Computer Simulation Technology Microwave Research Articles

Design and Analysis of a PDLC-Based Reconfigurable Hilbert Fractal Antenna for Large and Fine THz Frequency Tuning.

The proposed reconfigurable radiating antenna design is based on the integration of a reconfigurable fractal antenna and electro-optic substrate material. This antenna can be adjusted to achieve either re-configurability or tunability in the desired frequency range for wireless systems. The electromagnetic characteristics of the fractal antenna are manipulated at both the level of fractal geometry, electrical length and dielectric substrate. The designed antenna features multiband responses, in which the geometry and length change create a large frequency shift and the dielectric change using polymer dispersed liquid crystal (PDLC) creates fine and/or continuous tuning. The far field and scattering properties of the antenna are analyzed using the Computer Simulation Technology (CST) Microwave Studio Suite. The proposed approach has successfully demonstrated reconfigurable switching for up to four frequency bands between 0.2 and 0.6 THz. The dielectric constant change in the PDLC substrate shows fine and continuous frequency tuning with an 8% maximum frequency shift when operating around 0.54 THz and a high directivity of 7.35 dBi at 0.54 THz and 8.43 dBi at 0.504 THz. The antenna can also realize a peak gain of 4.29 dBi at 0.504 THz in the extraordinary polarization state of PDLC. The designed antenna can be readily integrated in the current communication devices, such as satellites, smart phones, laptops, and other portable electronic devices, due to its compact geometry and IC compatible design. In satellite applications, the proposed antenna can play a significant role in terms of security. The antenna could be extremely useful for satellites that want to keep their information secret; by constantly switching their operating frequency, spy satellites can evade detection and data collection from enemy ears.

Analysis of multiband rectangular patch antenna with defected ground structure using reflection coefficient measurement

<p class="Abstract">In this paper, a novel quad band antenna to operate at four different frequency bands is designed and simulated using Computer Simulation Technology (CST) Microwave Studio software. To achieve better performance of the antenna, various parameters were optimized using parametric analysis. During this analysis, various antenna parameters were need to be measured. The proposed antenna uses asymmetrical ‘U’ and ‘T’ shaped radiating elements printed on an FR-4 substrate with dimensions of 1.6 × 34 × 20 mm<sup>3</sup>. The measurement of various antenna parameters like reflection coefficient, return loss, radiation intensity are key tasks to be performed in the antenna measurement laboratory before going to the real time application. A stair case defected ground structure with rectangular center slot is used to attain a better bandwidth. The antenna resonates at four different frequencies 3 GHz, 4.8 GHz, 9 GHz, 13.2 GHz with operating bandwidths of 980 MHz, 2.05 GHz, 3.84 GHz, and 3.82 GHz respectively. The S<sub>11</sub> value at these resonant frequencies is measured as -23.6 dB, -29.4 dB, -34.2 dB, -49.05 dB respectively. The voltage standing wave ratio of the proposed antenna at four resonant frequencies is equal to one. The gain of the antenna is consistent throughout the four pass bands. The antenna is suitable for Bluetooth (2.4) GHz, WLAN (5.125-5.35) GHz and (5.725-5.825) GHz, WiMAX (5.25-5.85) GHz, C-band (3.7-4.2) GHz and Ku-band (12-18) GHz.</p>

Specific absorption rate reduction for sub-6 frequency range using polarization dependent metamaterial with high effective medium ratio

