A Novel Dielectric-Loaded Dual-Mode Cavity for Cellular Base Station Applications

A new class of dual mode dielectric resonator filter for mobile communication systems is presented. The proposed resonator exhibits high unloaded quality factor and reasonably wide spurious operating window. Based on this cavity, a 4-pole dual-mode Generalised Chebyshev filter is developed and fabricated in the stacked configuration. An unexpected spurious mode is appeared at 2.3 GHz due to improper coupling. A coupling technique for eliminating the unexpected spurious resonance is proposed. The obtained experimental and measured results with an asymmetric transmission zeros confirm the validity of the proposed resonator for releasing filters for cellular-radio base stations

A TE11 Dual-Mode Monoblock Dielectric Resonator Filter

A novel TE11 monoblock dual-mode dielectric resonator filter is presented in this paper. The proposed filter is made of a single piece of ceramic with silver plated external surfaces and metallic lids for hosting tuning elements. The dominant TE11 dual-mode is supported by H-shape dielectric resonator having r =45. The resonator is ultra-compact in size and offers a maximized space utilization since no metallic housing is required. In addition, the proposed resonator offers a high unloaded quality factor, reasonably wide spurious window and lend itself to implement tunability. One prototype filter operating at 1.96 GHz with 50-MHz bandwidth is designed

Compact Triple-Mode Microwave Dielectric Resonator Filters

This paper presents a novel and compact triple-mode dielectric resonator (DR) band- pass filter (BPF) based on a single waveguide cavity. A triple-mode resonator can be achieved by pairing the degenerate EH₁₁ modes with a TM01δ mode. The DR structure is composed of two slitted pieces of dielectric pucks that are placed in the middle of a cylindrical metallic cavity. The resonator offers a size reduction ratio of about 15.6% compared with equivalent air-filled coaxial filters. A coaxial probe is used to excite the degenerate EH₁₁ modes while the TM01 mode is excited using a vertical hole etched in the ceramic pucks. Finally, a 3rd order generalised Chebyshev BPF is simulated using HFSS software. The filter has finite transmission zeros(TZ) on the high or low side of the passband

Design and Characterisation of HE11 Dual-Mode Dielectric-Loaded Filter for Cellular Base Station Applications

This paper presents a HE11 dual-mode dielectric-loaded bandpass filter for cellular base station applications. The filter consists of a ceramic puck that is placed centrally on the base of a metallic housing. The resonator offers a size reduction ratio of approximately 7:1 compared with equivalent air-filled coaxial filters. The filter is designed at a resonant frequency of 2.05 GHz and bandwidth of 50 MHz. The spurious-free window (SFW) was 500 MHz from the fundamental frequency. A fourth order dual-mode bandpass filter is designed, fabricated, and tested to validate the proposed approach. A good agreement between the measurement and simulation results is demonstrated

Lower Extremity Joint Stiffness During Running in Adolescents with Autism Spectrum Disorder

During late adolescence, children undergo rapid skeletal growth changes leaving the child more vulnerable to injury during physical activity. This is consistent for autistic youth, who reportedly enjoy individual activities, such as running, more than team-based sports [1-3]. Inadequate joint stiffness is one of several factors that may influence injury risk [4]. The purpose of this study was to examine lower extremity joint stiffness in autistic and non-autistic matched controls at self-selected and matched running speeds. Twenty-two persons with a confirmed autism spectrum disorder (ASD) diagnosis and seventeen age, sex, and body mass index controls (CON) were enrolled into the study. Position and force data were collected in the Neuromechanics Laboratory using the motion capture system. Participants were asked to complete a series of over-ground running trials at their self-selected speed and a standardized speed of 3.0 m/s. Joint stiffness was calculated as the quotient of the change in joint moment and the change in joint angle during the energy absorption period of stance. Statistical analyses were performed in SPSS (version 27, IBM Corp.). Stiffness and changes in joint moments were analyzed using 2 (group) x 2 (speed) analyses of variance. There were no significant interactions between groups and speeds (p\u3e0.05) for any variable. Persons with ASD had reduced knee and ankle joint stiffness (all p Persons with ASD had reduced lower extremity stiffness, which was due to their reduced joint moments. Decreased joint stiffness by those with ASD could be indicative of a less efficient running style whereby the elastic recoil is not being optimally utilized.https://digitalcommons.odu.edu/gradposters2022_education/1006/thumbnail.jp

