All antennas
A simulation of a planar Square Loop Antenna (SLA) on a Hybrid High Impedance Surface including the feeding part using a 4 way Wilkinson power divider is shown in this article. Placing the planar antenna over a hybrid High Impedance Surface (HIS) can lower the overall antenna profile due to the unique reflection phase of the HIS. The planar SLA produces a semi doughnut radiation pattern which is suitable for vehicular communication. The effect of the feed network and cables on the antenna performance is considered.
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This paper is based on: "Comparison of electromagnetic field solvers for the 3D analysis of plasmonic nano antennas" by Johannes Hoffmann, Christian Hafner, Patrick Leidenberger, Jan Hesselbarth, Sven Burger, Proc. SPIE Vol. 7390, pp. 73900J-73900J-11.
The Field Distribution inside a 1 nm wide gap between two 80 nm diameter Gold spheres is calculated and compared to a semi analytical reference solution published in the paper. Both general purpose solvers of CST MICROWAVE STUDIO® are used. The simulation results agree closely with the reference solution.
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Electromagnetic simulation of anechoic chambers is a very difficult task. Gwenaël Dun, R&D Engineer for Siepel, used a variety of different electromagnetic simulation tools to address this challenge in the past but ran into problems with both poor accuracy and long compute times. He then worked with the developers of CST MICROSTRIPES™ electromagnetic simulation software, to implement a feature that makes it possible to model the ferrite absorbers used in the chamber as a boundary condition rather than part of the computational domain. This change made it possible to increase mesh size by a factor of 15, reducing compute time by more than 95%. The simulation results provided a near-perfect match to physical testing.
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The dielectric lens antenna has been developed and applied for measuring the tank filling level in the industrial storage tank. A compact antenna with high beam is required in this application field, since the size of the antenna is limited by the size of the flange. This dielectric lens antenna has been simulated and optimized using CST MWS Transient domain solver and it shows a good agreement with the measurement.
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The telecommunications sector is making great advances aimed at delivering an even stream of high tech devices, covering the significant consumer demands in this sector. EM simulation is increasingly becoming an indispensable tool in the design flow, not only on the antenna level but also on the phone and environmental levels. This article compares simulated results with measurements for several steps in the phone design chain.
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Tim Herrmann, Johannes Mallow, OvG University Magdeburg
Magnetic resonance imaging (MRI) is one of the most important non-invasive examination methods in the modern medicine. To raise up examine possibilities, MRI systems with more powerful magnetic fields are constituted. The standard high-field whole body (1.5T-3T) MRI Systems (Fig. 1) are using a body coil for the excitation. MRI at ultra-high-field (UHF) requires different Tx-coils for excitation of different body parts since the construction of one large body coil, similar to those at lower fields, is to difficult. Moreover, at 7T B1 is inhomogeneous as the RF-wave length within the object is smaller than the object extensions. While in RF-coils the usable B1-field is restricted to dimensions and geometry of the RF-coil itself, with the new travelling wave concept, described by Brunner [1], the usable B1-field is restricted to the dimensions of the waveguide (RF-shield) only. Thus the MR travelling wave concept allows excitation of large volumes depending on the length of the RF-shield. For an antenna with a frequency of 297MHz the approximate wavelength is about 1m. Thus the RF-shield of the gradient coil with a diameter of 64cm can be used as a waveguide, because of the cut-off frequency. The cut-off frequency is the minimum frequency where a wave fits into the waveguide without damping. This study examines the use of the travelling wave concept as an efficient body coil replacement in UHF MRI-System with the support simulations in CST Microwave Studio 2009 and measurements. Therefore two different types of antennas have been simulated and produced. The B1-field distribution of a dipole and a patch antenna where simulated and compared with B1-field measurements in a 7T MRI System. The efficiency compared to a 1.5T body coil was investigated. Further research goals are to create biological models based on anatomical MRI-Dataset for use in field-simulation software with dynamic thermal solver for more realistic SAR calculation. However the remaining problems of exposing sensitive body parts, such as the human head by increased SAR needs to be solved for next generation UHF MRI-Systems.
