CST Results Research Articles

Random forest regression for radiation pattern prediction of planar metasurface reflector antenna

This letter presents a novel random forest regression (RFR) based machine learning (ML) method for predicting the radiation properties of a planar metasurface reflector (PMSR) antenna. The extracted parameters of PMSR at 2.45 GHz serve as input for the RFR model for training on power flows and radiation properties. For comparison, an experiment with PMSR fed by the patch at d=0.6λ0 is performed to estimate the difference in the RFR and CST. The observed findings match the CST and RFR results, with minimal discrepancies in the E- and H-plane. This novel approach is valuable for determining antenna radiation properties in non-line-of-sight or misaligned receiver situations, providing a baseline study and design guide for lightweight, planar mobile reception reflector antennae.

Analysis of dielectric resonator antenna using natural fiber reinforced polymer composites

This work aims to demonstrate the viability of replacing natural fiber reinforced polymer composites for hard ceramics in millimeter-wave dielectric resonator antennas (DRA). The dielectric characteristics of three novel natural fiber reinforced polymer composites were determined using the Lichtenecker logarithmic mixing law. Using two commercial antenna design software packages, CST Studio and ANSYS HFSS, the resulting dielectric characteristics were utilized to study a probe-fed rectangular DRA. Natural fiber-reinforced polymer-based DRAs offer a wider bandwidth than ceramic-based DRAs. Close coupling is obtained by the three natural fiber-reinforced polymer-based antennas and the ceramic DRA. In all cases, the impedance bandwidths observed are the consequence of quasi-TM111 mode radiation. HFSS studies indicate that the resonance frequency of the natural fiber reinforced polymer based DRAs is roughly 75 percent higher than that of the ceramic DRA. CST results indicate that the resonance frequency of the natural fiber polymer-based DRA is approximately 88 percent higher than that of the ceramic DRA. Natural fiber reinforced Polymer-based DRAs have three times the −10 dB impedance bandwidth of ceramic-based DRAs.

470. Changing Urgent Care Patterns of Diagnosing Coccidioidomycosis in a Highly Endemic Urban Population

Abstract Background We found previously (Pu et al. Clin Infect Dis, 2021: PubMed 32511677) that only 0.2% of ICD10 codes for coccidioidomycosis (CM) in our health care system were associated with patients (pts) managed at an urgent care (UC) visit. Since 2020, during onboarding, at quarterly meetings, and in periodic emails, UC clinicians were encouraged to test for CM in patients with pneumonia (PNA). Methods For 2018 through 2021, Banner Health UC System increased clinics from 41 to 48, clinicians from 89 to 193 (Nurse Practioners, 49.2% ± 2%, Physician Assistants, 39% ± 2%, MDs/DOs 13% ± 1%), and total visits from 787 to 1,290 thousand. Average visits were 1.6 per pt. All UCs used a common electronic medical record (Cerner) during the study period. Data were downloaded in January 2022 to analyze UC clinician patterns of coccidioidal serologic testing (CST, 98% were EIAs), CST results, and their relation to ICD10 codes. Results For the study period, CST orders increased from 8.0 to 19.0 per 10,000 UC visits (chi-squared p< 0.001). The percent of clinics testing >10 per year increased from 16% to 78%, and the percentage of clinicians testing increased from 37% to 67%. Percent positive CSTs were highest for August, November, and December (27.4%) and lowest from April through July (8.1%). PNA ICD10 codes (J18.9 or J18.1) were most frequently associated with positive CSTs (374 positive of 1,872 tested), and the ICD10 code for Erythema nodosum (EN, L52, 176 total pts) had the highest positivity rate (61.4%, 27 positive of 44 tested). Only 6 pts had both EN and PNA codes. As indicated in the table, testing of PNA pts over time increased on first visits, decreased on second visits, and increased on second visits when the first CST was negative. Testing also increased for EN pats. Despite these favorable changes, CST was still not done on over three quarters of pts where recommended. Coccidioidal serologic testing in urgent care clinics by month for 2018-2021. Open circles are percentage of total visits that involved a test; closed squares are percentage of tests that are positive. Conclusion Routine quality improvement activities have significantly but only partially improved rates of testing pts with PNA or EN for CM in UC clinics located in an endemic area. Innovative strategies to change clinical practices may be needed to achieve greater success. Disclosures All Authors: No reported disclosures.

