Showing papers on "Microwave engineering published in 2005"

Computational Electromagnetics for RF and Microwave Engineering

Abstract: The numerical approximation of Maxwell's equations, Computational Electromagnetics (CEM), has emerged as a crucial enabling technology for radio-frequency, microwave and wireless engineering. The three most popular 'full-wave' methods - the Finite Difference Time Domain Method, the Method of Moments and the Finite Element Method - are introduced in this book by way of one or two-dimensional problems. Commercial or public domain codes implementing these methods are then applied to complex, real-world engineering problems, and a careful analysis of the reliability of the results obtained is performed, along with a discussion of the many pitfalls which can result in inaccurate and misleading solutions. The book will empower readers to become discerning users of CEM software, with an understanding of the underlying methods, and confidence in the results obtained. It also introduces readers to the art of code development. Aimed at senior undergraduate/graduate students taking CEM courses and practising engineers in the industry.

Artificial magnetic materials based on the new magnetic particle: Metasolenoid

Abstract: New possibilities to design artificial magnetic materials for microwave frequencies are considered. Such composites can be used in microwave engineering at frequencies where no natural lowloss magnetic materials are available. A new magnetic particle (metasolenoid) formed by a stack of many parallel and very closely spaced single broken loops is proposed and analyzed analytically, numerically, and experimentally. It is shown that the effective permeability can reach reasonably high values over a wide frequency range when using such inclusions.

Planar Microwave Engineering: A Practical Guide to Theory, Measurement and Circuits

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Modern Microwave Circuits

Abstract: Microwave Network Theory. Printed Circuits. Microstrip Patch Antennas. Microstrip Coupled Lines. Microstrip Filters. Microwave Lumped Components. Appendix.

Multiconductor Transmission Lines

Abstract: This article is devoted to the analysis of multiconductor transmission lines (MTLs), a type of structure that is encountered in many applications concerning RF and microwave engineering. Our aim is to provide the reader with a self-contained presentation of the subject; we start by establishing the time-domain equations of multiconductor transmission-line systems and then progress step by step to the final objective of determining the frequency-domain solution to those equations. Matrix techniques are made intense-use in order to permit a compact analysis of the problem. Solutions to MTL equations are presented in two different useful formats. At first we consider a solution in the form of a superposition of natural modes of propagation; later, a relationship between voltages and currents at the MTL structure ports is established by employing a transmission matrix. The analysis presented in this article is not limited to the simple case of uniform line structures, as it also encompasses the important problem of nonuniform MTLs. Keywords: guided-wave propagation; mathematical models; matrix techniques; multiconductor systems; transmission lines

Antenna isolation using grounded microwave elements

Abstract: This invention describes a method for improving antenna isolation in an electronic communication device using grounded RF microwave elements and patterns (structures). According to embodiments of the present invention, the RF microwave element can be implemented as a short-circuited section of a quarter-wavelength long transmission line (such as a stripline), or the RF microwave element can contain a metallic coupler and two thin striplines with different lengths, or the RF microwave element can be implemented using a balun concept.

Direct digital synthesis for enabling next generation RF systems

Abstract: Technology advances in HBT (heterojunction bipolar transistor) circuit complexity and device performance are enabling a new generation of circuits for direct synthesis of waveforms in the microwave and sub-mm-wave regions. This improvement in performance will provide the core technology for a new generation of wideband digital systems to support a broad range of defense and commercial applications ranging from software radio, digital communications and advanced RF sensors. Recent results have produced circuits with demonstrated clock rate above 15 GHz with ultimate performance supporting clock rates in excess of 32 GHz.

Microwave oven and method for optimizing its design characteristics

Abstract: FIELD: microwave engineering; treatment of foodstuff, materials, and parts effectively using microwave energy. ^ SUBSTANCE: phase shifter as one of components designed for matching magnetron and foodstuff chamber is shown to possess greater functional capabilities when used in set of two parallel waveguides. Provision is also made for creating mode of operation in which minimal reflection from empty chamber is attained when the latter is selected according to proposed algorithm. Proposed design of microwave oven is distinguished by optimized characteristics for phase shifter and chamber. Variable easy-to-get-at phase shifter makes it possible to keep watch on cooking process. Method for optimizing design characteristics based on results of simulation is given in description of invention. ^ EFFECT: reduced cooking time, extended service life of oven handling comprehensive range of foodstuff. ^ 8 cl, 28 dwg

Improving antenna isolation using grounded microwave elements

Abstract: This invention describes a method for improving antenna isolation in an electronic communication device using grounded RF microwave elements and patterns (structures). According to embodiments of the present invention, the RF microwave element can be implemented as a short-circuited section of a quarter-wavelength long transmission line (such as a stripline), or the RF microwave element can contain a metallic coupler and two thin striplines with different lengths, or the RF microwave element can be implemented using a balun concept.

