Cavity Model Analysis Research Articles

Cavity Model Analysis of Gauging Trowel Shaped Patch Antenna with Circular Metal Rings

Cavity Model Analysis of Gauging Trowel Shaped Patch Antenna with Circular Metal Rings

Simplified calculation method for hydrodynamic noise of multi-tube heat exchanger based on acoustic cavity model

Because of the complex structure of the heat exchanger, its hydrodynamic noise simulation is difficult and the problem of low computational efficiency can not be solved well. An acoustically simplified calculation method for a large shell and tube heat exchanger with 2000 heat transfer tubes is proposed for a multi-tube number heat exchanger. The heat exchanger tubes are equated to different numbers of heat exchanger tubes according to their through-flow areas of 2000 heat exchanger tubes. Based on the LMS Virtual.Lab acoustic finite element module, acoustic cavity model calculations and analysis are performed for heat exchangers with different numbers of heat transfer tubes. From the acoustic cavity model laws of heat exchangers with 20, 100, 500 and 1000 tubes, it can be found that the distribution of vibration patterns and the intrinsic frequencies of heat exchangers with different tube numbers are similar. Therefore, the calculation model of 20 heat exchanger tubes is selected for noise calculation based on the fluid calculation software ANSYS-CFX and the acoustic calculation software ACTRAN. Based on the results of the noise calculation and the comparison verification of the experimental data, it is concluded that the heat exchanger models with similar acoustic cavity model have similar sound pressure levels. In addition, the sound transmission loss law and the contribution of the acoustic cavity model of the shell and tube heat exchanger are analyzed. Therefore, the effectiveness of the simplified calculation method of multi-tube number heat exchanger proposed is verified. The proposed simplified calculation method can be used to reduce the calculation difficulty and improve the calculation efficiency of complex heat exchangers.

An incremental indentation energy method in predicting uniaxial tensile properties of ferritic-austenitic dissimilar metal welds from spherical indentation tests

Based on the expanding cavity model and energy analysis, an analytical derivation was first conducted to develop a correlation between the increment of elastic and plastic portions of external work and the von Mises stress-strain increment, yielding an incremental indentation energy method (IIEM) to determine the stress-strain relationship from spherical indentation tests (SITs). The IIEM has two potential approaches in determining the proportional limit, one from indentation plastic zone radius rp measurements and the other from trial-and-error. Through an application of digital image correlation on the various zones of ferritic (SA508Gr.3Cl.1) to austenitic stainless steel (316L) dissimilar metal welds (DMWs), it was found that the rp measurements is capable for the two bases, but failed in the other six zones due to the inhomogeneous characteristic of DMWs. In this case, the mean strain development of indentation plastic zone was extensively investigated through systematic finite element analysis to establish an IIEM independent of rp measurements. Solidarity of the IIEM was verified through experiments on the eight representative zones of DMWs, and compared with its previous counterpart (the empirically concluded Kwon method). It was found that the IIEM can restrain errors caused by the compensation effect in reverse predictions, leading to more accurate strength predictions (with a maximum error 9.85%). This study is expected to provide a convenient and reliable approach for predicting the uniaxial tensile properties from SITs, especially when the rp measurement is not applicable.

Cavity model analysis of dual polarized microstrip antennas for wireless body area network application

Cavity model analysis of dual polarized microstrip antennas for wireless body area network application

Conical annular patch antenna for dual band operation on airborne vehicles

An annular patch antenna operating in both TM04 and TM05 modes and conformed to a conical surface is proposed for airborne applications. Dual-slot loading is done to obtain a high gain linearly polarized broadside radiation pattern in both the modes of operation by introduction of additional equivalent magnetic currents. Cavity model analysis of a conical annular patch antenna is carried out and is further extended to obtain the multiport network modeling (MNM) of the dual-slot loaded conical annular patch antenna. Additional control over directivity and side lobe level can be achieved by variation in ratio of slot lengths. The effect of curvature on the antenna performance is studied using MNM. The antenna produces a gain of 9.26 and 8.83 dBi in X-band frequencies of 9.838 and 10.323 GHz respectively.

