On the EMC dipole feed-line parasitic radiation

A rigorous analysis of the electromagnetically coupled microstrip dipole based on potential integral equations, Green's functions, and the moment method is presented. The computations of the antenna's radiated field using the steepest descent technique is then detailed, and the theoretical results are compared with experimental measurements in the X-band. By considering the feed as an antenna part, the excitation line parasitic radiation is shown clearly. Two possibilities to reduce this parasitic phenomenon are proposed. Also, it is shown that in any microstrip structure (one or two layers) excited by a microstripline, the feed parasitic radiation is nonnegligible     

Transient radiation from a linear antenna with nonreflecting resistive loading

The transient waveforms radiated by step voltage or Gaussian pulse excited resistively loaded linear antennas are investigated by numerical means. Current distributions on the harmonically excited antenna are obtained as functions of frequency and for different values of the loading. The transfer functions of the antenna and the spectral densities of the radiated waveforms are obtained as functions of frequency and the loading and for different directions in space. The time dependent radiated waveforms produced by the antenna are obtained by using the fast Fourier inversion technique. The effects of the various antenna parameters on the radiated waveforms are also investigated. Some of the results are compared with available approximate analytical results.     

A novel systematic approach for equivalent model extraction of embedded high-speed interconnects in time domain

Based on time-domain scattered data, an efficient systematic approach in the time domain has been proposed to extract the SPICE-compatible models of embedded high-speed interconnects. The approach combines the layer-peeling technique and the generalized pencil-of-matrix method to obtain a pole-residue representation of the step response of the interconnects. An order-reduction procedure is implemented based on the bandwidth criterion to find the optimum pole-residue representation of the interconnects with minimum pole numbers. The SPICE-compatible lumped circuits are then systematically extracted from the pole-residue rational functions. The discontinuous microstrip lines and bonding wire structure are used to demonstrate the validity of the proposed approach. Good agreement is seen between the modeled and measured transient response. The advantages of this approach are the de-embedding ability for arbitrary nonuniform interconnects, systematically obtaining lower order and more accurate SPICE-compatible circuits, and broad-band performance of the extracted circuits.     

Transient analysis of radiated field from electric dipoles andmicrostrip lines

The transient response of the field radiated from electric dipole sources and microstrip lines with arbitrary time waveforms is analyzed. By using the three-dimensional Fourier transform of the spectral dyadic Green's function, relative to the integrated structure, an analytical closed-form solution is obtained and equivalent circuits for the analysis of the transient phenomena in the far-field region are derived. Numerical examples are provided to obtain noticeable insights to the behavior of planar circuits working under Gaussian pulsed excitation     

Calculation of Transient Radiation Parameters of Aperture

Transient radiated field from aperture antennas is derived by using the field equivalence principle. For Gaussian pulse excited uniform and tapered planar apertures, transient radiation parameters, such as radiation energy pattern, the half-energy beamwidth and directivity, are calculated. The simulation formulations for calculating the half-energy beamwidth and directivity are presented     

A frequency-domain approach to interconnect crosstalk simulation and minimization

A frequency-domain approach to efficiently simulate and minimize the crosstalk between high speed interconnects is proposed in this paper. Several methods for modeling coupled microstrip transmission lines are discussed. Several possible simulation strategies are also considered. A straightforward yet rigorous frequency-domain approach is followed. This approach can be used for linearly and non-linearly terminated microstrip coupled lines, since it exploits the harmonic balance technique. A typical example of microstrip interconnects is simulated and the results are compared with those obtained in previous work by other authors using time-domain methods. The simulation method proposed in this work yields good accuracy. A crosstalk minimization problem is formulated and solved following the method proposed.     

The Radiation of Electromagnetic Power by Microstrip Configurations

A new technique for calculating the radiation losses of microstrip configurations is presented. The method applies if the wavelength is large compared to the width of the conducting strip and the thickness of the dielectric wafer. It is shown that the radiated power, which is partly carried by "space waves" and partly by "surface waves," can be computed in terms of the specific inductance and the specific capacitance of the transmission line, without making any assumptions regarding the current distribution in the microstrip. It appears that the fraction of the radiated power carried by surface waves contains the frequency to a higher power than does the fraction carried by space waves and is therefore relatively small. The investigated configurations are the infinitely long transmission line excited by a voltage-slit, the half-wavelength straight resonator, the full-wavelength circular resonator, and the quarter-wavelength hair-pin resonator. It follows that the quality factor of the straight resonator and the circular resonator are inversely proportional to the square of the frequency, whereas the quality factor of the hairpin resonator is inversely proportional to the fourth power of the frequency.     