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Yael Kaldor, Rafael
This work describes the simulation and optimization processes of a small antenna located on a large platform. (The platform size is 13? x 3? x 3?). The required antenna frequency performance is wideband and it is required to perform under severe environmental conditions. The antenna structure was modeled and simulated using CST (MWS) for return Loss and Radiation Pattern performance. The antenna model was parameterized to allow future optimization. The Return Loss specification for the Antenna was -8 dB maximum (VSWR 2.2:1) over a 30% bandwidth. Simulated Return Loss was initially poor over the full frequency range (sufficient performance was obtained over 6% bandwidth only). See Figure 1. The Antenna model was optimized using Mode Frontier for Return Loss performance over the full frequency range. The optimization results are depicted in Figure 2. The Return loss and VSWR performance were highly improved using the optimization process. 34% bandwidth was obtained.
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Joost ter Laak, JTL Engineering B.V.
VBA programming was used to create a fully parametrised design in MWS of a RF module containing matching circuits and antenna for a RF module to be used in a game controller. The complete module was modelled in MWS and the design trade-offs were investigated by varying different parameters.
Using this VBA program it became easy to create different designs and optimize interesting parameters for board size and performance. The design was fabricated and found to behave according to the simulation results, no second spin was needed. The design will be used in mass production.
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Floc’h Jean Marie, IETR
The antenna is used with UWB Radar techniques in order to locate buried alive victims. The detection is based on the signature of alive persons by using Doppler analysis of movements and respiration. Detecting victims in this environment is very difficult due to the large dynamic range of signal levels. In fact, the reflected signal caused by the buried alive victim is very low behind other reflected or disturbing signals such as mobile phones, vegetation movements, water, rescuers… A two flares UWB antenna, light weight and easy transportable has been specially design for the research of buried victims beneath building rubble. This paper focuses on antenna design, simulation using CST software and measurement. These measurements have been made by IETR and CEA. The experimental results show a good comparison between measurements and simulations. The goals for the design were:
- Frequency band: 300 MHz – 3 GHz
- Compact antenna
- Gain around 10 dBi at the center frequency
- Low back side radiation
- Good impulse response
- Very light weight antenna
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Marcello Zolesi, Thales Alenia Space
The scope of the present work is to analyze the effective coverage of TT&C subsystem of a LEO satellite at an altitude of 700 kilometres. The antenna assembly is made of two units, Main and Fill-In Antennas, accommodated on opposite sides of the spacecraft. Starting from the free-space radiation performance of each of the two antennas, the problem to predict the global TT&C subsystem radiation pattern in presence of the spacecraft is treated in order to identify potential blind areas or interferences caused by the neighbouring structures. The prediction of electromagnetic field scattered in complex environment is usually a hard task since the solution cannot generally be expressed in a simple and/or closed analytical form. Therefore a variety of numerical methods have been developed in literature. The effectiveness of a single method depends on the type of the electromagnetic environment and the working frequencies. The calculations of the global TT&C subsystem radiation pattern in presence of the main spacecraft structures are carried out by means a full-wave electromagnetic software, CST Microwave Studio Integral Solver. The Integral Solver is ideally suited for electrically large structures respect to the wavelength, when dominated by electrical conductors. This solver uses a combination of an open boundary integral formulation and a Multilevel Fast Multi-Pole Method (MLFMM) exhibiting an optimal complexity in terms of memory and simulation time compared to the traditional Method of Moment (MoM). Key-words: Coverage, EIRP, MLFMM, MoM, TT&C antennas.
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Hubregt J. Visser, PhD, Holst Centre – IMEC-NL
Antennas, when brought into close proximity with RF reflective objects or lossy human tissue,
will show a degradation in performance. This degradation is visible in the input impedance as a
function of frequency and in the radiation pattern, gain and efficiency. In the presentation we will
show two examples of miniature antennas designed for on-body use that exhibit a negligible
performance degradation when brought near or onto the human body. One of the examples
comprises a miniature, curved microstrip patch antenna for application on the wrist, see Figure 1.
