y-junction shows a bandwidth of 25.2% at -18.5 dB while the T-junction shows a bandwidth of 10.2% at -19.0 dB.

Input/output coupling structure for dielectric waveguide resonator

Abstract: Disclosed is an input/output coupling structure for a dielectric waveguide resonator to be mounted on a printed circuit board, which comprises; a region defined in the printed circuit board and surrounded by a first conductive film formed on the front surface of the printed circuit board and connected to a microstrip line on the printed circuit board, a second conductive film formed on the back surface of the printed circuit board, and a conductive wall connecting the respective peripheries of the first and second conductive films; a first slot formed in the front surface of the region; and a second slot formed in a surface of the dielectric waveguide resonator which is disposed to be opposed to the region of the printed circuit board. The first and second slots are adapted to be disposed in opposed relation to one another. The coupling structure can achieve the connection between a dielectric waveguide resonator and a microstrip line without forming any input/output electrode on the resonator, to facilitate the application of the dielectric waveguide resonator to an electronic circuit even if it is intended to be used in millimetric-wave band.

Low-power microwave plasma source based on a microstrip split-ring resonator

Abstract: Microplasma sources can be integrated into portable devices for applications such as bio-microelectromechanical system sterilization, small-scale materials processing, and microchemical analysis systems. Portable operation, however, limits the amount of power and vacuum levels that can be employed in the plasma source. This paper describes the design and initial characterization of a low-power microwave plasma source based on a microstrip split-ring resonator that is capable of operating at pressures from 0.05 torr (6.7 Pa) up to one atmosphere. The plasma source's microstrip resonator operates at 900 MHz and presents a quality factor of Q=335. Argon and air discharges can be self-started with less than 3 W in a relatively wide pressure range. An ion density of 1.3/spl times/10/sup 11/ cm/sup -3/ in argon at 400 mtorr (53.3 Pa) can be created using only 0.5 W. Atmospheric discharges can be sustained with 0.5 W in argon. This low power allows for portable air-cooled operation. Continuous operation at atmospheric pressure for 24 h in argon at 1 W shows no measurable damage to the source.

RF module and mode converting structure and method

Abstract: The present invention is directed to enable mode conversion between a TEM mode and another mode to be performed among a plurality of waveguides. An RF module comprises: a microstrip line as a first waveguide for propagating electromagnetic waves in a TEM mode; and a waveguide having a multilayer structure as a second waveguide connected to the first waveguide, for propagating electromagnetic waves in another mode different from the TEM mode. An end of the first waveguide is directly or indirectly connected so as to be conductive to one of ground electrodes of the second waveguide from the direction orthogonal to the stacking direction of the ground electrodes. Since magnetic fields are coupled so that the direction of the magnetic field of the first waveguide and that of the magnetic field of the second waveguide match with each other in the E plane, mode conversion between the TEM mode and another mode to be excellently performed between the waveguides.

On the design of novel compact broad-band planar filters

Abstract: On the basis of impedance steps and coupled-line sections as inverter circuits, novel wide-band and very compact filters are presented. The application of alternately high- and low-impedance lines presented to the connected transmission-line resonators partly reduces their lengths to a quarter-wavelength only. In addition, effective techniques are demonstrated to reduce spurious stopband resonance resulting from a remaining half-wavelength resonator. Both suspended stripline (SSL) and microstrip filters were designed, fabricated, and tested, proving this concept in an excellent way. For the prototype filters, center frequencies around 6 GHz were selected. Bandwidths are between 2.5-3.25 GHz, and insertion-loss amounts to around 0.25 dB for the microstrip filters and 0.5 dB (including the transitions to coaxial line) for the SSL filters, respectively. For the selected center frequency and on a substrate with a dielectric constant of 10.8, the smallest microstrip filter is only 15 mm/spl times/5 mm in size.

