Analysis of microwave circuits including lumped elements based on the iterative method

A precise technique based on the wave concept iterative procedure (WCIP) and a fast mode transformation (FMT) is used to analyze a rectenna circuit. This global analysis is achieved by using surface impedance to model the non linear element (Schottky diode). These systems use the manufacturing processes of integrated circuits. In order to initialize the iterative procedure, an incident wave is defined in spectral domain. The numerical results are compared to those obtained with the measured one. The good agreement between simulated and published data justifies the design procedure.

A new fullwave global analysis of complex inhomogeneous microwave structures including passive or active, linear or nonlinear lumped elements is presented. For a given structure, only one electromagnetic simulation of the distributed part, by a three-dimensional (3-D) finite element method using edge elements, is needed corresponding to the insertion of variable lumped elements placed at the same position. Simulation results of various test cases, containing either resistor, diode, or active component, are compared with those provided by a commercial circuit analysis software or with measurements results. Our validated electromagnetic simulator is then used for analyzing a planar balanced mixer operating in the millimetric range.

Planar microwave circuits are simulated by a mixed space-spectral domain integral method which allows the consideration of space-varying impedances. For an efficient computation of scattering parameters of circuits containing lumped elements within this fullwave analysis, a bilinear transformation is used. Furthermore, by this so-called Mobius transformation it is possible to decide whether an impedance region of finite size can be interpreted as a lumped element or not. Applications to microstrip circuits are discussed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The accuracy of iterative and non-iterative strain-gage balance load calculation methods was compared using data from the calibration of a force balance. Two iterative and one non-iterative method were investigated. In addition, transformations were applied to balance loads in order to process the calibration data in both direct read and force balance format. NASA's regression model optimization tool BALFIT was used to generate optimized regression models of the calibration data for each of the three load calculation methods. This approach made sure that the selected regression models met strict statistical quality requirements. The comparison of the standard deviation of the load residuals showed that the first iterative method may be applied to data in both the direct read and force balance format. The second iterative method, on the other hand, implicitly assumes that the primary gage sensitivities of all balance gages exist. Therefore, the second iterative method only works if the given balance data is processed in force balance format. The calibration data set was also processed using the non-iterative method. Standard deviations of the load residuals for the three load calculation methods were compared. Overall, the standard deviations show very good agreement. The load prediction accuracies of the three methods appear to be compatible as long as regression models used to analyze the calibration data meet strict statistical quality requirements. Recent improvements of the regression model optimization tool BALFIT are also discussed in the paper.

A computer program is described that performs a Volterra-series analysis of a weakly nonlinear microwave circuit having an arbitrary topology. The program uses the method of nonlinear currents and a nodal formulation. In this approach, each nonlinear circuit element is described as a linear element in parallel with a set of current sources; each current source represents a single order (greater than one) of the mixing products, and its current is a nonlinear function of the node-voltage components at lower-order mixing frequencies. The weakly nonlinear circuit is reduced to a linear circuit, which contains the linear elements and the linear parts of the nonlinear elements, and a set of excitation sources. The program is intended primarily for use in the design of microwave circuits; its catalog of circuit elements includes the distributed elements necessary for such work. Because the program formulates and solves the circuit equations numerically, the user need not simplify either the circuit or the model of the solid-state device, or make any of the other common simplifying assumptions. >

This paper introduces a new formulation of the iterative wave method to study the DGS `Defected Ground Structure' technique applied to the SIW `Substrate Integrated Waveguide' technology. This makes possible the analysis of arbitrary forms of the ground and circuit planes and the{non-conventional} metallic via holes configuration. The study is based on the recursive relationship of longitudinal reflected and incident waves in both spatial and spectral domains. The unconditional stability and the convergence of the method were well verified. In fact, we will validate the proposed approach by the analysis of a SIW filter with folded DGS. The numerical results are in good agreement with those obtained by the HFSS software `High-Frequency Structure Simulator'. Moreover, the presented method shows a considerable reduction in the required computational resources, which proves the high effectiveness of our method.