Here, the ground plane of the patch antenna has been used to form a shielding between antenna
and environment. The other example is a CPW printed monopole antenna, embedded in a low-loss
dielectric body to contain the fields and thus minimize reactive tuning, see Figure 2. Furthermore the
short ground plane of this antenna has been modified to suppress coaxial cable current radiation. In
the designs, the human body has been modeled as a curved, layered medium consisting of skin, fat,
muscle, bone and, when appropriate, dura, cerebrospinal fluid and brain tissue. The CSTMWS designs,
the realized prototypes and the measurement results will be presented.
Figure 1: Curved microstrip patch antenna
for use on the wrist.
Figure 2: Printed monopole antenna in
proximity to the human body.
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This article concerns the design of a X-Band squintless horn antenna array consisting out of 96 radiating elements. The full design of the 2.4m antenna blank (including the simultaneous excitation of all 96 arms) has been performed within CST MICROWAVE STUDIO®. The simulated results have been in an excellent agreement with compact range measurements.
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This paper presents the excellent correlation of measurement results to the numerical calculations of a SATIMO dual-ridge horn antenna which include the directivity, boresight gain, and return loss vs. frequency. The structure is electrically large which lends itself, as a result of its efficient memory utilisation, to the CST MICROWAVE STUDIO® (CST MWS) Time Domain Solver. Broadband, high resolution gain results can be obtained within a single run with as many as 100 farfield monitors being defined.
The results are presented with the courtesy and permission of SATIMO, Italy.
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Richard Roberts, Astrium Ltd
This presentation describes how CST Microwave Studio (MWS) has been used in conjunction with POS 5 and GRASP 8 to design an X-Band circularly polarised Splashplate Antenna. The antenna essentially consists of a centre fed reflector (17 wavelengths in diameter), the Splashplate feed (~2 wavelengths in diameter), and a septum polariser to allow the Tx and Rx bands to operate in opposite polarisations. A significant factor in the design is that a short circuit had to be assumed at the other port of the septum polariser meaning that the return loss of the Splashplate feed and the reflector were critical to the axial ratio performance. CST MWS enabled this aspect of the design to be modelled and analysed using the T-solver. Comparison of the measured and predicted antenna performance has validated the design process. Although a compliant performance has been achieved, it is evident that some modelling improvements could be sought in order to get a better convergence between prediction and measurement.
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Sebastian Sczyslo, Gunnar Armbrecht, Holger Thye, Sven Dortmund, Thomas Kaiser, Leibniz Universität Hannover
This contribution deals with the accurate determination of the impulse response of Ultra-wideband (UWB) antennas both by simulation and measurement. As can be found in recent literature, knowledge about the impulse response does not only allow for the derivation of further antenna parameters such as gain or group delay, but also to design more efficient receivers and to run more realistic simulations. Here we will exemplarily use the cone antenna as the antenna under test (AUT), as this is a very prominent antenna type in the field of UWB. In the first part CST Microwave Studio (CST MWS) is used to model and simulate the antenna in the transmit case. To extract the radiated E-Field, we developed a new macro based on the transient broadband farfield monitor. Applying this macro is time-saving compared to the conventional method using farfield probes which can be found in many publications. The transmit impulse response is determined by a deconvolution operation. Finally Lorentz reciprocity is used to evaluate the receive impulse response as it is common in literature. In the second part the obtained simulation results from CST MWS will be compared to measurement results. At this we will not only use the conventional two-antenna method but we will also introduce the GTEM method, as a fast and accurate antenna measurement method. We developed this novel method based upon our previous research in the field of GTEM cells and it allows for a direct determination of the receive impulse response using a single antenna only.