Packaged electronic components for producing a sub-harmonic frequency signal at millimetric frequencies

Abstract: The invention relates to millimetric packaged electronic components for applications at high frequencies greater than 45 GHz. According to the invention, to facilitate the design of a system including MMIC chips working at these frequencies, it is proposed to use packages containing one or more chips, these packages making it possible to work at these frequencies and including two types of port: a port with transition by contactless electromagnetic coupling providing a connection with an antenna at the high working frequency F via a waveguide; and a port with microstrip or coaxial line type transition enabling a connection at a subharmonic frequency F/N (preferably N=6 or 4 or, if necessary, 3) of the working frequency.

An affordable millimeter-wave beam-steerable antenna using interleaved planar subarrays

Abstract: Design and fabrication aspects of an affordable planar beam steerable antenna array with a simple architecture are considered in this paper. Grouping the elements of a phased array into a number of partially overlapped subarrays and using a single phase shifter for each subarray, generally results in a considerable reduction in array size and manufacturing costs. However, overlapped subarrays require complicated corporate feed networks and array architectures that cannot be easily implemented using planar technologies. In this paper a novel feed network and array architecture for implementing a planar phased array of microstrip antennas is presented that enables the fabrication of low-sidelobe, compact, beam-steerable millimeter-wave arrays and facilitates integration of the RF front-end electronics with the antenna structure. This design uses a combination of series and parallel feeding schemes to achieve the desired array coefficients. The proposed approach is used to design a three-state switched-beam phased array with a scanning width of /spl plusmn/10/spl deg/. This phased array which is composed of 80 microstrip elements, achieves a gain of >20 dB, a sidelobe level of 6.3% for all states of the beam. The antenna efficiency is measured at 33-36% in X band. It is shown that the proposed feeding scheme is insensitive to the mutual coupling among the elements.

Microwave Circuit Modeling Using Electromagnetic Field Simulation

Abstract: CAD development numerical electromagnetics alternative classifications - 2D, 2.5D, 3D solvers frequency domain, time domain, Eigensolver moment method simulators guide and spatial wavelength validation structures meshing and convergence calibration structures de-embedding finite element method simulators FDTD and TLM simulators ports and de-embedding computing impedance multilayer printed circuit boards connectors backward wave couplers microstrip filters choosing the right software.

On the behavior of Koch island fractal boundary microstrip patch antenna

Abstract: The properties of the Koch island fractal boundary microstrip patch antenna are presented. The behavior at the fundamental mode and the existence of high-order modes that exhibit localized current density distributions is discussed. The main features are the size reduction of the patch resonating at the fundamental frequency when compared to Euclidean-shaped patches, and the application of localized modes in designing microstrip patch antennas with directive patterns.

Designing a 161-element Ku-band microstrip reflectarray of variable size patches using an equivalent unit cell waveguide approach

Abstract: We present an equivalent unit cell waveguide approach (WGA) to designing a multilayer microstrip reflectarray of variable size patches. A normal incidence of a plane wave on an infinite periodic array of radiating elements is considered to obtain reflection coefficient phase curves for the reflectarray's elements. It is shown that this problem is equivalent to the problem of reflection of the dominant TEM mode in a waveguide with patches interleaved by layers of dielectric. This waveguide problem is solved using a field matching technique and the method of moments (MoM). Based on this solution, a fast computer algorithm is developed to generate reflection coefficient phase curves for a multilayer microstrip patch reflectarray. The validity of the developed algorithm is tested against alternative approaches and Agilent high frequency structure simulator (HFSS). Having confirmed the validity of the WGA approach, a small offset feed two-layer microstrip patch array is designed and developed. This reflectarray is tested experimentally and shows good performance.

Wideband coplanar waveguide RF probe pad to microstrip transitions without via holes

Abstract: A novel via-less coplanar waveguide (CPW) to microstrip transition is discussed and design rules based on simulations and experimental results are presented. This transition demonstrates a maximum insertion loss of 1 dB over the frequency range from 10 GHz to 40 GHz with a value of 0.4 dB at 20 GHz. This transition could find a variety of applications due to its compatibility with RF systems-on-a chip, low loss performance, low cost and its ease of fabrication.

