Design Of 10 Ghz Negative Resistance Dielectric Resonator Oscillator

Pasaran komunikasi wayarles telah mengalami pertumbuhan yang luar biasa dan memandangkan bilangan pengguna wayarles dan jumlah gangguan RF terus meningkat, piawaian komunikasi moden memerlukan hingar fasa berprestasi unggul daripada pengayun tempatan dalam pemancar dan penerima. The wireless communication market has been experiencing tremendous growth and since the number of wireless subscribers and the amount of RF interference continue to increase, modern communication standards demand excellent phase noise performance from local oscillators in transceivers. Noise is one of major concern in oscillators because even a small amount of noise in an oscillator leads to dramatic changes in its frequency spectrum and timing properties. In general, an oscillator‟s phase noise determines the overall communication system‟s capabilit

低地球軌道コンステレーションの追跡のための適応アンテナアレイ実装のシミュレーション

Since Low Earth Orbit has become an in orbit to place satellites, CubeSat constellation tracking is challenging. Higher capacity and capability of a new Ground Station tracking system are in demand and this, motivates researchers to come out with a solution to mitigate the traditional Ground Station degradation performance. This paper discusses the Least Mean Square algorithm\u27s implementation in Adaptive Array Antenna for the Ground Station tracking system application. The simulation results show the capability of the main beam pattern to perform instantaneous tracking and steering towards the targeted CubeSat while suppressing the side lobes towards the other interfering CubeSats when a massive CubeSats constellation take place. Planar and circular array antennas are analyzed by setting the optimum weighting factors to be adapted. Three scenarios of CubeSats constellations are simulated. The performance of the Adaptive Array Antenna for each scenario is analyzed based on the beam width characteristics and the Signal-to-Interference Ratio of the beam pattern. The number of CubeSats tracked by the Adaptive Array Antenna and the capability of the system to perform fast-tracking as the number of antenna array elements is increased also discussed in this paper. Finally, solutions to mitigate the limitation of the Least Mean Square algorithm to perform fast-tracking when massive interferer CubeSats are nearby are proposed.九州工業大学博士学位論文 学位記番号：工博甲第507号 学位授与年月日：令和2年9月25日1 INTRODUCTION|2 THEORETICAL BACKGROUND AND LITERATURE REVIEW|3 RESEARCH METHODOLOGY|4 RESULTS AND DISCUSSION|5 CONCLUSION AND RECOMMENDATION九州工業大学令和2年

低地球軌道コンステレーションの追跡のための適応アンテナアレイ実装のシミュレーション

九州工業大学博士学位論文（要旨）学位記番号：工博甲第507号 学位授与年月日：令和2年9月25

Implementation of Adaptive Antenna Array for Ground Station Tracking System

As the number of small satellites keeps increasing due to the low-cost development and fast delivery duration, there is a demand for higher capacity and capability of the ground station tracking system. Generally, the existing ground station tracking system faces major performance degradation while tracking satellites because of signals interference and multi-path fading. These problems motivate researchers to come out with interesting solution to mitigate the degradation performance. This paper describes the implementation of adaptive beam forming algorithm of phased array antenna for ground station tracking system. The adaptive antenna array demonstrates electronically self-steering radiation pattern capability towards satellites signals, suppress interferences and multi-path signals. This can be achieved by adapting the Least Mean Square (LMS) algorithm by varying the number and phase of the array antenna elements and the angle of beam steering to determine the Direction of Arrival (DOA) of incoming signals. The performance of adaptive LMS algorithm is investigated in MATLAB software by analyzing the radiation patterns for different number of array antenna elements, phases and beam steering angle. The purpose of LMS algorithm implementation in the Adaptive Array Antenna (AAA) system is to control weights adaptively, optimize the Signal to Noise Ratio (SNR) of the desired signal and minimize the Mean Square Error (MSE).32nd International Symposium on Space Technology and Science, June 15-21, 2019, Fukui, Japa

Strong and widespread cycloheximide resistance in Stichococcus-like eukaryotic algal taxa

