Microwave Circuit Design Research Articles

Design of C-Band Microstrip Patch Antenna for Radar Applications Using IE3D

In the recent years the development in communication systems requires the development of low cost, minimal weight and low profile antennas that are capable of maintaining high performance over a wide spectrum of frequencies. This technological trend has focused much effort into the design of a microstrip patch antenna. The objective of this paper is to design an microstrip line fed rectangular microstrip patch antenna which operates in C-band at 5GHz. Therefore, method of moments based IE3D software is used to design a Microstrip Patch Antenna with enhanced gain and bandwidth. IE3D is an integrated full-wave electromagnetic simulation and optimization package for the analysis and design of 3D and planar microwave circuits, MMIC, RFIC, RFID, antennas, digital circuits and high speed Printed Circuit Board (PCB). The IE3D has become the most versatile, easy to use, efficient and accurate electromagnetic simulation tool. The length of the antenna is nearly half wavelength in the dielectric it is a very critical parameter, which governs the resonant frequency of the antenna. In view of design, selection of the patch width and length are the major parameters along with the feed line dimensions. Desired patch antenna design was simulated by IE3D simulator program. The entire project is being carried out at National Atmospheric Research Laboratory (NARL), ISRO.

Metamaterials for Wireless Communications, Radiofrequency Identification, and Sensors

This paper is focused on the application of concepts derived from metamaterials to the development of novel devices, circuits, and antennas of interest in wireless communications, radiofrequency identification (RFID), and sensors. Specifically, it is shown that artificial transmission lines based (or inspired) on metamaterials exhibit interesting properties, useful for the implementation of high-performance and compact devices as well as novel functional devices. Thanks to the presence of reactive loading elements in such artificial lines, the main line parameters, that is, the characteristic impedance and the phase constant, can be engineered. This has opened new paths for RF and microwave circuit and antenna design on the basis of impedance and dispersion engineering.

New approach to a fast and accurate design of microwave circuits with complex topologies

A robust simulation-driven design methodology of microwave circuits with complex topologies has been presented. The general method elaborated is suitable for a wide class of N-port unconventional microwave circuits constructed as a deviation from classic design solutions. The key idea of the approach proposed lies in an iterative redesign of a conventional circuit by a sequential modification and optimisation of its atomic building blocks. The speed and accuracy of the method presented has been acquired by solving a number of simple optimisation problems through surrogate-based optimisation (SBO) techniques, which offer a satisfactory approximation of the optimal design solution. Two exemplary designs have been supplied to verify the method introduced. An abbreviated wideband quarter-wave impedance matching transformer and a miniaturised hybrid branch–line coupler have been developed. Diminished dimensions of the circuits under construction have been achieved by means of compact microstrip resonant cells. As an SBO engine, an implicit space mapping technique has been utilised. The final results have been acquired in only a fraction of time that is necessary for a direct electromagnetic (EM) optimisation to generate competitive results. An experimental validation of the method proving its high utility has been provided.

A High Slow-Wave Factor Microstrip Structure With Simple Design Formulas and Its Application to Microwave Circuit Design

This paper proposes a new microstrip slow-wave structure. The unit cell comprises a Schiffman section of meander line and a shunt open-circuited stub. No via-holes and ground-plane patterns are required. Simple design formulas can be used to obtain line parameters, such as the characteristic impedance and phase velocity. According to the analysis, the characteristic impedance and slow-wave factor of the proposed slow-wave line can be independently controlled by merely two layout parameters. The proposed uniplanar structure only requires a single-layer substrate and is simply constructed using the conventional printed circuit board manufacturing process. A branch-line and a rat-race coupler were designed and fabricated using the proposed structure to demonstrate its feasibility. Their sizes are only 8.49% and 4.87% of the conventional ones, respectively. This novel slow-wave structure should find wide applications in compact microwave circuits.