This research study introduces a multi-layered square-shaped metamaterial (MSM) structure for the electromagnetic (EM) absorption reduction in wireless mobile devices. Usually, wireless devices, for example, a cellular phone emits radiofrequency (RF) energy to the surroundings when used it. Moreover, fast-growing wireless communication technologies that support cellular data networks have also motivated this study. Hence, the focus of the research was to reduce the Specific Absorption Rate (SAR) for the Sub-6 frequency range by designing a multi-layered and compact, 10 × 10mm2 sized metamaterial structure that can be attached inside a mobile phone by avowing any overlapping with existing parts. Overall, six distinct square-shaped metamaterials were constructed on 0.25 mm thick Rogers RO3006 substrate material to reach the target of this investigation. Furthermore, numerical simulations of the proposed metamaterial electromagnetic properties and SAR reduction values were performed by adopting Computer Simulation Technology (CST) Microwave Studio 2019 software. From these simulations, the proposed MSM structure exhibited multi-band resonance frequencies accurately at 1.200, 1.458, 1.560, 1.896 GHz (at L-band), 2.268, 2.683 2.940, 3.580 GHz (at S-band) and 5.872 GHz (at C-band). Simultaneously, the proposed MSM structure was simulated in High-Frequency Structure Simulator (HFSS) to authenticate the numerical simulation data. The comparison of simulation data shows that only the primary and last resonance frequencies were reduced by 0.02 and 0.012 GHz, whereas the rest of the frequencies were increased by 0.042, 0.030, 0.040, 0.032, 0.107, 0.080, and 0.020 GHz in sequential order. In addition, the introduced MSM structure manifests left-handed behaviour at all the resonance frequencies. Nevertheless, the highest recorded SAR values were 98.136% and 98.283% at 1.560 GHz for 1 g and 10 g of tissue volumes. In conclusion, the proposed MSM met the objectives of this research study and can be employed in EM absorption reduction applications.

A THEORETICAL STUDY TO DESIGN A MICROWAVE RESONATOR FOR SENSING APPLICATIONS

This paper presents a microwave sensor design for moisture detection contents in petroleum productions based on metamaterials. The proposed sensor occupies a compacted size of 40×40×1.6 mm3 by using low-cost FR4 substrate. The proposed sensor consists of a transmission line and two split-ring resonators (SRRs) mounted on two sides. The transmission line is coupled to the outer ring of the SRRs to provide two resonant frequencies at 1.03 GHz and 3.04 GHz. It is observed that most of the electric fields fringing is come out of the air gap on the SRRs. Two pans are mounted on the sensor to contain the sample under test (SUT). The simulation studies are carried out by using the Computer Simulation Technology (CST) Microwave studio. After introducing the pans, frequency shifts, △f1=150 MHz and △f2=424 MHz, are detected in the resonant frequency which is associated with the perturbation phenomenon when the water concentration is varied from 0% to 100%. The proposed sensor exhibits a reliable detection percentage of various different amounts of the moisture content in crude oil introductions. Generally, a good detection methodology is discovered by applying the proposed sensor for detecting the crude oil quality productions.

DESIGN OF BROADBAND AND POLARIZATION-INDEPENDENCE METAMATERIAL ABSORBER USING A CHIRAL STRUCTURE WITH CONDUCTIVE POLYMER

We present a simple approach to enhance the bandwidth and absorptivity of the metamaterial absorber (MA) in the GHz region. The proposed MA is designed and simulated by computer simulation technology (CST) Microwave Studio. The results indicate that the absorption of the MA strongly depends on the conductivity of the polymer. By using a chiral structure with the low conductive polymer of 700 S\m, the absorption bandwidth is expanded up to 12.9 GHz (relative bandwidth of 85.7%) with absorptivity over 80%. It exhibits polarization-independent absorption and can be applied to fabricate broadband MA.

Investigation on Electromagnetic Properties of PLA/Carbon/Copper Antennas for Breast Cancer Detection

Breast cancer is the most common cancer of women in the globe. Microwave imaging has low power and longer wavelength signals to receive information about breast tissues and guarantees a safer and more accurate modality for regular breast control. So, the antenna is a crucial element in the microwave imaging system. This study involves analysis of the simulation results of the linear and planar microstrip array antennas in terms of high gain. In the series antenna design stage, the antenna models with high gain and directional radiation are aimed. 1x4 and 2x2 array antenna models are prepared with PLA/Carbon insulating material. Array antennas, three-dimensional full-wave electromagnetic structure analysis are designed using the CST (Computer Simulation Technology) Microwave Studio program. In the design phase, the transmission line losses of the array antennas are tried to be optimized by using T-junction and Wilkinson power divider techniques and impedance matching is realized. Also, the redundant areas in the turns are removed to minimize the undesirable reflections in the transmission line and to reduce the capacitive loading. Since the 1x4 array antenna performs better than the 2x2 array antenna, it was preferred for breast cancer simulation.