This study was initiated following the serendipitous discovery of a unialgal culture of a Stichococcus-like green alga (Chlorophyta) newly isolated from soil collected on Signy Island (maritime Antarctica) in growth medium supplemented with 100 µg/mL cycloheximide (CHX, a widely used antibiotic active against most eukaryotes). In order to test the generality of CHX resistance in taxa originally identified as members of Stichococcus (the detailed taxonomic relationships within this group of algae have been updated since our study took place), six strains were studied: two strains isolated from recent substrate collections from Signy Island (maritime Antarctica) (“Antarctica” 1 and “Antarctica” 2), one isolated from this island about 50 years ago (“Antarctica” 3) and single Arctic (“Arctic”), temperate (“Temperate”) and tropical (“Tropical”) strains. The sensitivity of each strain towards CHX was compared by determining the minimum inhibitory concentration (MIC), and growth rate and lag time when exposed to different CHX concentrations. All strains except “Temperate” were highly resistant to CHX (MIC > 1000 µg/mL), while “Temperate” was resistant to 62.5 µg/mL (a concentration still considerably greater than any previously reported for algae). All highly resistant strains showed no significant differences in growth rate between control and treatment (1000 µg/mL CHX) conditions. Morphological examination suggested that four strains were consistent with the description of the species Stichococcus bacillaris while the remaining two conformed to S. mirabilis. However, based on sequence analyses and the recently available phylogeny, only one strain, “Temperate”, was confirmed to be S. bacillaris, while “Tropical” represents the newly erected genus Tetratostichococcus, “Antarctica 1” Tritostichococcus, and “Antarctica 2”, “Antarctica 3” and “Arctic” Deuterostichococcus. Both phylogenetic and CHX sensitivity analyses suggest that CHX resistance is potentially widespread within this group of algae

Aliinostoc bakau sp. nov. (Cyanobacteria, Nostocaceae), a New Microcystin Producer from Mangroves in Malaysia

A new microcystin-producing mangrove cyanobacterium, Aliinostoc bakau sp. nov., was isolated from a tropical mangrove in Penang, Malaysia, and characterized using combined morphological and phylogenetic approaches. Cultures were established in liquid media of different salinities (0, 7, 14, 21, 28, and 35 ppt). Optimal growth observed at both 7 and 14 ppt was consistent with the origin of the strain from an estuarine mangrove environment. Phylogenetic analysis based on the 16S rRNA gene strongly indicated that the strain is a member of the genus Aliinostoc and is distinct from other currently sequenced species in the genus. The sequences and secondary structure of the 16S–23S ITS region D1–D1’ and Box–B helices provided further confirmation that the new species is clearly distinct from previously described Aliinostoc species. Amplification of the mcyE gene fragment associated with the production of microcystin in A. bakau revealed that it is identical to that in other known microcystin-producing cyanobacteria. Analysis of the extracts obtained from this strain by HPLC-MS/MS confirmed the presence of microcystin variants (MC-LR and -YR) at concentrations of 0.60 μg/L and MC-RR at a concentration of 0.30 μg/L. This is the first record of microcystin production from Aliinostoc species in tropical mangrove habitats

Discovery of microcystin-producing Anagnostidinema pseudacutissimum from cryopreserved Antarctic cyanobacterial mats

Microcystins (MCs) are secondary metabolites produced by cyanobacteria and have been well-documented in temperate and tropical regions. However, knowledge of the production of MCs in extremely cold environments is still in its infancy. Recently, examination of 100-year-old Antarctic cyanobacterial mats collected from Ross Island and the McMurdo Ice Shelf during Captain R.F. Scott's Discovery Expedition revealed that the presence of MCs in Antarctica is not a new phenomenon. Here, morphological and molecular phylogenetic analyses are used to identify a new microcystin-producing freshwater cyanobacterium, Anagnostidinema pseudacutissimum. The strain was isolated from a deep-frozen (−15 °C) sample collected from a red-brown cyanobacterial mat in a frozen pond at Cape Crozier (Ross Island, continental Antarctica) in 1984–1985. Amplification of the mcyE gene fragment involved in microcystin biosynthesis from A. pseudacutissimum confirmed that it is identical to the sequence from other known microcystin-producing cyanobacteria. Analysis of extracts from this A. pseudacutissimum strain by HPLC-MS/MS confirmed the presence of MC-LR and -YR at concentrations of 0.60 μg/L and MC-RR at concentrations of 0.20 μg/L. This is the first report of microcystin production from a species of Anagnostidinema from Antarctica