Large-Signal Oscillator Design Procedure Utilizing Analytical $X$-Parameters Closed-Form Expressions

New analytical behavioral model formulations based on the polyharmonic distortion (PHD) model have been successfully used to describe the nonlinear behavior of transistors and circuits. In this paper, the PHD model and its associated analytical <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">X</i> -parameters formulation will be utilized to provide an analytical design procedure for use in nonlinear microwave circuit design. For RF oscillator design, the negative-resistance method based on the analytical manipulation of scattering parameters is very popular due to its high rate of success in oscillation frequency prediction. However, it cannot be used to accurately predict the oscillator performance because it is based on linear parameters. To overcome this limitation, new analytical expressions based on large-signal <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">X</i> -parameters have been developed for use in transistor-based oscillator circuit design. The robustness of this new approach has been validated by designing and manufacturing a 5-GHz microwave oscillator.

An extraction technique for small signal intrinsic parameters of HEMTs based on artificial neural networks

This paper presents a fast and accurate procedure for extraction of small signal intrinsic parameters of AlGaAs/GaAs high electron mobility transistors (HEMTs) using artificial neural network (ANN) techniques. The extraction procedure has been done in a wide range of frequencies and biases at various temperatures. Intrinsic parameters of HEMT are acquired using its values of common-source S-parameters. Two different ANN structures have been constructed in this work to extract the parameters, multi layer perceptron (MLP) and radial basis function (RBF) neural networks. These two kinds of ANNs are compared to each other in terms of accuracy, speed and memory usage. To validate the capability of the proposed method in small signal modeling of GaAs HEMTs, data and modeled values of S-parameters of a 200μm gate width 0.25μm GaAs HEMT are compared to each other and very good agreement between them is achieved up to 30GHz. The effect of bias, temperature and frequency conditions on the extracted parameters of HEMT has been investigated, and the obtained results match the theoretical expectations. The proposed model can be inserted to computer-aided design (CAD) tools in order to have an accurate and fast design, simulation and optimization of microwave circuits including GaAs HEMTs.

Computational Optimization Algorithms for Antennas and RF/Microwave Circuit Designs: An Overview

This paper provides an overview of optimization algorithms for antennas and radio frequency (RF)/microwave circuit designs. The significance of wireless communication to our daily lives and industrial engineering will first be discussed. Antennas and circuits used in wireless communication will then be introduced followed by a discussion on the need for optimization. After that, this paper will focus on three widely used optimization algorithms for antennas and RF/microwave circuit design. A survey of the optimization of antennas and microwave devices available in the literature will be presented and will include the use of other optimization algorithms. For illustration purposes two optimization examples with measurement results will be given.

Electrically Small Resonators for Planar Metamaterial, Microwave Circuit and Antenna Design: A Comparative Analysis

Planar metamaterials and many microwave circuits and antennas are designed by means of resonators with dimensions much smaller than the wavelength at their resonance frequency. There are many types of such electrically small resonators, and the main purpose of this paper is to compare them as building blocks for the implementation of microwave components. Aspects such as resonator size, bandwidth, their circuit models when they are coupled to transmission lines (as is usually required), as well as key applications, will be considered.

Split rings for metamaterial and microwave circuit design: A review of recent developments (Invited paper)

This article is a review of recent applications of split rings to the design of planar microwave circuits based on metamaterial concepts. The considered resonators, namely, split-ring resonators (SRRs), complementary SRRs (CSRRs), and their open counterparts (OSRRs and OCSRRs), are reviewed, and the equivalent circuit models of artificial lines based on such resonators, including parasitics, are presented and discussed. The second part of the article is devoted to highlight some recent applications of the considered resonators. This will include the design of dual-band components and wideband bandpass filters based on the combination of OSRRs and OCSRRs, the design of tunable components based on cantilever-type SRRs, and the design of CSRR-based differential (balanced) lines with common-mode suppression. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE 22:439–458, 2012.

Very low frequency tunable signal generator for neural and cardiac cell stimulation

An integrated circuit capable of generating very low-frequency signals for biomedical applications is presented in this article. By employing microwave circuit design concepts and techniques, the chip can produce very low frequency signals starting from a pair of 4 GHz signal generators. Measurements reveal that a continuous set of frequencies between 0.03 Hz and 185 Hz are generated, which represents a tuning range of 6167:1. The chip was fabricated using a standard 0.13-µm CMOS process and the circuit core measures 0.49 mm2.