Microwave Antennas and Circuits Modeling Using Electromagnetic Field Simulator

Abstract: Electromagnetic field simulators have become a widely used tool in a design process of microwave circuits and systems. A proper usage of electromagnetic (EM) field simulators allows substantial reduction of the design time providing reliable results. In such case the required parameters of the designed circuit can be reached even at the first manufactured prototype in spite of high complexity of the structure. However, EM simulation as a numerical process suffers from systematic and random errors similar to measurement using real equipment. Thus the setting of the EM-field simulator such as a frequency range, mesh properties, usage of PEC and PMC walls etc. has to be done with the highest attention and the simulation results have to be always verified using well-established techniques. The aim of the paper is to demonstrate the selected capability of EM-field simulators with a few examples of antenna and circuit modeling. Also an issue of reliability and simulation errors will be discussed.

Application of sandwich multilayer technology to MICs design

Abstract: The sandwich multilayer technology as applied to design of microwave integrated circuits (MICs) is considered for the first time. Potential benefits for microwave applications are discussed. Implementation of various passive MIC components as sandwich multilayer structures is demonstrated. Design of a miniature bandpass filter and directional couplers for telecommunications is presented.

Single antenna microwave nulling using time-reversal techniques

Abstract: In this paper, we describe a single antenna microwave nulling technique that makes use of time-reversal concepts. The time-domain experiments have shown that by using single antenna and time-reversal technique, we can have focusing as well as nulling at any point in space. We have done experiments at 2.45 GHz in a cylindrical cavity environment. The degree of nulling (or focusing) depends on the multipath components in the channel as well as the bandwidth of the signal. The cavity provides a multipath rich-environment where we can show focusing and nulling by using a relatively small bandwidth compared to free space.

Split rings resonators: key particles for microwave device design

Abstract: In this paper, it is demonstrated that split rings resonators (SRRs) and complementary split rings resonators (CSRRs) are very suitable particles for the design and optimization of microwave devices. Properly coupled to planar transmission lines, they allow for the synthesis of planar microwave filters and other microwave devices. Several examples are provided to demonstrate the potentiality of such resonators. The design of compact devices, based on the small electrical size of SRRs and CSRRs, as well as the elimination of undesired frequencies (spurious) are the foremost applications of these resonators.

Phasor angle definition suitable for intermodulation measurements

Abstract: We describe a method for preserving time-invariant phase determination of nonharmonically related signals. In particular, signals produced by intermodulation are considered. We provide simple examples to illustrate our technique, and show how this method is suitable for intermodulation measurements of nonlinear devices and circuits operating at microwave frequencies.

New design formulas for microstrip transmission lines using high‐dielectric substrate

Abstract: Purpose – Characterisation and use of dielectric materials with high permittivity are one of the most developed areas of research in microwave circuit simulation. This is mainly because of their various applications in VHF/UHF and microwave frequencies (correlators, instrumentation systems, …). The primary virtue of high‐dielectric substrates for microwave circuits is the reduced size. Since the high dielectric microstrip line also exhibit low loss and useful impedance range, this class of circuits will undoubtedly find wide applications in microwave integrated circuitry.Design/methodology/approach – Owing to the complexity of the electromagnetic problem, numerical methods become an indispensable tool for analysis and modeling of electromagnetic structures. They are the basis to set‐up computer‐aided design (CAD) packages. These models must be accurate, reliable, easily extracted and need limited computational requirements. Since there was a demand for a model able to describe these parameters accurately,...

Finite Element Analysis

Abstract: The finite-element method is a numerical procedure for obtaining approximate solutions to boundary value problems. It is a general, preeminent approach to solving a wide variety of problems occurring in engineering practice, including those in RF and microwave engineering. It is a powerful tool in the design and characterization of RF and microwave devices. The popularity of the finite-element method can be ascribed to its ability to model very complex geometries and to deal with a variety of media, including inhomogeneous and anisotropic cases. Moreover, the method yields a very sparse matrix that can be generated, stored and solved efficiently. This article describes the basic principle, the numerical formulation, and some applications of the finite-element method for analysis of electromagnetic problems in RF and microwave engineering. It also briefly discusses some computational aspects and advanced topics associated with the method. Keywords: computational electromagnetics; finite-element method; RF and microwave devices; antennas; scattering