Microcystin production by oscillatorialean cyanobacteria isolated from cryopreserved Antarctic mats

Twenty cyanobacterial strains of eight morphospecies isolated from deep-frozen (-15 °C) mat samples originally collected on Ross Island, in Victoria Land, and on the McMurdo Ice Shelf were screened for the presence of genes encoding for production of anatoxins, cylindrospermopsin, microcystin/nodularin and saxitoxin. One strain of each of Microcoleus autumnalis and Phormidesmis priestleyi and two strains of Wilmottia murrayi were found to produce microcystin. No toxin production was detected in the other 16 strains representing five species. The four toxin-producing strains were characterised using both morphological and molecular approaches. Phylogenetic analyses using partial 16S rRNA sequences were consistent with the morphological identification of all four strains. They were all found to contain a fragment of the mcyE gene, which is involved in microcystin biosynthesis. ELISA analysis of extracts from cultures of these strains confirmed the presence of low concentrations of microcystin: 0.35 μg/L in M. autumnalis, <0.15 μg/L in P. priestleyi, 1.60 μg/L in W. murrayi strain 1 and 0.9 μg/L in W. murrayi strain 2. This study includes the first report of microcystin synthesis by W. murrayi

Implementation of Adaptive Antenna Array for Ground Station Tracking System

As the number of small satellites keeps increasing due to the low-cost development and fast delivery duration, there is a demand for higher capacity and capability of the ground station tracking system. Generally, the existing ground station tracking system faces major performance degradation while tracking satellites because of signals interference and multi-path fading. These problems motivate researchers to come out with interesting solution to mitigate the degradation performance. This paper describes the implementation of adaptive beam forming algorithm of phased array antenna for ground station tracking system. The adaptive antenna array demonstrates electronically self-steering radiation pattern capability towards satellites signals, suppress interferences and multi-path signals. This can be achieved by adapting the Least Mean Square (LMS) algorithm by varying the number and phase of the array antenna elements and the angle of beam steering to determine the Direction of Arrival (DOA) of incoming signals. The performance of adaptive LMS algorithm is investigated in MATLAB software by analyzing the radiation patterns for different number of array antenna elements, phases and beam steering angle. The purpose of LMS algorithm implementation in the Adaptive Array Antenna (AAA) system is to control weights adaptively, optimize the Signal to Noise Ratio (SNR) of the desired signal and minimize the Mean Square Error (MSE).32nd International Symposium on Space Technology and Science, June 15-21, 2019, Fukui, Japa

Design of a negative conductance dielectric resonator oscillator for X-band applications

An X-band tunable microwave low-phase noise planar oscillator employing a novel-fed dielectric resonator (DR) with a single transistor has been investigated and realized. A ZrSnTi oxide composite ceramic-based DR with dielectric permittivity of 95 enclosed in a metallic cavity with an unloaded Q factor of 5,000 at 10 GHz is proposed. The resonant frequency affinity with respect to geometric parameters is established by using the compensation technique based on dual negative conductance feedback, the outputs of which are combined via a Wilkinson power divider (WPD). The feedback parallel-coupled DR oscillator is incorporated into a laminate microwave board using the photolithographic technique. The oscillator includes a pseudomorphic low noise amplifier based on a high-electron-mobility transistor. Hence, the proposed oscillator with mechanic tuning is measured, and the results show that DR resonates at TE01d mode with frequency of 10 GHz. The measured phase noise of the oscillator is –81.03 dBc/Hz at a 100 kHz offset