Wideband millimeter-wave substrate integrated waveguide cavity-backed antenna for satellites communications

This paper presents a new type of wideband waveguide (SIW) cavity-backed patch antenna for millimeter wave (mmW). The antenna proposed applies to applications of 31-36 GHz Ka-band such as satellites communications. The SIW is intended with settings for particular slots. The antenna is constructed on Rogers RT5880 (lossy) with 2.2 dielectric constant, l.27 mm thickness, and 0.0009 loss tangent. It is simulated in the programming of computer simulation technology (CST) Microwave Studio. The simulated results show that the SIW antenna resonates across 31 to 36 GHz bands, which means that this new antenna covers all applications within this range. The reflection coefficients in targeting range are below 10 dB. The antenna achieves good efficiency and gain with 80% and 8.87 dBi respectively.

Investigation of a novel solid-state dual meander pulse-forming line with 10 kV-class withstand voltage

The meander pulse-forming line (MPFL) is one kind of prospective solid-state device for compact, reliable pulsed power systems. This paper demonstrates that a dual meander pulse-forming line (DMPFL) further improves its withstand voltage upon previous MPFLs by optimizing the distribution of the fringing electric field around the electrodes to mitigate the field enhancement. The DMPFL is formed by connecting two MPFLs in parallel on a glass-ceramic substrate. The dispersion characteristics of the DMPFL including its characteristic impedance and electric length are analyzed. Then, the delay time and pulse-forming characteristics are simulated with computer simulation technology (CST) Microwave Studio software. On this basis, experiments are performed to investigate its practical withstand voltage and pulse-forming ability. The experimental results agree with the calculation and simulation results. At last, we tried to integrate the Blumlein module based on the DMPFL with the photoconductive semiconductor switch to form a compact solid-state pulse generator.

Reflection based Strain Sensing using Metamaterials

Resonator arrays of periodicially arranged electromagnetic sub-wavelength resonators show a strong frequency filter behaviour which can be controlled by the geometry, size and arrangement of the resonators. The use of several resonator arrays and their integration into a polymer matrix allows the realisation of metamaterials with a specific resonance behaviour. The resonance behaviour can be influenced by material and structural changes enabling a passive sensor function. The considered sensor approach based on metamaterials is investigated to enable structural health monitoring of lightweight structures. In the present case, a double-layer Jerusalem cross (JC) resonator array (RA) is integrated into a glass fibre reinforced plastic (GFRP) to analyse the change of the resonance behaviour under load (strain) using a reflection measurement. The CST (Computer Simulation Technology) Microwave Studio was used to model the resonator array for operation in the microwave frequency range between 15 GHz and 35 GHz as well as for the numerical analysis of the resonance behaviour under load. The numerical results were validated by a tensile test using a tensile test machine (type TIRATEST 28100, Tira GmbH) and by a reflection measurement using two standard gain horn antennas (type Standard Gain Horn Series 862, ARRA Inc) and a vector network analyser (type ZVA50, Rohde&Schwarz). The reflection measurement shows a reflection minimum at 28.6 GHz which moves to higher frequencies under load of the GFRP laminate. With the shift of the minimum, the quality factor decreases and the dip widens. The investigation shows that it is possible to provide a GFRP laminate with a specific electromagnetic behaviour by integrating resonator arrays. It is also shown that the specific electromagnetic behaviour can be influenced by structural changes and thus opens up the possibility of monitoring the condition of lightweight structures.