Dielectric Cover Layer Thickness Effect on Circular Microstrip Antenna Parameters

This paper studies the effect of dielectric cover layer thickness on circular microstrip patch antenna parameters such as gain, bandwidth, beam-width, radiation patterns, return loss and VSWR. The proposed antenna is designed with 2.4GHz frequency in S-Band region. This operating frequency useful in ISM band applications. Circular patch antenna is designed with cavity model analysis and simulated using HFSS simulation software (Electromagnetic simulator). The coaxial probe fed is used for antenna design. In this paper the effect of dielectric cover layer on antenna parameters studied experimentally and comparing their performance characteristics. The simulation results shows that the antenna without dielectric cover layer obtained gain is 4.11dB and antenna with dielectric cover the gain is reduced to 2.87dB to 5.88dB based on thickness of the dielectric cover layer. The antenna bandwidth obtained without dielectric cover is 3% and with dielectric cover its bandwidth is reduced from 0.012GHz to 0.052GHz based on thickness of the cover layer effect. Similarly other parameters are investigated and compared. This proposed circular patch antenna is used in wireless and Wi-Fi applications.

A Simple Wide-Bandwidth and High-Gain Microstrip Patch Antenna With Both Sides Shorted

A simple microstrip patch antenna with wide bandwidth and high gain is presented and investigated. It is built on a long rectangular patch with both sides shorted. The antenna is investigated with a cavity model analysis. With a proper design, the TM03 and TM11 modes are excited and combined to achieve a wide bandwidth. In the operation band, the antenna provides a high-gain unidirectional beam around broadside. A prototype is fabricated and measured. Measured results show that the antenna with an overall size of 1.29 λ 0 × 0.73 λ 0 × 0.036 λ 0 ( λ 0 is the wavelength in free space) provides a wide bandwidth of 13.2% (| S 11| < −10 dB). In the operation band, the antenna has a stable high gain varying from 8.0 to 9.7 dBi and a low cross-polarization level of about −25 dB.

Cavity model analysis of differential dual‐polarised annular‐ring patch antenna

The four-port cavity model is presented to study a differential dual-polarised annular-ring patch antenna operating at higher order mode TM12. Acceptable agreements among calculated, simulated, and measured impedances and radiation patterns are obtained. Theoretical analysis shows that the differential port-to-port coupling impedance is zero, and its isolation is theoretically infinite. The differential input impedance is about four times of the single-ended input impedance at the resonant frequency of higher order mode TM12. The differential operation can suppress the adjacent modes TM02 and TM22 near the operating mode TM12 and lead to a more symmetrical E-plane radiation pattern and lower cross polarisation level.

Cavity Model-based Analysis of Field Propagation in a six-port Riblet-type Directional Coupler

ABSTRACTA cavity model-based analysis of electric field propagation inside a six-port Riblet-type directional coupler has been presented in this paper. Though cavity modeling technique is not very new and was previously applied to different rectangular waveguide-based passive networks to find their network parameters, for the first time it has been used here to analyze the field propagation inside a six-port Riblet-type directional coupler. From the analysis, the frequency response of the network has been estimated. Since the main objective of this work is to analyze the field propagation inside a passive network, not to present another network, a six-port Riblet-type directional coupler that is already proposed in literature has been considered. The numerical analysis has been verified by comparing the scattering parameters data obtained from the cavity model analysis with CST Microwave Studio simulation data and measured data available in the literature.

Modeling and Quantification for Electromagnetic Radiation of Power-Bus Structure With Multilayer Printed Circuit Board

The ground bounce noises in a power distribution network of multilayered stack-ups in electronic packages and boards will cause simultaneous switching noise coupling, high insertion loss degradation of signal via, and stray radiation. These lead to signal integrity, power integrity, and electromagnetic compatibility problems. This paper presents an efficient numerical method for evaluating the radiation emission from power-bus structure in complex electronic packaging of high-speed integrated circuit system. It is based on the discretization technique and the boundary integral equation. First, the variational field distribution on the peripheral surfaces of power-bus structure induced by the return current is calculated by using the Helmmholtz equation and boundary conditions. The peripheries of power–ground (P/G) planes and via are discretized into small elements. Then, the changing transient impedance at the edge of antipad plate caused by displacement current through P/G planes is calculated with the assumptive exciting current 1 mA. Finally, the far field radiation is obtained through equivalent magnetic current of edge field. Cavity-model analysis is used to verify, and the good agreement with the theoretical prediction validates the correctness and efficiency of the present analysis.