Reflection and transmission properties of a graphene-dielectric-thin resistive layer structure in the THz range

We studied two-dimensional planar dielectric slab, sandwiched by graphene and thin resistive layer from two sides. Problem geometry is illuminated by a H-polarized electromagnetic plane wave from upper side. It is expected to observe the reflection and transmission performance of such a composite slab geometry depending on the electrical and geometrical parameters. We used the local reflection and transmission coefficients method to determine the overall performance. It is seen that the proper selection of the electrical resistivity of the thin resistive layer reduces the reflection from lower boundary of slab and the electrical thickness becomes less important for high THz range. Then, the geometry turns to be an air-dielectric interface. This is a novel finding and completely different from the pure dielectric slab without coatings which has frequency dependent characteristics. Also higher reflections are observed due to the higher conductivity of graphene in the low THz range. Furthermore, a sample finite plate is constructed in a same manner and it is modeled by using CST software. Presented method using equivalent 2D profile model and CST results are compared and very good consistency is observed. In both cases, the reflection can be controlled with the chemical potential at low THz range and the selection of the relative permittivity of the dielectric material determines the reflectance level at higher THz scale. We demonstrate these statements in the numerical results section for various problem parameters and angle of incidence.

Compact high gain 28, 38 GHz antenna for 5G communication

ABSTRACT In this research paper, a miniaturized vertically polarized dual band antenna with its 2x2 MIMO configuration is proposed for 5G communication. The single antenna consists of an off-centered fed, concave-shaped patch surrounded by two mirror-image C-shaped strips. It works as a millimeter wave radiator for 28/38 GHz bands which provide the transmission at ultra-high speed with a gain of 7.46 dBi and 8.56 dBi and an efficiency of 77% and 91% at both frequency bands respectively. The antenna offers a small-scale size of 10 x 10 x 0.254 mm3 and the close compatibility of simulated and measured results shows the practical feasibility of the fabricated prototype for 5G handheld devices. It can be used for device to device communication at 28 GHz and 38 GHz can be used for 5G cellular communications with higher speed, connectivity and low latency. Apart from that an electrical equivalent circuit of the antenna based on its physical structure is designed using AWR software and its results are included and compared with the CST results. The low specific absorption value of 1.05/0.288W/kg at 28/38GHz and the appropriate results of various parameters for MIMO design confirm its relevance for the 5G MIMO applications.

Multi-layered swastika shape antenna patch design for GSM and WiMAX applications

The key design issues of an antenna for wireless communication are wide bandwidth, high gain, and balanced directivity. In order to satisfy the above needs for the bandwidth enhancement the electro geometrical modelling of antennas is highly necessary. In this paper, the design and simulation of the Multi-layered Swastika patch antenna, with different substrates for the enhancement of bandwidth and various other parameters, have been analysed using CST and simulated results are tabulated. The proposed antenna has multiple consecutive layers over each other operating at a frequency 2.45 GHz and the simulation results are suitable for using in GSM and WiMAX applications.

A Compact Wideband Dielectric Loaded H-plane Sectoral Ridged SIW Horn Antenna

In this paper a compact and wideband ridged substrate integrated waveguide (RSIW) horn antenna is proposed. Unlike the previous works, the ridge structure in the proposed antenna is tapered only along the width allowing the antenna to be designed on just two-layer dielectric substrate. The tapered ridge is created by simple, different diameter size vias just in one layer. The antenna designed has dimension of 14 × 33 × 3 mm3 (1.4λo × 3.3λo × 0.3λo, where λo is the free space wavelength at 30 GHz) and a has a bandwidth of 41.32% covering 24 - 36.5 GHz with the reflection coefficient, S11, under -10 dB. The antenna is simulated through two software packages CST and HFSS and results are compared.