An empirical I‐V nonlinear model suitable for GaN FET class F PA design

AbstractThis article presents an improved nonlinear IDS(VGS, VDS) model useful for modeling the experimental pulsed I‐V measurement data of GaN FETs operated at large drain‐source voltages. This improved IDS(VGS, VDS) model is based on the Chalmers model. The main features of the improved nonlinear IDS(VGS, VDS) model are the two analytical expressions that are incorporated to model the output conductance and the saturation voltage. The new model only requires 13 parameters easily determined from experimental pulsed I‐V data. Comparison between simulated and measured data of an inverse class F PA designed with a commercial GaN FET at 1.5 GHz demonstrate that the proposed model is suitable for microwave circuit design based on GaN transistors. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:1256–1259, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25980

Drifting-Dipole Noise (DDN) Model of MOSFETs for Microwave Circuit Design

Physic-based formulations for the high-frequency noise characteristics of nanometer MOSFETs working at saturation are developed. In the derivation, field-dependent mobility, as well as carrier heating effect in the gradual channel approximation region, is taken into account. In addition, diffusion noise due to velocity saturation carriers in the high electric field region is calculated using Statz's drifting dipole theory. Excellent agreement between the proposed model and experimental noise data for 120-nm MOSFET technology was obtained over device sizes, biases, and frequencies up to 26 GHz. The analytical noise model can be incorporated into any compact model to enable first-pass silicon design of microwave circuit.

Development and design of multilayer antennas based on liquid crystals

In this paper we present a conception and design of microwave circuit based on liquid crystal. The conception will be made of a manner to have a device that functions with a dual frequency and dual polarization. The goal of the dual frequency and dual polarization is to provide a multi-dimensional picture of meteorological phenomena to get more complete data of survey climatic long term and also for the use precipitation of the pictures in the radars. The whole system required in the broadcasts of space as in satellite imaging systems.The liquid crystal polymer has unique features: electric, mechanical, chemical; its extremely flexible nature and the capacity to be laminated with a low cost and a lightweight, to return an appropriate substrate for the big applications of the multilayer antennas.

Modeling of mutual coupling of arbitrary order in coupled circuits and array antennas

This article presents a fundamental strategy for accurately modeling the mutual coupling of arbitrary order in any large-scale electromagnetic structures and high-density integrated chips such as antenna array elements and coupled circuit elements. The proposed method starts from the modeling of the first-order mutual coupling, and it consists of two main steps. First of all, an equivalent circuit model describing low-order mutual coupling (adjacent coupling) is characterized and established, of which each parametric value is accurately extracted by making use of a numerical calibration technique. Then, the circuit model for high-order mutual coupling (crossover or crosstalk coupling) is generated from the lower order models, and it can further be used for the modeling of mutual coupling of any higher order. The accuracy and efficiency of the proposed method are demonstrated by three different kinds of structure including a linear phased array antenna, a finite periodic electromagnetic structure, and a planar low-pass filter. This novel approach represents an easy, fast, and effective characterization of arbitrary-order mutual coupling. It can find applications in the modeling of mutual coupling between any circuit elements and building blocks such as antennas, resonators, and even small discontinuities, and it promises to be helpful for the analysis and iterative design of microwave circuits and antenna arrays. © 2010 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2011. © 2011 Wiley Periodicals, Inc.

Analysis of the gate current as a suitable indicator for FET degradation under nonlinear dynamic regime

Electron device degradation, although not directly accounted for, represents a key issue in microwave circuit design. This is especially true when the particular applications involved (e.g., satellite, military, consumer) do not allow or strongly discourage any kind of maintenance. As a matter of fact, in order to account for device degradation in circuit design, a suitable electron device model is needed which is able to predict the performance degradation as a function of the actual electrical regime involved in the device operation. Such a kind of model is not available in literature. In this paper, quantitative results are provided for device degradation indicators which correlate DC and RF stress experiments. These results can be considered an important step toward the definition of a nonlinear model accounting for device degradation.