Design of H-Tree fractal slots frequency reconfigurable hexagonal patch antenna using PIN diodes

ABSTRACTIn this paper, a frequency reconfigurable hexagonal patch antenna with the ability to operate in L and S bands is been presented. This patch incorporates a H-Tree fractal slot on the patch and ground plane of the resonating element with five (5) PIN diodes integrated on the antenna surface to change the current distribution which consequently changes the resonance frequency under different conditions of switches, thereby making it a frequency reconfigurable antenna. The proposed patch antenna allows reconfigurable switching in multiple frequency bands between 1 and 3 GHz, with relative narrow bandwidths. Computer simulation technology (CST) microwave studio software is used to analyze the design and it’s fabricated on a Rogers R4350 substrate (0.508 mm thickness) with an area of 63 mm × 69.75 mm. Both simulation and measurement have shown good agreements with each other, satisfying the requirements for Bluetooth, GSM and WLAN antenna applications.

Classes of non‐resonating‐node lowpass prototype networks suitable for realisation as evanescent‐mode waveguide bandpass filters

This work presents four classes of lowpass prototype networks comprising non-resonating-nodes (NRNs) realising generalised elliptic function transfer characteristics. Each class of networks can realise a maximum of ( N - 2) finite-frequency transmission zeros where N is the total number of the resonators in the network. The distinct feature pertinent to the proposed classes of networks is that they can be sub-classed into two types: type I networks have positive frequency-invariant elements (FIEs) located at the NRNs, and type II networks have negative FIEs located at the NRNs. type I networks are particularly suitable for the realisation as evanescent-mode waveguide (EMW) bandpass filters which is the main subject of this work, whereas type II networks could be realised as waveguide bandpass filters operating above the cut-off of the guide. Numerical examples of the four classes of the proposed networks are presented. The proposed circuit concepts are validated through the realisation of two classes of filters in EMW technology created utilising computer simulation technology (CST) microwave studio. The electrical performance of the CST filter structures and their circuit counterparts are in close agreement.

Improving radiation performance of extremely truncated RCAs through near‐field analysis

This paper studies the cause of low-broadside directivity and high sidelobe levels (SLLs) in compact resonant-cavity antennas (RCAs) (footprint < 8 λ 0 2 ). An approach to determine an optimal near-field distribution to significantly improve the broadside directivity and SLL of RCAs is presented. A near-field to far-field transformation routine developed in MATLAB is used to study the individual effects of amplitude and phase distributions, above the partially reflecting superstrate (PRS) of RCAs. Unlike the direct use of a full-wave simulator design, this new approach allows the designers to understand the individual effects of amplitude and phase distributions in the radiating near-field region, on the broadside directivity and on the SLL in the far-field radiation pattern. A method to realise a desired complex near-field distribution is demonstrated, using a dielectric PRS. The RCA with the new PRS showed a significant improvement of 5.0 and 6.4 dB in the broadside directivity and SLL, respectively, compared with a uniform PRS without compromising the footprint and profile of the antenna. The predictions of MATLAB are validated using computer simulation technology (CST) microwave studio (MWS) and experiments

Realization of strong backscattering homogeneous regions with known backscattering coefficient in synthetic aperture radar images

Shanghai Jiao Tong University, Department of Electronic Engineering, 800 Dongchuan Road,Shanghai 200240, ChinaAbstract. The strong backscattering homogeneous region,i.e., auniform regionwith ahigh andconstantbackscatteringcoefficient,isimportantforsyntheticapertureradar(SAR)imagequalityassessment and SAR radiometric calibration, which, however, is difficult to realize in practicewithaknownbackscatteringcoefficient.Werealizeastrongbackscatteringhomogeneousregionwith a known backscattering coefficient in SAR images by utilizing designed metal grids. First,we propose a manmade grid-structure target and realize it with aluminum in practice, which isnamedthemetalgrid.Then,thebackscatteringcoefficientofthedesignedmetalgridissimulatedin the computer simulation technology (CST) microwave studio and measured by a radar cross-section (RCS) measurement instrument in a microwave anechoicchamber.Both CST simulationresults and RCS measurement results confirm the strong backscattering property of the designedtarget. In addition, by utilizing the designed target, we realize a test field consisting ofseveral strong backscattering homogeneous regions with different sizes at Shanghai JiaoTong University, Shanghai, China. The spaceborne experiments have been carried out by theTerraSAR-X sensor over the test field in two flight campaigns in X-band with VV polarization.Experimental results demonstrate the strong backscattering property and homogeneity of therealized regions.