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Ad Reniers, Technical University Eindhoven
High-data-rate wireless communications need wide bandwidths. In the Ultra-Wideband (UWB) frequency band from 3.1 GHz to 10.6 GHz, information may be spread over a large bandwidth at low power levels thus creating the possibility to share the spectrum with other users. To prevent interference with existing wireless systems, like IEEE 802.11a WLAN, stop band characteristics are required from 5 GHz to 6 GHz*. The notch filter function is designed in a low-cost circular planar dipole antenna based on the ‘two-penny’ dipole. To achieve the required specifications for this notch function we used first the CST optimizer. After that we optimized systematic the design. In this presentation we want to show the results of both approaches to achieve a maximum result and try to understand the working of this notch and spur function in this compact UWB antenna.
* Paper: Low-cost, compact UWB antenna with frequency band-notch function. H.J. Visser.
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Transmitters used in vehicle environments present potential threats to the health and safety of vehicle users, in terms of both human exposure to electromagnetic fields and vehicle EMC (electromagnetic compatibility). The recently revised automotive EMC directive (2004/104/EC) now requires vehicle manufacturers to identify acceptable frequencies, powers and antenna installations that can be used on vehicles without compromising their EMC performance.
The simulations presented here were performed with CST MICROSTRIPES™.
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Human head models like the SAM phantom are already regularly used to test the influence on mobile phone performance as well as to check the compliance to SAR standards. However, the hand also influences the field distribution significantly. The following article shows the CST MICROWAVE STUDIO® (CST MWS) simulation results of a complete Sony Ericsson mobile phone in relation to head and hand phantoms.
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Radio Frequency Identification Systems (RFID) are widely used and allow advanced solutions for a variety of applications in the area of authentication, ticketing, access control, supply management, parking, payment, vending,etc. The example presented here is a RFID Readercoil "P81" from Legic Ident Systems and was modeled and solved using the frequency domain solver of CST MICROWAVE STUDIO® (CST MWS). The sensitivity of the computed complex input impedance with respect to substrate tolerances is computed and was compared to measurement data.
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Radio Frequency Identification Systems (RF-ID) are widely used and are thus one of the fastest growing sectors of todays radio industry, allowing advanced solutions for a variety of applications in the area of authentication, ticketing, access control, supply management, etc. One of the most common band allocated to RFID systems is 13.56 MHz. For this application example operating at this particular frequency band we have chosen a transponder inlay which was created using the ACIS based solid modeler of CST MICROWAVE STUDIO® The frequency domain solver of CST MICROWAVE STUDIO® has been applied to accurately predict the input impedance, followed by a lumped element based equivelent circuit derivation to describe the impedance versus frequency.
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J.Fejfar, CST of America. Video of a webinar presentation (Running time: 11 min)
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J. Guerci , Consultant, VA, USA. Video of a webinar presentation(Running time: 33 min)
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K. Carrigan, Senior Systems Engineer, U.S. Navy (NSWC Dahlgren), & D. Johns, CST of America. Video of a webinar presentation (Running time: 32 min).
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A UWB dipole antenna composed of circular arms containing a special feeding system is modeled simulated using CST MICROWAVE STUDIO®, the results of which are presented in this article. The design, developed by IETR-INSA / Thomson R&D France, shows good broadband matching (3-10 GHz) and an omnidiectional radiation pattern up to 6 GHz.
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A multiple band-notched planar monopole antenna for multiband wireless systems is presented. The proposed antenna consists of a wideband planar monopole Antenna and the multiple U-shape slots, producing band-notched characteristics. This technique is suitable for creating ultra-wideband (UWB) antenna with narrow frequency notches or for creating multiband antennas. Various antenna configurations were simulated with CST MICROWAVE STUDIO®.
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This article concerns the application of CST MICROWAVE STUDIO® (CST MWS) to the simulation of electrically large automotive structures. CST MWS is ideal for such applications since the geometry can be easily imported and modified using the powerful user interface, the accurate and robust PERFECT BOUNDARY APPROXIMATION (PBA)® approximation is exploited, the linear scaling of memory with increasing mesh cells and the ability to simulate broadband in one single simulation. An example of an on-glass antenna simulation is also demonstrated highlighting the versatility of the CST MWS Transient solver.