Miniature Slotted Semi-Circular Dual-Band Antenna for WiMAX and WLAN Applications

In this paper, a new approach is presented for designing a miniaturized microstrip patch antenna (MPA) for dual-band applications. The proposed MPA consists of a semi-circular patch radiator fed by a 50-Ω coplanar waveguide (CPW) structure with a tapered-ground plane for enhancing impedance bandwidth over the dual-band. By inserting a folded U-shaped slot into the semi-circular patch, the proposed antenna introduces an additional higher-order mode but does not modify the resonance frequency of the lower-order mode of the patch, yielding the desired dual-band response. For antenna miniaturization, the circular-shaped radiator of the reference antenna (RA) was converted into a semi-circular radiating patch. Agreement between CST and HFSS simulated results led us to manufacture a prototype of the designed antenna on one side of an inexpensive FR-4 substrate with an overall dimension of 17 × 18 × 0.8 mm<sup>3</sup>. The measured result in terms of reflection coefficient S11 confirms that the antenna operates in both 3.5 GHz (3.4–3.7 GHz) and 5.8 GHz (5.725–5.875 GHz) bands suitable for use in WiMAX and WLAN applications, respectively. Moreover, besides an area reduction of 32% compared with the RA counterpart, the proposed antenna has other features, a simple geometry, and is easy to manufacture in comparison with previously reported antenna structures.

A tri-band left-handed meta-atom enabled designed with high effective medium ratio for microwave based applications

This paper represents a tri-band left-handed meta-atom with high effective medium ratio, which is applicable for tri-band microwave based communication applications. The proposed meta-atom consists of modified complementary split ring resonator (CSRR) with two pi shaped metal strip loaded in the inner side. It shows the behavior of negative permeability and permittivity at 2.85 GHz, 4.83 GHz, 8.39 GHz, and 11.42 GHz resonance frequencies and extracted the double negative (DNG) metamaterial properties. The designed meta-atom dimension is 0.076λ×0.076λ at lower resonance frequency. To develop and analyze the offered meta-atom, the electromagnetic (EM) simulator CST Microwave Studio and MATLAB software were used. The equivalent circuit with RLC components of the proposed metamaterial unit cell is also investigated through ADS simulator and comparing S parameter (transmission coefficients) results with CST results. Analysis and comparison have been carried out with different configurations, such as various design structures, distinct substrate, changing the gap of the splits, and various array measures. All the array configurations proved that the frequency of operation is in the S-, C-, and X-bands. The designed meta-atom has double negative regions of 2.89–2.96 GHz, 4.84–4.99 GHz, 8.42–8.49 GHz, and 11.43–12.32 GHz, with the regions of effective negative refractive index 2.85–3.09 GHz, 4.83–5.36 GHz, 8.40–8.57 GHz, and 11.40–12.55 GHz, respectively. The effective medium ratio is 13.16; this implies that the proposed miniaturized meta-atom design is efficient and compact. The scattering parameter dimension of the meta-atom promising for the microwave based applications at S-, C-, and X-bands.

Coccidioides (spherulin) skin testing in patients with pulmonary coccidioidomycosis in an endemic region†.

Coccidioidomycosis is an endemic fungal infection of the desert southwestern United States. Intact cellular immunity is critical to the control of this infection. A recently released reformulated spherulin antigen (Spherusol; Nielsen BioSciences, Inc.) was approved to detect delayed-type hypersensitivity, which implies the presence of cellular immunity, to Coccidioides species. We aimed to summarize our experience with this test in patients with primary pulmonary coccidioidomycosis. We retrospectively reviewed clinical data for all patients with primary pulmonary coccidioidomycosis who had a Coccidioides (spherulin) skin test (CST) placed at our institution between January 1, 2015, and August 31, 2017. During the study period, 172 patients had a CST placed, and 122 met our inclusion criteria for proven or probable pulmonary coccidioidomycosis. Of these 122, 88 (72.1%) had a positive CST result and 34 (27.9%) had a negative result. In the positive CST group, 74 of the 79 treated patients (93.7%) had antifungal treatment stopped, 1 of whom (1.4%) had relapsed infection. In contrast, 27 of the 33 treated patients in the negative CST group (81.8%) had their antifungal treatment stopped, and none had a relapse. Seven patients overall (5.7%), all of whom had a positive CST, experienced mild local adverse reactions to the CST. Although previous controlled studies of CST showed sensitivity and specificity greater than 98%, our real-world experience with the CST showed lower rates of positivity. Negative CST results did not predict relapse with antifungal agent withdrawal.