Transmit Array Antenna Using Nonuniform Dielectric Layer

A shaped-beam Transmit Array Antenna based on nonuniform dielectric layer is proposed. Stepping the surface of dielectric layer provides the required phase shift at each point on the surface of transmit array antenna to produce a squared cosecant beam on the other side. In order to analyze this kind of antennas, a simple method based on an equivalent circuit model is introduced, in which the transmission coefficient of each element for oblique incident field is obtained. The design process consists of two steps. First, a phase-only technique is applied to obtain the required phase-shift distribution on the surface of transmit array antenna which generates the shaped pattern. The second stage consists of determining the thickness of each element to achieve the phase distribution obtained in the previous step. Using this method a shaped beam transmit array antenna in the 9.5-10.5 GHz band is designed, manufactured and also validated by the Computer Simulation Technology (CST) Microwave Studio TM package. The results of test in an anechoic chamber, shows a good agreement between measured, simulated and theoretical radiation patterns.

VIA HOLE - DUAL RECTANGULAR SLOTTED MICROSTRIP PATCH ANTENNA (MPA) DESIGN FOR RADIO ASTRONOMY, SATELLITE, CIVIL AND MILITARY APPLICATONS

In this paper, via hole drilled microstrip patch antenna employing two rectangular slots on patch, FR4 substrate having thickness of 1.6mm and dielectric constant of ɛr = 4.4 has been proposed. The proposed antenna has been designed and analysed using Computer Simulation Technology (CST) Microwave Studio 2014. The proposed antenna has compact size, light weight and wide band operation. The via hole slot and rectangular slots have been cut in the proposed antenna in order to increase the return loss and impedance bandwidth of the antenna. The proposed antenna ground and patch has been designed using copper of thickness 0.1mm. It has been analysed that the proposed antenna has an impedance bandwidth of 725MHz with an operating frequency range of 2.6787-3.4038GHz and is resonant at 2.905 GHz. The gain, directivity and return loss of the proposed antenna are 4.52dB,4.011dBi and -72.93dB at resonant frequency of 2.905GHz, respectively. The proposed antenna can be suitably employed for Aeronautical, Weather Radar applications (2700MHZ-2900MHz), Civil and Military applications (2900MHz-3100MHz) and Satellite applications (3100MHz-3300MHz.)

DESIGN OF LINEAR AND CIRCULAR POLARIZED ANTENNA FOR WLAN APPLICATION

In this paper, a linear and circular polarized antenna with operating frequency at 2.4 GHz for Wireless Local Area Network (WLAN) application is proposed. Firstly, a basic linear polarization antenna (Design A) was designed with rectangular slot at the rectangular patch and air gap between substrate and copper layer with distance of 10 mm. Next, in order to perform circular polarized, the antenna designed is added with optimized dual circular notch at the rectangular slot. This circular polarized antenna is designed with two different polarization types which are right-handed circular polarization (RHCP) with optimized dual circular notch at the patch (Design B) and left-handed circular polarization (LHCP) with optimized dual circular notch at the patch (Design C). The proposed antenna had been designed and simulated by using Computer Simulation Technology (CST) Microwave Studio Suite. The comparison result of simulation and measurement show that the proposed antenna can achieve axial ratio above 3 dB for linear polarized and below 3 dB for circular polarized with return loss less than -10 dB.