Miniature Triple-Mode Dielectric Resonator Filters

In this paper, a new class of triple-mode microwave filters is presented. These devices use the degenerate pair of the HE11δ mode and the single TM01δ mode in dielectric-loaded cavities with an unloaded Q-factor of 3000-5000 and reasonable spurious-free window. The proposed structure is obtainable in less than one-quarter of the physical volume of equivalent TEM filters. A finite-element method solver for electromagnetic structures (HFSS) is used to study the main properties of this resonator. Fundamental design rules for triple-mode bandpass filters with controllable finite transmission zeros are presented. Design examples of bandpass filters with finite transmission zeros on the high or low or both sides of the passband are demonstrated. Measured results demonstrate excellent performance

Broadband Dual-Mode Dielectric Resonator Filters

This paper presents a broadband dual-mode microwave filter suitable for mobile communications. The Conductor loaded dielectric resonator filter reported in [5] is used as the basic building block for these devices. A simple input coupling configuration is introduced to improve the filter bandwidth significantly with less than half of the physical volume of TEM filters and good electrical performance. The basic properties of this resonator have been studied using a finite element method electromagnetic software (HFSS). Fundamental design rules for broadband bandpass filters have been presented. A two-pole bandpass filter was designed, fabricated and measured to verify the proposed approach

A fixed-target platform for serial femtosecond crystallography in a hydrated environment.

For serial femtosecond crystallography at X-ray free-electron lasers, which entails collection of single-pulse diffraction patterns from a constantly refreshed supply of microcrystalline sample, delivery of the sample into the X-ray beam path while maintaining low background remains a technical challenge for some experiments, especially where this methodology is applied to relatively low-ordered samples or those difficult to purify and crystallize in large quantities. This work demonstrates a scheme to encapsulate biological samples using polymer thin films and graphene to maintain sample hydration in vacuum conditions. The encapsulated sample is delivered into the X-ray beam on fixed targets for rapid scanning using the Roadrunner fixed-target system towards a long-term goal of low-background measurements on weakly diffracting samples. As a proof of principle, we used microcrystals of the 24 kDa rapid encystment protein (REP24) to provide a benchmark for polymer/graphene sandwich performance. The REP24 microcrystal unit cell obtained from our sandwiched in-vacuum sample was consistent with previously established unit-cell parameters and with those measured by us without encapsulation in humidified helium, indicating that the platform is robust against evaporative losses. While significant scattering from water was observed because of the sample-deposition method, the polymer/graphene sandwich itself was shown to contribute minimally to background scattering

Assessing the sustainability reporting of selected tourism companies listed on the Johannesburg Stock Exchange (JSE)

Abstract Implementing corporate sustainability reporting as part of companies' annual reports is a requirement in South Africa and throughout the world. The King III code strongly encourages Johannesburg Stock Exchange (JSE) listed companies to integrate their environmental, social and economic practices into their annual reporting. The purpose of this study was to investigate the sustainability reporting practices of three selected tourism companies listed on the JSE namely: Sun International, City Lodge and Wilderness Holdings. Three evaluation frameworks were developed from 1) the Global Reporting Initiative (GRI: G3.1); 2) the JSE: Social Responsible Investment (SRI) Index criteria; and 3) the South African National Standard for Responsible Tourism (SANS 1162) criteria. The three evaluation frameworks were used as a tool to assess the tourism companies' annual reports. Using these frameworks provided a way of assessing the extent of sustainability reporting within annual reports and allowed for comparison across companies and years. Overall, the study provided an understanding of how the selected companies had been producing their annual reports from 2010 to 2012. The study also provided feedback on the companies' previous reporting practices in terms of the sustainability criteria and provided information on how these companies can improve their future sustainability reporting