Design and Investigation of Dual Band CDRA Excited by Conformal Feed for Broadband Wireless Applications

In this paper dual band Cylindrical Dielectric Resonator Antenna (CDRA) excited by conformal trapezoidal patch is successfully developed and investigated for broadband wireless applications. Rogers TMM10i (dielectric) is used for fabrication of CDRA, which have 9.8 dielectric constant (Ɛr). A 50 Ω microstrip line integrated with vertical trapezoidal flared patch is used to feed the antenna. The measured result offers wide VSWR bandwidth matching in two bands from 2.25 to 4 GHz and 4.7 to 5.7 GHz for |S11| < − 10 dB. The average peak gain is more than 3.1 dBi for a first operating band with gain flatness less than ± 2 dB and 8.3 dBi for the second operating band with gain flatness less than ± 1.5 dB. The proposed antenna covers the entire important wireless communication band i.e. Wi-Bro (2.3–2.4 GHz), Bluetooth (2.4–2.484 GHz), WLAN (2.4–2.485 GHz and 5.15–5.7 GHz), Wi-MAX (2.5–2.7 GHz and 3.4–3.6 GHz), Satellite DMB (2.605–2.655 GHz) and LTE (3.2–3.3 GHz). A comparative analysis of antenna’s parameters has been examined by CST Microwave Studio and results are verified through experimental outcomes.

Change of terahertz antenna spectrum when surrounding dielectric alters

The spectrum of terahertz antenna was studied when the dielectric’s covering dielectric as was changed in type, thickness or distance to electrodes. The surface wave theory was used to explain the physics of current pulse propagation in antenna electrodes, showing that the covering dielectric affected the propagation velocity of the current pulse on electrodes. Here, the emission spectrum of a dipole THz antenna on LTG GaAs was simulated via CST software. It was detected that the amount of thickness, permittivity and position of the covering dielectric influenced the spectrum of emitted THz as well electrode thickness. On the other way the capacitance equivalent of the antenna is calculated via COMSOL MultiPhysics software and it is detected the covering dielectric can affect capacitance and then resonance frequency antenna which is consistent with our CST results.

Using acrylamide/propylene oxide copolymers to dewater and densify mature fine tailings

Adding hydrophobic groups to polyacrylamide (PAM) flocculants improves flocculation and dewatering (settling, turbidity, capillary suction time and solids content after centrifugation) of mature fine tailings (MFT). In this study, we copolymerized different amounts of polypropylene oxide macromonomers (PPO) with acrylamide to produce PAM-PPO graft copolymers with different hydrophobicities and molecular weights. According to CST, turbidity and centrifugation results, the PAM-PPO copolymers dewatered and densified MFT more efficiently than a reference commercial anionic PAM supposedly because the PPO hydrophobic groups reduced the amount of water trapped inside the polymer floccules. Besides densifying and dewatering tailings more efficiently, the PAM-PPO copolymers had molecular weights ten times smaller than the reference anionic PAM flocculant, which reduced their viscosities and shear-sensitivities. As a result, it is easier to mix these copolymers with tailings under a wider window of operating conditions. We also observed that aged MFT (stored for approximately 10months) were more easily dewatered, especially at high solids content (20wt%). This behavior might be attributed to the evaporation of water, hydrocarbons, or other low molecular weight organic compounds. However, further studies are required to understand what and how chemical compositional changes alter the stability of MFT. The information generated in these studies could be used to design polymers that could target the MFT components responsible for its high stability and slow consolidation.

A new C and Ku-band logarithmically periodic linear bowtie antennas array design using lumped-element equivalent schematic model

In this paper, a new C and Ku-band antennas arrays design using lumped-element equivalent schematic technique which can cover respectively the band from 3.7 to 4.2GHz devoted to downlink C-band applications and from 10.7 to 12GHz are fabricated and measured. The design is based on an optimization process taking into account an implementation of lumped-element equivalent schematic in ADS of Agilent software in order to conceive logarithmically periodic linear bowtie antennas array. The basic bowtie simple schematic consists of two identical tapers used directly from the transmission line model to compute the input impedance matching at any frequency providing the resonance. The obtained results show the effectiveness of this method to analyze such types of antennas. The measured and simulation given by CST and Momentum software's results proves the effectiveness of the proposed lumped-element equivalent schematic. The results show that bandwidths from 3.7 to 4.14GHz and from 10.78 to 12.01GHz are obtained which can be used for C-band downlink and Ku-band applications.