Cavity model analysis of 30°–60°–90° triangular microstrip antenna

Modal analysis of probe fed 30°–60°–90° triangular microstrip antenna (TMA) is presented using cavity model for TMz mode. Probe excitation is modeled here in three simple ways. A comparative study among these three types of feed modeling is given in a systematic way, hitherto unreported. Input impedance, quality factor, radiation patterns, efficiency, gain are discussed for first five modes. Closed form expressions for calculating the far-field radiation patterns are given here for the first time. New broadside modes are identified and excited successfully, hitherto unreported. Theoretical results are in good agreement with measured data and/or data obtained using 3D EM simulator. It is found that all first five modes show a peak in broadside direction. The results should be useful for practical design of 30°–60°–90° TMA.

Simplified analysis for 30°–60°–90° triangular microstrip antenna

Cavity model analysis is performed for 30°–60°–90° triangular microstrip antenna. Field expressions for various modes are given. Current is modeled as one dimensional ribbon to find the input impedance. Far field radiation patterns for fundamental mode are evaluated using equivalence principle. Results are verified with measures and/or 3D simulated data. It is found that our theory shows close agreement with measured and/or simulated data. It is much less complex and generalized in terms of modal analysis but at the same time more accurate than the other reported analytical techniques for the structure. It is believed that the results can be efficiently utilized to design broad-side 30°–60°–90° triangular microstrip antenna.

CAD Model to Predict the Effect of Radome on the Characteristics of Rectangular Patch Antenna

ABSTRACTA simple CAD model based on cavity model analysis is proposed to compute accurately the resonant frequency, input impedance, and gain of radome loaded rectangular patch antenna. The computed values using present model for wide range of radome parameters are compared with different theoretical and experimental values available in open literature. To validate the present model, we have performed several sets of experiments. The present model shows very close agreements with the experiments compared to the other models. We have also used electromagnetic software (HFSS) to generate simulated data. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:2460–2468, 2013

Design and Analysis of a Low-Profile and Broadband Microstrip Monopolar Patch Antenna

A new microstrip monopolar patch antenna is proposed and analyzed. The antenna has a wide bandwidth and a monopole like radiation pattern. Such antenna is constructed on a circular patch antenna that is shorted concentrically with a set of conductive vias. The antenna is analyzed using a cavity model. The cavity model analysis not only distinguishes each resonating mode and gives a physical insight into each mode of the antenna, but also provides a guideline to design a broadband monopolar patch antenna that utilizes two modes (TM01 and TM02 modes). Both modes provide a monopole like radiation pattern. The proposed antenna has a simple structure with a low profile of 0.024 wavelengths, and yields a wide impedance bandwidth of 18% and a maximum gain of 6 dBi.

Novel Flexible Dual-Frequency Broadside Radiating Rectangular Patch Antennas Based on Complementary Planar ENZ or MNZ Metamaterials

A novel scheme of designing dual-frequency broadside radiating rectangular patch antennas is proposed. Cavity model analysis shows that, by partially loading Lorentzian dispersive epsilon-near-zero (ENZ) or mu-near-zero (MNZ) metamaterials (MTM), the electric fields at two radiating edges of the patch antennas can be out of phase and a broadside radiation pattern can be achieved at both operating frequencies. With proper constitutive parameters and filling ratio, the frequency ratio (FR) of the dual-frequency antenna can be flexibly chosen in a very wide range. Experimental results of a double positive (DPS)-MNZ based dual-frequency patch antenna, with its MNZ practically implemented by a complementary electric-LC (CELC) array etched on the patch surface, demonstrates the validity of such scheme. A detailed design procedure is also described. Compared to some conventional and other MTM based techniques, the proposed dual-frequency solution shows its advantages on excellent broadside radiating pattern with low cross-polarization and reduced back lobe, FR flexibility, and ease of fabrication.

