scholarly journals A Second-Iteration Square Koch Fractal Slot Antenna for UHF Downlink Telemetry Applications in CubeSat Small Satellites

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Jorge Simon ◽  
Jorge Flores-Troncoso ◽  
Jose Luis Alvarez-Flores ◽  
Leonel Soriano-Equigua ◽  
Marco Cardenas-Juarez ◽  
...  
Keyword(s):  
Reflection Coefficient ◽  
Fractal Geometry ◽  
Low Cost ◽  
Economic Cost ◽  
Slot Antenna ◽  
Limited Area ◽  
Cost Difference ◽  
Small Satellites ◽  
Koch Fractal ◽  
Uhf Band

This article presents the design, fabrication, and measurement of a square Koch fractal slot antenna for UHF band using both the FR4-G10 and Cuclad 250 substrates. Conveniently, this 56.56 cm full-length antenna possesses a geometry that allows it to be incorporated into the standardized 10 cm × 10 cm faces of the CubeSats. Furthermore, it is shown that both selected substrates exhibit an acceptable performance at the frequency of interest despite the economic cost difference and relative permittivity. Hence, the commercial FR4-G10 antenna substrate can be preferred because of its low-cost and admissible performance at 458 MHz, which is a frequency in the UHF band that is commonly used for telemetry, tracking, and command downlinks of CubeSats. Measurements show that the proposed antenna exhibits a reflection coefficient of −16.53 dB, a bandwidth of 22.62 MHz at −10 dB, a VSWR of 1.3508, a normalized impedance of 0.794 − j0.173 at 50 Ω, and a directivity of 2.24 dBi. The contribution of this work consists in the use of a fractal geometry to construct a low-cost slot antenna working at UHF frequencies over the limited area of the CubeSat faces and in order to optimize the area for an eventual coexistence with solar cells.

Selectivity and in-band impedance enhancement of a compact slot antenna with defected ground structures

2019 ◽  
Vol 11 (10) ◽  
pp. 1010-1016
Author(s):  
Hailong Yang ◽  
Xiaoli Xi ◽  
Lili Wang ◽  
Yuchen Zhao ◽  
Xiaomin Shi
Keyword(s):  
Reflection Coefficient ◽  
Impedance Matching ◽  
Ultra Wideband ◽  
Band Edge ◽  
Slot Antenna ◽  
Defected Ground Structure ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Uwb Antennas ◽  
Low Pass

AbstractIn this study, a new ultra-wideband (UWB) band-edge selectivity antenna with a modified radiation slot using defected ground structure (DGS) is presented to obtain bandpass filtering reflection coefficient and gain performance. The well-designed DGS is designed on backside metallic of the substrate and can be seen as a low-pass filter that provides a good roll-off at a higher frequency. By connecting the DGS and the stepped slot and making them merge with each other, good cut-off property in the upper passband and better in-band impedance characteristics are obtained. Measured results show that the proposed design not only shows good band-edge selectivity in reflection coefficient and gain performance but also has a good impedance matching of −13.5 dB reflection coefficients and a good radiation efficiency of 90% in the operating frequencies. The measured bandwidth defined with the reflection coefficient less than −10 dB is from 3.1–11.2 GHz. Furthermore, the size of the filtering UWB antenna is 22 mm × 12 mm, which is smaller than many individual UWB antennas and UWB filters.

Seismic Performance of RC Short Columns Strengthened with BFRP

2013 ◽  
Vol 351-352 ◽  
pp. 1532-1536 ◽  
Author(s):  
Bin Ding ◽  
Li Jun Ouyang ◽  
Zhou Dao Lu ◽  
Wei Zhen Chen
Keyword(s):  
Seismic Performance ◽  
Failure Modes ◽  
Low Cost ◽  
Economic Cost ◽  
Shear Capacity ◽  
Good Prospect ◽  
Loading Test ◽  
Fiber Reinforced Plastic ◽  
Short Columns ◽  
Reinforced Plastic

BFRP has excellent strength, durability, thermal properties and economic cost. To test seismic performance of short columns strengthened with BFRP. Low cyclic loading test was conducted on one comparative short column and two RC short columns strengthened with BFRP. The test shows that short columns warped by BFRP show excellent failure modes, shear capacity, ductility and energy dissipation. As a new fiber reinforced plastic, BFRP has a good prospect in the area of seismic strengthening for its low cost and comprehensive mechanical properties.