Effect of unit-cells of the frequency selective surface as superstrate on the directivity of rectangular microstrip antenna

In this paper, the relationship between the number of unit-cells used in the design of a frequency selective surface (FSS) and its expected directivity is established. The relationship between the number of FSS unit-cells and the directivity is based on the planer microstrip patch array antenna design concept where the unit-cell is treated as the superstrate illuminated by the source. To validate the proposed technique, the analytical value of the directivity has been compared with that of ray-tracing method. The directivity of antenna is calculated for two different planar array configurations at 600 GHz. The results of numerical analysis are compared to that of the full-wave electromagnetic simulator CST Microwave Studio and results are comparable. Further, the directivity computed by this proposed technique has also been compared with that of the reported in literatures.

Ozone oxidation of biological sludge: Effects on disintegration, anaerobic biodegradability, and filterability

AbstractThis study deals with pretreatment of biological sludge by ozone oxidation for the purpose of biological sludge disintegration. Different ozone dose ranged between 0.005 and 0.25 gO3/g DS were used for the process optimization. The potential for improving anaerobic digestion through ozone oxidation was also investigated. In addition, the effect of ozone oxidation on filterability characteristics of sludge was evaluated using lab‐scale experiments. The results showed that ozone effectively disintegrates the sludge. The highest disintegration degree (51.1%) was achieved when 0.1gO3/g DS was used. Biochemical methane potential (BMP) results suggest that ozone oxidation significantly enhanced the biodegradability of biological sludge. For 0.1 gO3/g DS, 25% higher methane production was achieved compared with raw sludge. The supernatant characteristics of the sludge were also affected by ozone oxidation. For 0.1 gO3/g DS, the soluble chemical oxygen demand (SCOD), dissolved organic carbon (DOC), total nitrogen (TN), and total phosphorus (TP) increased by 300%, 94.2%, 225%, and 200%, respectively. Finally, using ozone oxidation for the purpose of floc disintegration (0.1 gO3/g DS) had no negative effect on sludge filterability in terms of CST results. But at higher doses than 0.1 gO3/g DS, ozone oxidation reduced the filterability of sludge. © 2010 American Institute of Chemical Engineers Environ Prog, 2011

Filter design and mode suppression inside metamaterial-filled rectangular waveguides

Filter characteristics and mode suppression capabilities inside metamaterial- (MTM) filled rectangular waveguides are investigated. Frequency characteristics of single-negative (SNG) and double-negative (DNG) finite slength transverse slabs inside rectangular waveguides are numerically simulated. The simulations are performed via in-house-prepared three-dimensional (3D) finite-difference time-domain package; MTM-3D. Simulations are also repeated with the commercial CST Microwave Studio package and results are compared. Tests show that different combinations of SNG and DNG slabs located transversely inside a rectangular waveguide can be used to obtain multi-stopband filters and to suppress modes (i.e., resonances). © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1659–1663, 2010; Published online in Wiley InterScience (www.interscience. wiley.com). DOI 10.1002/mop.25289

Shear sensitivity of digested sludge: Comparison of methods and application in conditioning and dewatering

Shear sensitivity of digested sludge was evaluated by two methods: a CST shear test and a strain sweep rheological method of measuring yield stress. Sludge pretreatment by an enzyme formulation was used to alter the sludge's response to shear and, potentially, to improve dewaterability. Also varied were the polymer conditioning dose and the amount of shear applied by mixing. A bench-scale device was then used to simulate dewatering by belt press in order to assess the CST shear tests and the rheological test. CST-based shear tests showed that the optimum chemical conditioner doses with low shear levels became sub-optimal with increasing mixing times. For all three polymer conditioners, longer shear times increased the dose requirements. When the polymer dose was held constant, and the extent of mixing varied, the CST test was a poor indicator of effects on dewaterability. The benefits of enzyme treatment, apparent by actual dewatering, were not predicted by the CST results. In contrast, yield stress values were significantly correlated with cake solids values, and inversely correlated with filtrate solids. Yield stress is not adequate by itself to predict final cake solids after dewatering, because enzyme pretreatment gave higher solids concentrations when both shear extent and initial yield stress were held constant.