Radiated emissions and immunity of microstrip transmission lines:theory and reverberation chamber measurements

The increasing complexity of electronic systems has introduced an increased potential for electromagnetic interference (EMI) between electronic systems. We analyze the radiation from a microstrip transmission line and calculate the total radiated power by numerical integration. Reverberation chamber methods for measuring radiated emissions and immunity are reviewed and applied to three microstrip configurations. Measurements from 200 to 2000 MHz are compared with theory, and excellent agreement is obtained for two configurations that minimize feed cable and finite ground plane effects. Emissions measurements are found to be more accurate than immunity measurements because the impedance mismatch of the receiving antenna cancels when the ratio of the microstrip and reference radiated power measurements is taken. The use of two different receiving antenna locations for emissions measurements illustrates good field uniformity within the chamber     

Estimation of spurious radiation from microstrip etches usingclosed-form Green's functions

The problem of spurious radiation from electronic packages is considered by investigating the power radiated from microstrip etches that are excited by arbitrarily located current sources and terminated by complex loads at both ends. The first step in the procedure is to compute the current distribution on the microstrip line by using the method of moments (MoM). Two contributions of this paper are: (i) employing the recently derived closed-form Green's functions in the spatial domain, which permits an efficient computation of the elements of the MoM matrix; and (ii) incorporating complex load terminations in a convenient manner with virtually no increase in the computation time. The computed current distribution is used to calculate the spurious radiated power, and the result is compared with that derived by using an approximate, transmission line analysis     

Transient response of the infinite cylindrical antenna and scatterer

The transient response of an infinite cylindrical antenna and scatterer is obtained by time gating a time-dependent electric-field integral equation for thin wires of finite-length. The driving point current and broadside radiated field approximate the driving point voltage in the antenna case, while the current excited in the scattering case approximates the time integral of the incident field. This approximate integral relation is used to estimate currents excited on cylindrical structures without employing the complete integral equation solution procedure.     

A theoretical study of the input impedance of a circular microstrip disk antenna

A theoretical study is presented of the input impedance of a circular microstrip disk antenna excited by a coaxial line. The theory is based on Green's function technique applied to the disk cavity with the boundary admittance at the edge. Both the feed pin size and the boundary admittance are shown to be important in deriving the analytical expression for the input impedance. The boundary admittance is obtained by considering the radiated power and the electric and magnetic stored energies in the fringe capacitance. The analytical expression for the input impedance includes the feed location, the feed pin size, the disk size and thickness, and the dielectric constant of the material, and is useful for optimizing various parameters. The calculations are compared with experimental data showing a good agreement.     

锥削分布圆形口径场的瞬态辐射

利用电磁脉冲的口径瞬态辐射场计算公式,针对锥削分布圆形口径的同相口径场及线性相移、平方律相移等非同相口径场情况,计算了辐射高斯脉冲时的E面能量方向图、半能量波瓣宽度及面积利用系数等参数。计算表明,对于锥削分布圆形口径场,其辐射场特性与口径面半径、激励脉冲宽度及口径面锥削分布指数有着密切的关系。     

The phase center position of a microstrip horn radiating in aninfinite parallel-plate waveguide

In this paper the field radiated by a flared microstrip line in an infinite parallel-plate waveguide with separation between plates of less than half a wavelength is studied. The field at any point of the parallel-plate waveguide is expressed as a summation of modal solutions of the Helmholtz equation. The phase center of the microstrip horn is calculated for uniform amplitude distributions along the horn aperture. The theory may be applied to obtain the phase and amplitude distributions along the output ports of microstrip bootlace lenses     

Analysis of a wide radiating slot in the ground plane of amicrostrip line

An analysis of a wide rectangular radiating slot excited by a microstrip line is described. Coupled integral equations are formulated to find the electric current distribution on the feed line and the electric field in the aperture. The solution is based on the method of moments and using the space domain Sommerfeld-type Green's function. The information about the input impedance or reflection coefficient is extracted from the electric current distribution on the microstrip line utilizing the matrix pencil technique. The theoretical analysis is described and data are presented and compared with other theoretical and experimental results     

Spurious radiation from a practical source on a covered microstripline

The TM₀ parallel-plate mode field that is radiated from the currents induced on a covered microstrip transmission line by a finite-gap voltage source is studied. The behavior of the total radiation field (the field radiated by the total strip current) is investigated, along with the field radiated by the constituent current components that make up the total current, namely the bound-mode (BM) and continuous-spectrum currents. The continuous-spectrum current is further resolved into the sum of a physical leaky-mode current and a residual-wave current, and the fields radiated by each of these separate components are examined. It is determined that leaky-mode fields can contribute to crosstalk and other interference effects near the source and within an angular leakage region, while the radiation field from the BM current is the predominant mechanism for these effects further away from the gap source, outside the leakage region. The field radiated from the residual-wave current can be quite strong in the "spectral-gap region," which is the frequency region where the leaky mode is nonphysical, and therefore the leaky mode does not contribute directly to the spectrum of current on the strip in the decomposition used here     