A Multimodule Planar Air Bearing Testbed for CubeSat-Scale Spacecraft

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
William R. Wilson ◽  
Laura L. Jones ◽  
Mason A. Peck
Keyword(s):  
Multibody Dynamics ◽  
Technology Development ◽  
Low Cost ◽  
Air Bearing ◽  
Cost Performance ◽  
Small Satellites ◽  
Ground Testing ◽  
Spacecraft Mission ◽  
Cost Scaling ◽  
Design Cost

In the past several years, small satellites have taken on an increasingly important role as affordable technology demonstrators and are now being viewed as viable low-cost platforms for traditional spacecraft mission objectives. As such, the CubeSat standard (1 kg in a 10 cm cube) has been widely adopted for university-led development efforts even as it is embraced by traditional spacecraft developers, such as NASA. As CubeSats begin to take on roles traditionally filled by much larger spacecraft, the infrastructure for dynamics and controls testing must also transition to accommodate the different size and cost scaling associated with CubeSats. While air-bearing-based testbeds are commonly used to enable a variety of traditional ground testing and development for spacecraft, few existing designs are suitable for development of CubeSat-scale technologies, particularly involving multibody dynamics. This work describes Cornell University's FloatCube testbed, which provides a planar reduced-friction environment for multibody dynamics and controls technology development for spacecraft less than 6 kg and a 15 cm cube. The multimodule testbed consists of four free-floating air-bearing platforms with on-board gas supplies that allow the platforms to float over a glass surface without external attachments. Each of these platforms, or FloatCubes, can host CubeSat-sized payloads at widely ranging levels of development, from prototype components to full-scale systems. The FloatCube testbed has already hosted several successful experiments, proving its ability to provide an affordable reduced-friction environment to CubeSat-scale projects. This paper provides information on the system design, cost, performance, operating procedures, and applications of this unique, and increasingly relevant, testbed.

scholarly journals Analysis of the Fee-to-Tax Reform on Water Resources in China

2021 ◽  
Vol 9 ◽  
Author(s):  
Zi-Rui Chen ◽  
Yuan Yuan ◽  
Xu Xiao
Keyword(s):  
Water Resources ◽  
Water Resource ◽  
Water Consumption ◽  
Tax Reform ◽  
Low Cost ◽  
Production Capacity ◽  
Cost Difference ◽  
Tax Rate ◽  
Leading Position ◽  
The Cost

The Resource Tax Law was officially implemented on September 1, 2020, in China. This law presents the “Fee-to-Tax” reform of water resources. This article compares the effects of the “Fee-to-Tax” reform under asymmetric duopoly conditions with perfect information. The mechanisms of the two policies are different when all firms simultaneously respond to water resources: the water resource fee affects output by reducing market size, while the water resource tax reduces output by amplifying the weighted cost difference effects between companies. Water resource taxes work better than fees for eliminating backward production capacity. A comparison of the situation when companies respond sequentially is also carried out. When a low-cost firm is in the leading position, the collection of fees actually reduces the output difference, whereas the tax improves it. When a high-cost firm acts as a leader, the effects depend on the cost difference. When the cost difference between firms is small, the first-move advantage of high-cost firms dominates the cost advantages of low-cost firms. Therefore, a higher tax rate yields a smaller output difference. When cost differences are relatively larger, the cost advantage of low-cost firms dominates the first-move advantage of high-cost firms. As the operational cost for reducing water consumption increases, the reduced water consumption first increases and then decreases.