Slotted waveguide antenna array

Abstract: FIELD: microwave engineering; slotted waveguide antenna arrays for radar systems of flying vehicles. ^ SUBSTANCE: proposed low-silhouette slotted waveguide antenna array enabling use of group method for manufacturing its components is, essentially, multilayer waveguide system that has radiating antenna array divided into a number of subarrays and power distribution circuit. Radiating elements of slotted waveguide antenna array are longitudinal slots in wide walls of waveguides. Multilayer waveguide system is, essentially, multilayer structure assembled of alternating interconnected thin conducting plates and conducting bases, the latter being provided with through holes forming waveguide channels, and plates forming wide walls of waveguides are provided with through holes of radiating or coupling elements, or power supply elements. ^ EFFECT: facilitated manufacture, enhanced manufacturing and assembling precision, strength, and yield. ^ 8 cl, 10 dwg

Low Temperature Co‐Fired Ceramic (LTCC) Technology in RF and Microwave Engineering

Abstract: This article outlines the low-temperature cofired ceramic (LTCC) technology, from its historic evolvement to the basics of dielectric material properties and manufacturing process with emphasis on the design concept of multilayer LTCC RF and microwave embedded passive devices and modules A detailed table containing most of commonly seen passive components is provided with layouts of their high-frequency circuit models (Table 4 in the article) Keywords: LTCC; ceramic material; RF circuits; laminated waveguide; microwave circuits

Stabilization of Microwave Amplifiers

Abstract: In this paper the concept of stability, in the design of microwave transistor amplifiers is discussed along with various methods of stabilizing the potentially unstable device. The various techniques are then illustrated with the help of a design example utilizing the parameters of a typical small signal microwave BJT

Effect of transverse nonuniformity of the rf field on the efficiency of microwave sources driven by linear electron beams

Abstract: This paper contains a simple analytical theory that allows one to evaluate the effect of transverse nonuniformity of the rf field on the interaction efficiency in various microwave sources driven by linear electron beams. The theory is, first, applied to the systems where the beams of cylindrical symmetry interact with rf fields of microwave circuits having Cartesian geometry. Also, various kinds of microwave devices driven by sheet electron beams (orotrons, clinotrons) are considered. The theory can be used for evaluating the efficiency of novel sources of coherent terahertz radiation.

Conformal Mapping Techniques

Abstract: Conformal mapping techniques (CMTs) can be applied in the analysis of many engineering applications such as boundary value problems and electromagnetic field problems. This article presents information about the formulation of the potential and flux functions and the most important properties and application procedures of some RF and microwave engineering techniques. Keywords: applications of conformal mapping; Schwart–Christoffel transformation; coplanar transmission lines; CAD in RF and microwave engineering

Electromagnetic modeling and characterization of an optically-controlled microwave phase shifter in GaAs integrated technology

Abstract: A state of the art modeling of microwave photoswitching devices is exposed. A new 3 D electromagnetic modeling allows the design of an optically-controlled microwave phase shifter microwave starting from the traditional circuit of a microwave photoswitch. Measurements of the parameters S of this optically-controlled microwave phase shifter attests the function of this circuit by optical way and highlights the interest of the integration of this new type of microwave phase shifters in systems of antennas arrays. A new optically-controlled microwave phase shifter with a patented structure is under development.

Modular microwave attenuators on power up to 1.2 kW

Abstract: In the report, the block diagram and a design of a powerful modular microwave attenuator is submitted. Power is absorbed by film resistors executed on a basis of beryllium ceramics. Heat removal is air forced. Characteristics and electric parameters of separate modules are given. Developed attenuator is intended for adjustment of radio transmitter blocks.

Controlled power splitter

Abstract: FIELD: high-frequency and microwave engineering. ^ SUBSTANCE: proposed controlled power splitter that can be used in systems where controlled distribution of microwave power between two loads is essential has tee-junction, control circuits, and decoupling capacitors. Each side of tee-junction is, essentially, variable filter whose resistors are formed by series connection of two sections of transmission line through varactor, and control voltage is supplied through resistors. Power splitting is effected by tuning away frequency of one of filters for which purpose control voltage is applied to its varactors. ^ EFFECT: stepless gain control, reduced control power, enhanced speed of control. ^ 1 cl, 7 dwg

Effect of solution nature on properties of flexible microwave absorbers

Abstract: The paper presents microwave properties of flexible electromagnetic shields based on solution-containing knitted linens

Time-domain methods in problems of model synthesis of microwave power compressors

Abstract: Introduction The construction of the exact 'absorbing' conditions [1] has extended substantially the range of rigorously solvable initial boundary-value problems in the electrodynamics of nonsine waves and has allowed us to construct effectively analyzable models of open resonant structures. These structures are the basic electrodynamic objects in many modem microwave devices, in particular, microwave power compressors. The paper is devoted to the analysis of the problems arising in model synthesis of the devices of this kind.