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For a customer given corrugated horn the phase center has been computed using CST MICROWAVE STUDIO® and compared with measurement data. The simulated results are in very good agreement with measurements. Measurements were provided with courtesy and permission of Kathrein Werk KG, Rosenheim, Germany.
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An RFID Reader Antenna with the following specifications was designed:
- Frequency: 908.5 - 914 MHz (In Korea)
- VSWR: less than 2 with 50-ohm impedance
- Polarization: circular
- Axial ratio: less than 3 dB @ 908.5 - 914MHz
- Gain: 6 dBi @ 1W transmitted power
- Size and weight: as small as possible
This article is published with the permission and courtesy of Prof. Bierng-Chearl Ahn and his colleagues at Chungbuk University, Korea.
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The behaviour of a ferrite loaded waveguide antenna is predicted first by a 2D-analytical model and second by CST MICROWAVE STUDIO®. The results of the predictions are compared with measurements. (Courtesy and permission of KAIST Korea.)
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This article demonstrates the application of CST MICROWAVE STUDIO® (CST MWS) to the analysis of large reflector feed arrays. An array consisting of 19 elements was simulated but a larger array of more than 100 elements may also be simulated since the memory scaling with mesh cells in CST MWS is almost linear. The simultaneous excitation feature in CST MWS was applied to obtain farfield patterns in just a single simulation. A parameter sweep was also carried out to obtain the S-Parameters as a funtion of element feeding postion.
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In this article a single periodic open-ended waveguide phased-array antenna with a dielectric radome at its aperture of variable thickness is analysed. As a verification it is shown that the superposition of two independent plane waves shows the same field pattern as the one created by the unit cell model.
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A standardized spherical phantom head such as the one described in this example is commonly used for SAR investigations and measurements.
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Nearly full-sized performance from a spherical coil only 1/6th as long in the E-plane normal direction as a half-wave dipole antenna.
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CST MICROWAVE STUDIO® has been succesfully applied to the simulation of a wide-band dual-mode horn antenna which exhibits a rotationally symmetric beam and low side-lobe levels.
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In this article the new I! Solver of CST MICROWAVE STUDIO® is used to calculate the input impedance of a monopole antenna on a conducting box. This simple example demonstrates the accuracy of the Integral Equation Solver.
Geometry and results are from the paper "The Input Impedance of a Monopole Antenna Mounted on a Cubical Conducting Box“ by Shyamal Bhattacharya, Stuart A. Long, Donald R. Wilton. IEEE Transactions on Antennas and Propagation, Vol. AP 35, No. 7, July 1987. The
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This article demonstrates the simulation of an electrically large antenna. The design and numerical results are courtesy and permission of Chelton Antennas, France. The antenna operates at 8 GHz and was simulated using the CST MICROWAVE STUDIO® Transient Solver which is, as a result of its efficient memory scaling, ideal for such electrically large structures - the dish diameter in this example is approximately 20 wavelengths in size.
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The article presents an antenna-based approach to near-field imaging and spectroscopy, which can be used for both continuous-wave and pulsed broadband electromagnetic radiation from microwave to terahertz frequencies. CST MICROWAVE STUDIO® (CST MWS) was used to perform the simulations.
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This note shows simulation results for a printed Dipole Antenna with integrated Balun. The design is based on the article "3-D FDTD Design Analysis of a 2.4-GHz
Polarization-Diversity Printed Dipole Antenna With Integrated Balun and Polarization-Switching Circuit for WLAN and Wireless Communication Applications" by Huey-Ru Chuang, and Liang-Chen Kuo, IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, VOL. 51, NO. 2, FEBRUARY 2003
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Microwave Engineering Europe's (MWEE) EM simulation benchmark has become quite a tradition over the last few years, enticing some of the best known software providers to put their diverse simulation methods to the test.
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This huge Pillbox Antenna was optimised by one of our customers even during the evaluation period of CST MICROWAVE STUDIO
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