The circuit modeling and analysis of resonant inverters is complex because the state variables such as inductor currents and capacitor voltages are AC dominant. The phasor dynamic modeling method maps the periodical time-varying state variables into stationary frame for each harmonic of interest. Correspondingly, the circuit is decomposed into two DC subcircuits, the state variables of which are the time-varying Fourier coefficients of the original AC variables. A small-signal model can be derived by applying small perturbation and linearization to the Fourier coefficients. A phasor-domain modeling method is used to investigate the resonant inverters in high-frequency AC power distribution systems. A resonant inverter system with five energy storage elements is modeled and simulated, and compared with switch simulation for both steady state and transients. The phasor model simulation matches the switch model simulation in both steady state and transients, but takes much less computing time. In addition, this model closely relates to the power converter topology in time domain, and therefore, keeps the physical meaning of the state variables. It can be used for high accuracy of modeling, simulation, and circuit analysis and control design. It can be extended to a higher order of resonant topologies including parasitic components. A high-frequency AC system with two pulse-phase-modulation-controlled resonant inverters is modeled and simulated, and the current distribution control is investigated with the phasor model. The model simulation is compared with switch-level simulation and experimental results.

This paper describes microwave circuit analysis programs techniques for general purpose which perform frequency domain analyses. Differing techniques used in two programs are described. The first uses transfer matrix analysis and is limited to networks having tree structured topologies and two-port devices such as transmission lines, stubs and lumped elements. It runs on a time-shared computer and is used for interactive design. The second program can analyze any linear network including those with multiport elements such as coupled transmission lines. This uses a nodal representation for the circuit and relies on inverting an admittance matrix to perform the analysis. In the first program the user describes his circuit in terms of topology as well as circuit elements. By this technique, a considerable reduction in computer size needed to run this program is effected. A 60 element circuit can be run on a commercial time-sharing service with less than 6K words of available core. The second program requires a large computer; for example, 32K words or core storage are required to analyze a 50 node circuit.

In this paper, analysis of fractional order passive RC low-pass filter circuit is presented. The time domain behaviors were expressed for different values of fractional order α. The output of fractional order low-pass filter for order α has been simulated by MATLAB software. The effect of fractional order α on frequency response is represented as simulation results. The design of these filters using an approximation of the fractional Laplacian operator is outlined. A fractance device of order α which uses usual expression sα is analyzed and presented using continuous fraction expansion (CFE) method. The fractional order operator α is rationalized approximately by using different methods (Oustaloup, Newton and CFE method) and is presented and compared with the ideal response of the filter circuit. The fractional order circuits have better design flexibility than the integer-order circuits. The performance of integer-order circuit is improved by the replacement of fractional component as it has greater degree of freedom.

In this paper, the authors propose a BSF design of quasi-lumped elements realizing on the SSL structure. The building lumped elements, inductors and capacitors, are composed of various patterns of planar metallic patches which might reside on either or both sides of the SSL's central stripline. A lumped elements circuit model is developed to analyze the prototype filter's frequency response. The proposed BSF is built from alternatively cascading series circuit blocks and shunt circuit ones with each of the circuit blocks composing of an inductor and a capacitor. The lumped elements are in shunt-connection in the series modules and the filter's shunt blocks have the elements in a series-connection form. Each of the circuit blocks can individually provide a transmission zero to the filter's frequency response. A wideband BSF can be realized while multiple zero are properly arranged. The filter stopband BW is controlled by the combinations of the created transmission zeros. A wideband BSF can be realized while the multiple zeros are properly arranged. Experiments are conducted to verify the filter's performance and good agreements are observed between the circuit model simulation and the measurements.

Strategies for solving the air flow—Thermal problem in multiroom buildings

Two methods for extraction of the effective tensor surface impedance representing metasurfaces with printed elements and arbitrary geometry are presented. The surface impedance can be modelled as a shunt admittance on a transmission line. The extracted surface impedance combined with transmission line theory enables to compute easily and efficiently the transmission coefficient through a multilayer metasurface structure. The metasurface modelling as a shunt admittance enables to conduct a multi‐parameter study on the transmission and reflection performance through the metasurface structure. The results of the proposed methods are compared, and very good agreement was obtained up to 30° incident angle. Beyond 30° it is suggested to recalibrate the model or upgrade it. For model validation purposes, a 2D flat lens antenna with patch elements loaded with capacitors was designed, fabricated, and measured. Simulation and experimental results of the lens near and far‐field are presented.