scholarly journals Analysis of the Fee-to-Tax Reform on Water Resources in China

2021 ◽  
Author(s):  
Zi-rui Chen ◽  
Pu-yan Nie
Keyword(s):  
Water Resources ◽  
Water Resource ◽  
Tax Reform ◽  
Low Cost ◽  
Production Capacity ◽  
Cost Difference ◽  
Tax Rate ◽  
Leading Position ◽  
Resource Policy ◽  
The Cost

Abstract Background: The Resource Tax Law has been officially implemented on September 1, 2020 in China. This law presents the “Fee-to-Tax” reform of water resources. Methods: This article compares the effects of the “Fee-to-Tax” reform under an asymmetric duopoly with perfect information. Results: First, an analysis when all firms simultaneously respond to the water resource policy is conducted. The mechanisms of the two policies are different: the water resource fee affects output by reducing market size, while the water resource tax reduces output by amplifying the weighted cost difference effects between companies. It is shown that the tax works better than the fee for eliminating backward production capacity. Then, a comparison of the situation when companies respond sequentially is carried out. When a low-cost firm is in the leading position, the collection of fees actually reduces the output difference, whereas the tax improves it. When a high-cost firm acts as a leader, the effects depend on the cost difference. When the cost difference between firms is small, the first-move advantage of high-cost firms dominates the cost advantages of low-cost firms. Therefore, a higher tax rate yields a smaller output difference. Conclusions: When cost differences are relatively larger, the cost advantage of low-cost firms dominates the first-move advantage of high-cost firms. Therefore, the “Fee-to-Tax” reform provides some benefits to maintain the environmental development of some water-mining or related industries.

scholarly journals Digital Vein Mapping Using Augmented Reality

2020 ◽  
Vol 13 (6) ◽  
pp. 512-521
Author(s):  
Mohamed Taha ◽  
◽  
Mohamed Ibrahim ◽  
Hala Zayed ◽  
◽  
...  
Keyword(s):  
Augmented Reality ◽  
Real Time ◽  
Infrared Radiation ◽  
Low Cost ◽  
Economic Cost ◽  
Frame Rate ◽  
Infrared Light ◽  
Real Time Processing ◽  
And Gender ◽  
Time Systems

Vein detection is an important issue for the medical field. There are some commercial devices for detecting veins using infrared radiation. However, most of these commercial solutions are cost-prohibitive. Recently, veins detection has attracted much attention from research teams. The main focus is on developing real-time systems with low-cost hardware. Systems developed to reduce costs suffer from low frame rates. This, in turn, makes these systems not suitable for real-world applications. On the other hand, systems that use powerful processors to produce high frame rates suffer from high costs and a lack of mobility. In this paper, a real-time vein mapping prototype using augmented reality is proposed. The proposed prototype provides a compromised solution to produce high frame rates with a low-cost system. It consists of a USB camera attached to an Android smartphone used for real-time detection. Infrared radiation is employed to differentiate the veins using 20 Infrared Light Emitting Diodes (LEDs). The captured frames are processed to enhance vein detection using light computational algorithms to improve real-time processing and increase frame rate. Finally, the enhanced view of veins appears on the smartphone screen. Portability and economic cost are taken into consideration while developing the proposed prototype. The proposed prototype is tested with people of different ages and gender, as well as using mobile devices of different specifications. The results show a high vein detection rate and a high frame rate compared to other existing systems.

scholarly journals Efficiency Evaluation for Femtocell Spectrum Access in LTE-Advanced

2015 ◽  
Vol 1 (1) ◽  
pp. 96-111
Author(s):  
Omar Arafat ◽  
Mark A Gregory
Keyword(s):  
Performance Analysis ◽  
Low Cost ◽  
Limited Area ◽  
Femtocell Networks ◽  
Indoor Coverage ◽  
Lte Advanced ◽  
Femtocell Network ◽  
Increasing Demand ◽  
Resource Allocation Scheme