Reconfigurable bandpass filter with a three-to-one switchable passband width

Abstract: A reconfigurable bandpass filter is described that aims to preserve the optimal performance of a broad-band system under changing signal conditions. It does so by allowing the passband width of the system's receiver to adapt. The filter can be switched between two discrete states with widely differing bandwidths of 500 and 1500 MHz, respectively, while keeping the passband responses centered at 10 GHz. The physical implementation comprises a hybrid-integrated microstrip circuit on a 0.010-in-thick quartz substrate. The circuit employs commercial beam-lead p-i-n diodes to switch fixed-valued reactance elements. Despite the presence of semiconductor switching devices, the filter behaves very linearly, exhibiting measured passband third-order output-referenced intercept points that exceed 46 dBm in both switched states.

The Modeling, Characterization, and Design of Monolithic Inductors for Silicon RF IC's

Abstract: The results of a comprehensive investigation into the characteristics and optimization of Inductors fabricated with the top-level metal of a submicron silicon VLSI process are presented. A computer program which extncts a physics-based model of microstrip components that is suitable for circuit (SPICE) simulation has been used to evaluate the effect of variations in melallization, layout geometry, and substrate parameters upon monolithic inductor performance. Three-dimensional (3-D) numerical simulations and experimental measurements of inductors were also used to benchmark the model aecuncy. It is shown in this work that low inductor Q is primarily due to the restrictions imposed by the thin interconnect metallization available in most very large scale integration (VLSI) technolocies, and that computer optimization of the inductor layout can be used to achieve a 50% improvement in component Q-factor over unoptimized designs.

Real-time spectrum analysis in microstrip technology

Abstract: We report on a time-domain analog in microwave lines to the spatial Fraunhofer (far-field) diffraction in paraxial conditions. Microstrip lines are used to design filtering configurations acting as spectrum analyzers. They are based on linearly chirped distributed Bragg coupling between the fundamental microstrip mode and the same but counterpropagating mode. Linearly chirped continuous impedance modulation in a microstrip line with varying upper plane strip-width is shown to yield a mode-coupling location and group delay linearly distributed in frequency. Under the condition of a temporal equivalent to the spatial Fraunhofer inequality, the energy spectral density of the input signal is directly recoverable from the average output (reflected) power. It is only necessary to take into account a linear axis-change, given by the dispersion coefficient (group-delay slope) of the structure, from time to Fourier frequency. Both pulsed and nonpulsed RF signals are studied. Sequential time-gated segments of the input have to be processed in the nonpulsed case. The maximum frequency resolution achievable in this situation is discussed. The devices developed here could have important potential applications in the field of temporal signal processing, such as filtering using time-division techniques.

Wide band four-port butler matrix for switched multibeam antenna arrays

Abstract: This paper presents the design and realization of a wide band four-port microstrip matrix to feed a switched-beam antenna array for wireless applications at 1.9 GHz. The objective of this investigation is to develop an antenna-array feeding network based on Butler with a large bandwidth in order to cover the PCS band: 1900 MHZ to 2200 MHZ. In order to meet these requirements, wide band microwave components such as hybrids and crossovers were designed and used to Butler proposed matrix. The Butler matrix is used as a beamforming network that allows to produce orthogonal beams that can be steered in different directions. To examine the performance of the proposed matrix, simulated and experimental results is presented and discussed.

Design optimisation of ring elements for broadband reflectarray antennas

Abstract: Plane wave scattering from a flat surface consisting of two periodic arrays of ring elements printed on a grounded dielectric sheet is investigated. It is shown that the reflection phase variation as a function of ring diameter is controlled by the difference in the centre resonant frequency of the two arrays. Simulated and measured results at X-band demonstrate that this parameter can be used to reduce the gradient and improve the linearity of the reflection phase versus ring size slope. These are necessary conditions for the re-radiating elements to maximise the bandwidth of a microstrip reflectarray antenna. The scattering properties of a conventional dual resonant multilayer structure and an array of concentric rings printed on a metal backed dielectric substrate are compared and the trade-off in performance is discussed.

Circularly polarized single-fed wide-band microstrip patch

Abstract: For more than 25 years, the circularly polarized single-fed microstrip patch was considered to be extremely narrow-band. The reported performances are almost exclusively related to single patches printed on a dielectric substrate, which partially explains the frequency characteristics. The antenna proposed is a variation of the "almost square" patch and exhibits measured axial radio of less than 2.5 dB over a 13% bandwidth. The antenna was designed for wireless applications.

