An Investigation on High Frequency Permeability of Polycrystalline Ferrities

2015 ◽  
Vol 2 ◽  
pp. 194
Author(s):  
Janis Jankovskis ◽  
Nikolajs Ponomarenko ◽  
Pavels Narica
Keyword(s):  
Eddy Current ◽  
High Frequency ◽  
Magnetic Loss ◽  
Large Body ◽  
Total Loss ◽  
Complex Permeability ◽  
Actual Structure ◽  
Important Progress

The problem under examination is the magnetic loss of polycrystalline ferrites. Their total loss include: hysteresis, eddy current and anomalous (AN) or excess ones. The mentioned first two losses more or less adequately are covered by modified Steinmetz equation whereas AN loss is less well understood. Conceptually this loss is defined by the components of complex permeability spectra of ferrites which as a rule are experimentally obtained. Large body of these experimental spectra shows a great variety of forms and specific features. This variety is the main reason why there still is not adequate analytic presentation of AN loss. It is shown in the research that important progress is possible to achieve in analytic presentation of AN loss on the basis of realistic account of microstructure of polycrystalline ferrites and dividing the variety of all samples into subgroups according to their actual structure.

Investigation on the Effect of Total Loss Reduction of HV Power Module by Using SiC-MOSFET Embedding SBD

2020 ◽  
Vol 1004 ◽  
pp. 801-807
Author(s):  
Takaaki Tominaga ◽  
Shiro Hino ◽  
Yohei Mitsui ◽  
Junichi Nakashima ◽  
Koutarou Kawahara ◽  
...  
Keyword(s):  
High Frequency ◽  
Minority Carrier ◽  
Total Loss ◽  
Loss Reduction ◽  
Carrier Injection ◽  
Power Module ◽  
Chip Area ◽  
Dc Characteristics ◽  
High Frequency Operation ◽  
Switching Characteristics

A total loss reduction of 3.3 kV power module by using SiC-MOSFET embedding SBD has been demonstrated through the investigation of DC characteristics and switching characteristics. Despite 1.1 times larger on-resistance than that of conventional SiC-MOSFET due to larger cell pitch, superior switching characteristics of SiC-MOSFET embedding SBD, which are due to smaller total chip area than that of SiC-MOSFET coupled with external SBD and due to elimination of recovery charge by minority carrier injection compared with SiC-MOSFET utilizing its body diode, enable the total loss reduction especially for high frequency operation.

Considering the Case for Diversity in Natural Resources

BioScience ◽  
2020 ◽  
Vol 70 (8) ◽  
pp. 708-718
Author(s):  
Chelsea Batavia ◽  
Brooke E Penaluna ◽  
Thea Rose Lemberger ◽  
Michael Paul Nelson
Keyword(s):  
Social Justice ◽  
Natural Resources ◽  
High Frequency ◽  
Large Body ◽  
Clear Thinking ◽  
Potential Risks ◽  
Diversity Discourse ◽  
Qualitative Coding

Abstract Although there is widespread support for diversity in natural resources, diversity is valued for different reasons. It is important to understand and critically examine these reasons, to ensure diversity efforts express clear thinking and appropriate motivations. We compiled recent (2000–2019) diversity literature in fisheries, forestry, range, and wildlife, and used a qualitative coding procedure to identify reasons articulated in support of diversity. We developed a subset of these reasons into formal arguments to assess their underlying beliefs and assumptions. Our analysis reveals a high frequency of instrumental arguments emphasizing the benefits of diversity for natural resources. Drawing on the large body of interdisciplinary diversity scholarship outside natural resources, we discuss the challenges and potential risks of predicating the case for diversity largely on instrumental arguments. We encourage natural resources communities to expand the diversity discourse by engaging with themes developed in interdisciplinary diversity literatures, including equity, social justice, and intersectionality.

scholarly journals Ferrite-Loaded Spidron Fractal Loop VHF Antenna for UAV Applications

2020 ◽  
Vol 10 (15) ◽  
pp. 5392 ◽  
Author(s):  
Won Bin Park ◽  
Young-Mi Park ◽  
Keum Cheol Hwang
Keyword(s):  
Frequency Band ◽  
High Frequency ◽  
Magnetic Loss ◽  
Low Frequency ◽  
Loop Antenna ◽  
High Frequency Band ◽  
Ferrite Material ◽  
Aerial Vehicle ◽  
Flat Ground ◽  
Good Agreement

In this letter, an electrically small Spidron fractal loop antenna operating in the VHF band is proposed. The ferrite material, which consists of a nickel-zinc combination, is loaded into inside of the loop antenna to increase the gain of the antenna in the low frequency band. To minimize the magnetic loss of the ferrite in the high frequency band, the amount and configuration of the ferrite are optimized using a genetic algorithm. Through this optimization step, the amount of the ferrite is decreased to 37.5% and the gain of the antenna in the high frequency band is improved. The size of the proposed antenna is 0.0242 × 0.0242 × 0.0051 λL3 at the lowest operating frequency. The proposed antenna was fabricated to verify the performance, and the simulated and measured results are in good agreement. The measured peak gains varied from −31.6 to −1.9 dBi within the measured frequency band. To examine the performance of the proposed antenna mounted on an unmanned aerial vehicle model (UAV), the antenna on a UAV was also simulated and the results were discussed. The simulated realized peak gains of the antenna on the UAV and on flat ground are similar.

scholarly journals Magnetic and Microwave Properties of Polycrystalline Gadolinium Iron Garnet

2017 ◽  
Vol 268 ◽  
pp. 287-291 ◽  
Author(s):  
Farah Nabilah Shafiee ◽  
Raba’ah Syahidah Azis ◽  
Ismayadi Ismail ◽  
Rodziah Nazlan ◽  
Idza Riati Ibrahim ◽  
...  
Keyword(s):  
Magnetic Loss ◽  
Ambient Air ◽  
High Energy ◽  
Microwave Properties ◽  
Complex Permeability ◽  
Frequency Range ◽  
Mixed Powder ◽  
Band Frequency ◽  
Suitable Material ◽  
Microwave Loss

The microwave loss in nanosized GdIG particles synthesized using mechanical alloying technique was investigated. There were very few of research on the microwave properties of nanosized particle GdIG and there is no attempt investigating on the material at C-band frequency range and its correlation with the microstructure. Gadolinium (III) iron oxide and iron (III) oxide, α-Fe2O3 were used as the starting materials. The mixed powder was then milled in a high-energy ball mixer/mill SPEX8000D for 3 hours. The samples were sintered at temperature 1200°C for 10 hours in an ambient air environment. The phase formation of the sintered samples was analyzed using a Philips X’Pert Diffractometer with Cu-Kα radiation. Complex permeability constitutes of real permeability and magnetic loss factor were measured using an Agilent HP4291A Impedance Material Analyzer in the frequency range from 10 MHz to 1 GHz. A PNA-N5227 Vector Network Analyzer (VNA) was used to obtain the information on ferromagnetic linewidth broadening, ΔH that represents the microwave loss in the samples in in frequency range of 4 to 8 GHz (C-band). The ΔH value was calculated from the transmission (S21) data acquired from VNA. The single phase GdIG showed low initial permeability and low magnetic loss when applied with low-frequency range energy. From these data, it is validated that GdIG is a suitable material for microwave devices for the high-frequency range.

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