PSO를 이용한 주파수 선택 구조 기반 인공 자기 도체 설계

본 논문에서는 주파수 선택 구조를 기반으로 하는 인공 자기 도체 구조를 설계하기 위하여 최적화 알고리즘 중 하나인 particle swarm optimization(PSO) 기법을 이용하였다. 주파수 선택 구조로서 Jerusalem Cross를 갖는 인공 자기 도체의 등가 회로 모델에 PSO를 적용하여, 원하는 공진 주파수 대역을 갖는 최적의 설계값을 얻어낼 수 있음을 확인하였다. 우선 유도한 등가 회로 모델로부터 공진 주파수와 반사 계수 위상 특성을 구하여 상용 소프트웨어로 얻은 값과 일치하는 것을 확인하여 본 논문의 유효함을 확인하였으며, 이로부터 원하는 공진 주파수에 대해 최적화 과정을 통하여 설계 파라미터를 추출하였다. 본 논문에서 유도한 최적화 과정을 이용한 주파수 선택 구조 기반 인공 자기 도체 구조 설계 방법을 이용하여 여러 다른 종류의 주파수 선택 구조 형태를 갖는 인공 자기 도체 구조뿐만 아니라, 인공 자기 도체 구조를 이용한 소형 안테나 접지면 설계 등 마이크로파 회로 설계에 유용하게 사용할 수 있다. In this paper, particle swarm optimization(PSO) is applied for the design of frequency selective surface based artificial magnetic conductor. An equivalent circuit model for this artificial magnetic conductor(AMC) with Jerusalem Cross arrays was derived and then PSO was applied for obtaining the optimized geometrical parameters with desired resonant frequency. The resonant frequency and the reflection phase characteristics from the optimization were compared to the results from commercial software for verifying the validity of this paper. The procedure presented in this paper can be applied to design the AMC with different frequency selective surface and also can be used for the design of microwave circuits like the AMC ground planes.

On the effects of resonator's electrical size on bandwidth in resonant-type metamaterial transmission lines

In this article, an analysis of resonant type metamaterial transmission lines is carried out.Specifically, the effects of the dimensions and resonator characteristics on the frequency response are studied and interpreted to the light of the equivalent circuit model of the lines based on split ring resonators and complementary split ring resonators. In this work, the duality between both kinds of lines can also be observed. This study is important for the application of these artificial lines to microwave circuit design, because important guidelines concerning device bandwidth can be inferred. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1526–1530, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25232

Unconditional Stability Boundaries of a Three-Port Network

An analytical approach for acquiring the explicit expressions of the boundaries concerning the unconditional stability regions of a three-port network is presented. This approach begins with the expressions for the input reflection coefficients S 11 ' and S 22 ' at ports 1 and 2 of a three-port network having port 3 terminated with ?3 . |S 11 '| = 1 and |S 22 '| = 1 then give two stability circles in the ?3-plane. One can graphically determine that the tangent point of these two stability circles is on the boundary of the unconditional stability region for the terminating port. The explicit expressions of the boundary for port 3 are then acquired. This procedure may be followed for the other two ports in order to fully characterize the unconditional stability boundaries of a three-port network. In addition, issues pertaining to uniqueness and continuity in the plotting of unconditional stability boundaries are addressed. Using the agilent advanced design system software tool, the derived expressions of the unconditional stability boundary for the terminating port and related extreme phase values of reflection coefficients of the other two ports are implemented. These derived expressions can then enhance the computer-aided capability on the stability analysis of a three-port network and provide useful information for the microwave circuit designer.

Oversized microstrip line as differential guided-wave structure

An oversized microstrip line as a differential guided-wave structure is proposed. For most guided-wave structures such as microstrip line and waveguide, the signal transmission will be in the form of fundamental mode propagation, where higher-order mode propagations should be avoided. In this reported work, the first higher-order propagation mode (TE10) of a microstrip line is excited. Its guide-wave characteristic was simulated and measured. The oversized microstrip line supporting TE10 propagation mode is proposed for the microwave and millimetre-wave differential circuit and system designs.

Invited Paper: Applications of vector non-linear microwave measurements

This study discusses the present day capabilities of vector non-linear microwave measurements. It starts off with a historical review on the development of such instrumentation. Next, the author elaborates on how vector non-linear measurements changed the way in which models for non-linear microwave devices are validated and constructed, how they broadened physical understanding, and how they have impacted microwave circuit design.