Leaky wave antennas can be designed in many ways. One design parameter is the surface impedance which can be controlled by varying the transmission line in order to leak energy and radiate by creating varying gaps in the line. Controlling the surface impedance can also be achieved by changes in the dielectric substrate of the antenna. The work presented in this paper demonstrates a new way to change the surface impedance by embedding conductive micron-sized particles in the substrate. More specifically, the conductive micron-sized particles can be moved using external magneto-static fields, thus changing the overall effective permittivity of the substrate. Simulation results at 10 GHz show that a change in surface impedance can be achieved by manipulating the microparticles in the substrate, rather than changing the gaps in the transmission line. Finally, the simulation results are validated with a comparison to published literature.

This letter introduces an energy sensitive bandpass filter (ESBPF) to protect Ku-band low noise amplifiers (LNAs) from high power electromagnetic (HPEM) threats. The ESBPF circuit has anti-parallel Schottky Barrier diodes mounted on a planar bandpass filter (BPF) circuit. The ESBPF operates as a BPF at a power level below the maximum permissible power level (MPPL) of the LNAs. However, the circuit works like a variable attenuator at the power level equal to or higher than the MPPL of the LNAs. To increase attenuation and selectivity functions, a 63 $^{\circ}$ line section between two planar filter circuits loaded transversely along WR-75 waveguide has been inserted to cascade. The development of the circuit model has been started with lumped elements under the condition of a 0 dBm MPPL of LNA. Then, the model has been simulated, optimized with HFSS, and fabricated. Measurement results show that the ESBPF has insertion loss less than 1.27 dB at the power level lower than $-$ 2 dBm for the frequency range from 11.8 to 12.3 GHz. At the power level higher than $-$ 2 dBm, the circuit provides different levels of attenuation depending on the input power within the identical frequency band; 31 dB insertion loss, which provides isolation characteristic, has been measured at the power level of 30 dBm.

A unique design technique of power line filter is being proposed. It is based on the conventional technique of composite low pass filter. The equivalent circuit of the composite low pass filter is being presented in the two different modes by considering the modal propagation of noise. The consideration of composite LPF is taken into account in the design technique of power line filter. In order to accurately predict the insertion loss of the filter the effects of non-ideal behaviour of the passive lumped components are considered. It is based on the parasitic effect of the passive lumped elements. The filter is then characterized using S-parameters. The response of the filter's circuits is simulated using advanced design software (ADS). Keywords: Conducted emission, Composite filter, electromagnetic compatibility, lumped elements, and power line filter. I. Introduction Switching and modulation techniques are used for efficient use of electrical power. Widely used Switched mode power supplies (SMPS) for powering today's electronics loads is a most common example. Unfortunately, all the power control techniques deliberately distort sinusoidal wave form of power frequency and generate unwanted interfering signals. Obviously, they all are often cited as one of the main source of conducted emission (CE). Usually the power supplies which are using controlling techniques cannot comply with the strict electromagnetic compatibility (EMC) regulations. In order to meet the limit set for conducted EMI, power supplies require a filter at its input. Conducted EMI generated through particular equipment gets coupled into other equipments mostly through power line cables. CE can be controlled by using filters and increasing line impedance. Conducted EMI has two components: The common mode (CM) interference and differential mode (DM) interference. The coupling mechanisms of these interferences are different (4). The difference in the direction of propagation of these coupling currents along the phase and neutral line, leads to differential mode ( ) current and common mode ( ) current. Therefore design of EMI filters demand decoupling of these two modes (2). This paper attempts to describe a design technique for Power Line filter using classical design technique. 1.1 Characterization of common mode & differential mode currents