Analysis of Negative Refractive Index Asymmetric Chiral Metamaterial Based on L Shaped Structure

An asymmetrical chiral metamaterial at microwave frequency is constructed by using four double-layered L-shaped strips which are rotated by 900 with respect to their adjacent metal strip. These different size strips allows another degree of freedom in the equalizing the orthogonal components of the electric fields at the output interface with 90o phase difference when the x-polarized wave excites the structure. The proposed structure exhibits the properties of chiral medium such as optical activity and circular dichroism. The L shaped chiral objects can be etched on double side substrate. The effect of structure on different electromagnetic parameter like chirality, optical activity and reflection characteristics are analyzed. Due to the strong chirality the structure posses negative refractive index for either left circularly or right circularly polarized wave. In this paper, a numerical study in the frequency domain of the electromagnetic-wave propagation through these types of structures is achieved by using the commercial software Computer Simulation Technology (CST) microwave studio.

On the Use of Gaussian Random Processes for Probabilistic Interpolation of CubeSat Data in the Presence of Geolocation Error

With their greatly reduced sizes, low development cost, and rapid construction time, CubeSats have merged as a platform of considerable interest for a wide range of applications, including remote sensing. Many applications require the interpolation of sensor data into a regularly spaced grid for the development of downstream scientific products. This problem is complicated for CubeSat platforms due to potentially significant uncertainties associated with the spatial position of the satellite. In this paper, we present a probabilistic approach to the data interpolation problem in which we estimate both the platform location and data samples on a regular grid given observations corrupted by noise and location error. Our approach is based on a Gaussian process model to connect the measured data to the values on the grid. Two statistical models for positional uncertainties are considered, one based on an assumption of independent errors and another motivated by positional errors associated with a specific platform of interest, the MicroMAS radiometer. In each case, the maximum a posteriori estimate of the positions and the data is generated using an optimized Gaussian process regression (OGPR) method resulting in two algorithms: OGPR-IID and OGPR-PCA. The performance of this approach is tested on both simulated data and advanced technology microwave sounder data where significant improvements both qualitatively and quantitatively relative to traditional interpolation methods are observed.

Analysis of Double Layer Cross Strips with Chiral Configuration Exhibiting Negative Refractive Index

Metamaterials composed of metallic strips on both side of the substrate are analyzed at microwave frequencies. The rectangular shaped metallic foils are rotated by 90o with respect to their adjacent metal strip on each side of the substrate. The twist angle between the cross strips on opposite sides of substrate is 40o. The proposed structure exhibits the properties of chiral medium such as optical activity and circular dichroism due to their cross coupling between the electric and magnetic fields. The rectangular shaped chiral objects can be easily fabricated on double side substrate. Both transmission and reflection resonances are illustrated. The chiral configuration of this metamaterial structure is analyzed in commercial software Computer Simulation Technology (CST) microwave studio and negative refractive index is observed. Moreover, other electromagnetic structural parameters such as chirality, optical activity and polarization effect are discussed.

Design and Investigation of H-Shaped Patch Antenna Integrated with Light Emitting Diodes

The limitations in the applications of microstrip antenna lead to wastage in the form of space and functionality. In order to overcome the wastage of space and functionality of the microstrip antenna, the new idea is to make one single device of microstrip antenna which has two application at the same time where it can operates as antenna and the function as lighting source is proposed. Light Emitting Diode (LED) has been chosen as the light source since the characteristic and the structure of the LED are suitable for the integration process. Hence, this paper presents an investigation on the characteristic of an H-shaped patch antenna integrated with Light Emitting Diodes (LEDs).The proposed integrated antenna has been designed and simulated by using Computer Simulation Technology (CST) Microwave Studio Software. It has been fabricated and measured to investigate the performance of the antenna in terms of return loss. The results confirms that the antenna can operate at 2.4 GHz and it works well as an illumination.