Waveguide-to-microstrip transition with integrated bias-T

Abstract: A novel device, a waveguide-to-microstrip transition with an integrated bias-T, is presented. The substrate-based planar structure comprises a waveguide E-probe, shaped as a radial line. The probe couples the RF field of a full-height waveguide to a microstrip line or directly to an active component, e.g., a transistor or diode in a mixer or direct detector. The radial probe is connected on its wide side to another port via a specially shaped high impedance line that provides RF/DC isolation. This port can then be used to inject DC and/or extract IF signals. The design of the presented structure was done using CAD (3-D EM simulation) and an X-band device was produced and fully characterized. The measured performance is in excellent agreement with the simulations; the device has return loss better than -20 dB, insertion loss less or equal to -0.15 dB and isolation for the bias-T line better than -20 dB. RF bandwidth for the transition is 30% of the central frequency.

Microstrip conductor loss models for electromagnetic analysis

Abstract: This paper describes and rigorously validates single- and multiple-layer models of microstrip conductor loss appropriate for high-accuracy application in electromagnetic analysis software. The models are validated by comparison with measurement and by comparison with converged results. It is shown that in some cases an extremely small cell size is needed in order to achieve convergence. Several effects that make a significant contribution to loss and are not modeled by the classic square root of frequency loss model are investigated including dispersion and current on the side of transmission lines. Finally, the counterintuitive result that there is an optimum metal thickness for minimum planar conductor loss is explored.

Permittivity characterization of low-k thin films from transmission-line measurements

Abstract: Developed a broad-band technique for measuring the relative permittivity of low-k thin films using microstrip transmission-line measurements. From measurements of the complex microstrip propagation constant and the characteristic impedance, we determined the relative permittivity of thin films incorporated in microstrip lines. We present measurement results to 40 GHz for both an oxide and a bisbenzocyclobutene low-k thin film and show a variability of permittivity of approximately /spl plusmn/5% over the entire frequency range.

Broadband tapered microstrip leaky-wave antenna

Abstract: This study proposes a novel scheme based on the characteristics of leaky-wave antennas for the empirical design of broadband tapered microstrip leaky-wave antennas. This scheme can explain and approximately model the radiation characteristics of a linearly tapered leaky-wave microstrip antenna. A broadband feeding structure that uses the balanced and the inverted balanced microstrip lines to form a pair of broadband baluns is also presented. The measured return loss of the inverted balanced microstrip lines has a VSWR/spl les/2 from dc to 18.6 GHz and that of the back-to-back feeding structures has a VSWR/spl les/2 from 2.2 to 18.6 GHz. This feeding structure can be used to feed a broadband planar leaky-wave antenna with a fixed mainbeam that uses the tapered microstrip structure. The measured bandwidth of the antenna for a VSWR/spl les/2 exceeds 2.3:1.

A novel bi-directional amplifier with applications in active Van Atta retrodirective arrays

Abstract: A novel two-port bi-directional amplifier, which may simultaneously amplify the waves coming from both ports, is proposed and demonstrated in this paper Using this amplifier, a two-element active Van Atta retrodirective array is implemented and compared to a four-element passive array The bi-directional amplifier is constructed by two identical one-port reflection-type amplifiers and a 3-dB 90/spl deg/ hybrid The reflection-type amplifier is designed using an FET with a single-power-supply configuration A quarter-wavelength microstrip radial stub is connected to the device's source terminal to narrow down the negative-resistance frequency range so as to avoid oscillation at undesired frequencies The fabricated bi-directional amplifier provides the transmission gain over the frequency band from 576 to 688 GHz, with a peak value of 91 dB at 604 GHz Printed Yagi antennas with four directors are adopted to build both the active and passive Van Atta arrays The 3-dB back-scattering beamwidth of the active array is measured as wide as 74/spl deg/ Finally, it is observed from the measurements that, although only half of the antenna elements are used, the active Van Atta array produces a back-scattering field level 45 dB, on average, higher than the passive one does This verifies the performance of the bi-directional amplifier