非同相口径场瞬态辐射的计算

利用电磁脉冲的口径瞬态辐射场计算公式,针对圆形口径的线性相移、平方律相移等非同相口径场情况,计算了辐射高斯脉冲时的能量方向图、半能量波瓣宽度、面积利用系数等参数.计算表明,对于圆形口径非同相口径场,最大辐射场的方向为口径面法线方向,同时能量方向图关于口径面法线方向对称;随着口径的增大,波瓣变窄,无副瓣;随着平方律相移的滞后参数的增加,波瓣变宽,主瓣不分裂.     

Simulation of high-frequency integrated circuits incorporatingfull-wave analysis of microstrip discontinuities

Incorporates full-wave simulation of microstrip interconnects into circuit analysis and shows how predicted responses diverge from those based on models from a modern microwave-circuit CAD package. A method is presented for characterizing microstrip interconnects and discontinuities through the method of moments applied to a mixed-potential integral equation. The speed is greatly improved through the use of a recently published techniques for rapid evaluation of microstrip spatial Green's functions. A microstrip circuit element is analyzed separately with this procedure, and scattering parameters are extracted from the computed current density. These parameters are passed to a circuit simulator, where small- and large-signal analyses reveal how differences in interconnect modeling affect predicted responses     

Calculation of the field radiated by horn-antennas using themode-matching method

Methods employed for evaluating fields radiated by horn antennas, like the aperture field method and the spherical wave expansion, have not taken into account the contribution by fields existing outside the horn aperture (e.g., along the outer walls of the horn). The use of the mode-matching technique for analyzing the transition from horn antenna to free space makes it possible to include in the analysis even those fields which exist outside (e.g., behind) the horn aperture when determining the far as well as the near field. Furthermore, the effects of the finite wall thickness and the discontinuity caused by the transition from waveguide to free space are also taken into account. A suitable development of the fields at the transition of the conical/corrugated horn to free space using the mode-matching technique is presented. Two different convergence diagrams, depending on the kind of modes excited in the horn antenna, are given. They show the results from extensive convergence investigations. With the help of these diagrams, a reliable evaluation of the fields radiated by horn antennas is guaranteed. Practical measurements of the fields radiated by horn antennas confirm the field distributions gained through analysis     

Theoretical and experimental characterization of transientelectromagnetic fields radiated by electrostatic discharge (ESD)currents

The problem of the evaluation of the electromagnetic (EM) field radiated by an electrostatic discharge (ESD) current is examined, and an efficient numerical code for the evaluation of the radiated field is developed. The considered radiating structures, a monopole and a loop, are analyzed in the time domain using a modified electric field integral equation (EFIE). A modification of the integral equation was introduced in order to take into account the reflection of the incident pulse at the input terminals of the antenna, when fed by a transmission line. The reflected wave is very significant and its evaluation is fundamental for the comparison of theoretical and experimental data. The ESD current flowing along the wire is determined using the method of moments in time domain (MoMTD). From the knowledge of the transient current, the radiated EM field is evaluated by a standard technique. The developed model is the first stage of a project for the characterization of the measurement environment during an ESD test. All numerical results are validated by measurements and good agreement is shown     

Electric-field distribution near rectangular microstrip radiatorsfor hyperthermia heating: theory versus experiment in water

A rectangular microstrip antenna radiator is investigated for its near-zone radiation characteristics in water. Calculations of a cavity model theory are compared with the electric-field measurements of a miniature nonperturbing diode-dipole E-field probe whose 3 mm tip was positioned by an automatic three-axis scanning system. These comparisons have implications for the use of microstrip antennas in a multielement microwave hyperthermia applicator. Half-wavelength rectangular microstrip patches were designed to radiate in water at 915 MHz. Both low (epsilon r = 10) and high (epsilon r = 85) dielectric constant substrates were tested. Normal and tangential components of the near-zone radiated electric field were discriminated by appropriate orientation of the E-field probe. Low normal to transverse electric-field ratios at 3.0 cm depth indicate that the radiators may be useful for hyperthermia heating with an intervening water bolus. Electric-field pattern addition from a three-element linear array of these elements in water indicates that phase and amplitude adjustment can achieve some limited control over the distribution of radiated power.