Characteristics of circular patch antenna with and without air gaps

The characteristics of circular patch antenna (CPA) with and without air gaps in between substrate and ground plane are thoroughly investigated. We present a set of closed-form expressions based on cavity model analysis to predict accurately the characteristics of CPA with and without air gaps. The proposed model is valid for both coaxial-fed and microstrip line-fed CPA operated in dominant and higher order modes. The computed values for wide range of antenna parameters, feed locations, and air gaps are compared with different experimental and theoretical values available in open literature. The present model is fast, simple, and closer to the experiments compared with the other models. We have also used a simulator to validate the present model. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1692–1699, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26917

Optimization of Printed Antennas Using Genetic Algorithm Coupled with Improved Cavity Model

AbstractAn accurate electromagnetic optimization tool for designing rectangular and circular microstrip antennas is proposed. This optimization method is based on the improved cavity model analysis in conjunction with the well-known genetic algorithm, which is employed to optimize the dimensions and feed point location of rectangular and circular microstrip antennas. Results obtained by this technique agree quite well with the measured data and the data obtained by the FEM based software HFSS by ANSOFT. This technique can be fruitfully used in microwave CAD applications.

THEORETICAL INVESTIGATION OF RECTANGULAR PATCH ANTENNA MINIATURIZATION BASED ON THE DPS-ENG BI-LAYER SUPER-SLOW TM WAVE

The TM0 surface mode in an infinitely long parallel-plate waveguide filled with a double-positive (DPS) and epsilon-negative (ENG) metamaterial bi-layer is studied. With proper constitutive parameters and thicknesses of the two layers, the slow-wave factor (SWF) for such a parallel-plate waveguide can tend to infinity as the frequency decreases. A 2-D cavity based on the DPS-ENG bi-layer waveguide is constructed and studied to evaluate the radiation ability of its corresponding patch antenna. Based on the cavity model analysis of patch antennas, we show that good efficiency for broadside radiation of such a cavity-based rectangular patch antenna can be achieved when one layer of the cavity is shielded (or partially shielded) by PEC boundaries. Taking practical loss and dispersion into consideration, a miniaturized cavity-based rectangular patch antenna is proposed as an example. With the super-slow TM0 surface mode excited in the bi-layer by a simple coaxial line feeding, the antenna has a dimension of only 0.107λ0×0.129λ0×0.045λ0. The patch antenna produces broadside radiation, and fairly good radiation efficiency is achieved. The PEC-Partially-Shielded-ENG-Cavity based rectangular patch antenna with a further miniaturization but reduced radiation efficiency is also discussed. (Less)

CAD MODEL TO COMPUTE THE INPUT IMPEDANCE OF AN EQUILATERAL TRIANGULAR MICROSTRIP PATCH ANTENNA WITH RADOME

A very simple and more e-cient CAD model is proposed to demonstrate the efiect on input impedance characteristics based on cavity model analysis for wide range of superstrate parameters and feed locations of an equilateral triangular microstrip patch antenna having difierent side lengths. The computed values are compared with difierent theoretical and experimental values available in open literature, showing close agreement. A Maxwell's equation solver is also used to validate our model.

Design of WiFi/WiMAX dual‐band E‐shaped patch antennas through cavity model approach

AbstractThe design of dual‐band, single patch microstrip antenna covering 2.4 and 3.5 GHz for WiFi and WiMAX applications based on E‐shaped patch is presented. Although cavity model analysis is included in the design procedure, the slotted configuration is treated as the perturbed cavity to characterize the resonant frequencies of corresponding modes. Additionally, the feed point position is determined through the field distribution resulted from the modal analysis. A new equivalent circuit model based on the coupled resonators theory is proposed for analysis purposes. The relationship between cavity model analysis and antenna resonances is further evidenced by the surface current distributions on the conductors. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 471–474, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24954