Femtocells are considered one of the ultimate solutions for the ever increasing demand in LTE-Advance. Recently, wireless industries have resorted to femtocell networks in order to enhance indoor coverage and quality of service since macro-antennas fail to reach these objectives. In enabling indoor home or enterprise users with mobile broadband solutions, role of femtocells are crucially important. While considering low cost solutions for higher coverage and data rate, femtocells apparently have one of the best potentials for indoor users. Due to the dense self-deployment of femtocells in a limited area, serious inter-femtocell interference (IFI) may cause, which consequently results in severe performance degradation. To mitigate the IFI and utilize spectrum resource more efficiently, this paper proposes a cluster based femtocell deployments along with a capacity based cognitive resource allocation scheme .Three different channel configurations in a hybrid access femtocell network are considered for performance analysis. The results of a performance analysis of the cluster based femtocell configurations in a priority based users’ network are presented.

scholarly journals Guidance Stabilization of Satellites Using the Geomagnetic Field

2012 ◽  
Vol 2012 ◽  
pp. 1-9
Author(s):  
Francisco Miranda
Keyword(s):  
Geomagnetic Field ◽  
Technological Development ◽  
Low Cost ◽  
Low Earth Orbit ◽  
Earth Orbit ◽  
Small Satellites ◽  
Attitude Stabilization ◽  
Short Period ◽  
Low Earth Orbit Satellite ◽  
Games Theory

In the last years the small satellites have played an important role in the technological development. The attractive short period of design and low cost of them and the capacity to solve problems that are usually considered as problems to big and expensive spacecrafts lead us to study the control problem of these satellites. Active three-axis magnetic attitude stabilization of a low Earth orbit satellite is considered in this work. The control is created by interaction between the magnetic moment generated by magnetorquers mounted on the satellite body and the geomagnetic field. This problem is quite complex and difficult to solve. To overcome this difficulty guidance control is considered, where we use ε-strategies introduced by Pontryagin in the frame of differential games theory. Qualitative analysis and results of numerical simulation are presented.

Input reflection coefficient of a basic dielectric-filled edge-slot antenna

2005 ◽  
Author(s):  
D. Sengupta ◽  
L. Martins-Camelo ◽  
H. Jones ◽  
D. Schaubert
Keyword(s):  
Reflection Coefficient ◽  
Slot Antenna

Reconfigurable Antenna

2016 ◽  
pp. 237-263
Author(s):  
Mohamad Kamal A Rahim ◽  
Huda A. A. Majid ◽  
Mohamad Rijal Hamid
Keyword(s):  
Communication Systems ◽  
Low Cost ◽  
Wireless Systems ◽  
Reconfigurable Antennas ◽  
Effective Length ◽  
Slot Antenna ◽  
Wireless Communication Systems ◽  
Reconfigurable Antenna ◽  
5 Ghz ◽  
Narrow Bands

Reconfigurable antennas have attracted a lot of attention especially in future wireless communication systems. Superior features such as reconfigurable capability, low cost, multi-purpose functions and size miniaturization have given reconfigurable antennas advantage to be integrated into a wireless systems. In this chapter, two types of reconfigurable antennas are discussed. First, frequency reconfigurable narrowband microstrip slot antenna (FRSA) is presented. The proposed antenna is designed to operate at six reconfigurable frequency bands from 2 GHz to 5 GHz with bidirectional radiation pattern. The second antenna design is frequency reconfigurable narrowband patch-slot antenna (FRPSA) is presented. The antenna is a combination of a microstrip patch and slot antenna. Nine different narrow bands are produced by tuning the effective length of the slot. The performances of the antenna in term of simulated and measured results are presented. In conclusion, good agreement between the simulated and measured results has been attained.

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