Similarly to other domains, maritime community requests for broadband services have been significantly increasing. Worldwide navigation footprint and the lack of practical alternatives to Satellite Communications (SAT...Similarly to other domains, maritime community requests for broadband services have been significantly increasing. Worldwide navigation footprint and the lack of practical alternatives to Satellite Communications (SATCOM) empower VHF band as the natural choice to support most of those demands. Nevertheless, the major challenge for an implementation of maritime broadband VHF services is unquestionably the spectrum availability and management. Eventually, the solution must include spectrum sharing, using a Cognitive Radio (CR) based approach, but unfortunately current regulatory framework and spectrum management regime are not appropriate for such concepts and emerging technologies. To overcome such constraints, it is necessary to address a whole field of regulatory and standardization issues in order to prepare an evolution towards a more flexible and dynamic approach to spectrum management and a transition that would ensure incumbents live operations and legacy systems. The required paradigm change encompasses a new policy definition, an enforcement mechanism implementation and a comprehensive transition plan. The presented analysis pretends to address the regulatory feasibility of a framework change, discusses its evolving process and points some challenges related with practical aspects associated to Quality of Service (QoS) enforcement metrics definition, centering the arguments in maritime VHF band.展开更多
在超短波通信系统中,经常要求天线具有宽频带与耐受大功率的特性。通过理论上的定性分析,设计了一种对称振子天线。天线阻抗匹配采用套筒式结构、与空气带状线平衡器结构一体设计。根据仿真计算结果,制作了1副天线。测试结果表明,该天线...在超短波通信系统中,经常要求天线具有宽频带与耐受大功率的特性。通过理论上的定性分析,设计了一种对称振子天线。天线阻抗匹配采用套筒式结构、与空气带状线平衡器结构一体设计。根据仿真计算结果,制作了1副天线。测试结果表明,该天线在VHF频段20%带宽内驻波比小于1.3,可以承受5 k W连续波功率要求。该匹配技术也被证明可以用于其他TEM模馈电结构的天线设计。展开更多
基于第三代半导体材料的GaN高电子迁移率晶体管(HEMT),运用传输线变压器(TLT,Transmission Line Transformer)宽带匹配技术,研制了工作于VHF/UHF频段的功率放大器。采用推挽的结构,运用TLT进行输入输出网络匹配,成功设计了一个工作于100...基于第三代半导体材料的GaN高电子迁移率晶体管(HEMT),运用传输线变压器(TLT,Transmission Line Transformer)宽带匹配技术,研制了工作于VHF/UHF频段的功率放大器。采用推挽的结构,运用TLT进行输入输出网络匹配,成功设计了一个工作于100~1000MHz,Gain≥9.28 dB,Gain flatness≤±2.65 d B,PAE≥40.3%,Pout≥100W的GaN宽带功率放大器。适用于干扰、宽带通讯等对带宽、功率要求较高的系统中。展开更多
文摘Similarly to other domains, maritime community requests for broadband services have been significantly increasing. Worldwide navigation footprint and the lack of practical alternatives to Satellite Communications (SATCOM) empower VHF band as the natural choice to support most of those demands. Nevertheless, the major challenge for an implementation of maritime broadband VHF services is unquestionably the spectrum availability and management. Eventually, the solution must include spectrum sharing, using a Cognitive Radio (CR) based approach, but unfortunately current regulatory framework and spectrum management regime are not appropriate for such concepts and emerging technologies. To overcome such constraints, it is necessary to address a whole field of regulatory and standardization issues in order to prepare an evolution towards a more flexible and dynamic approach to spectrum management and a transition that would ensure incumbents live operations and legacy systems. The required paradigm change encompasses a new policy definition, an enforcement mechanism implementation and a comprehensive transition plan. The presented analysis pretends to address the regulatory feasibility of a framework change, discusses its evolving process and points some challenges related with practical aspects associated to Quality of Service (QoS) enforcement metrics definition, centering the arguments in maritime VHF band.
文摘在超短波通信系统中,经常要求天线具有宽频带与耐受大功率的特性。通过理论上的定性分析,设计了一种对称振子天线。天线阻抗匹配采用套筒式结构、与空气带状线平衡器结构一体设计。根据仿真计算结果,制作了1副天线。测试结果表明,该天线在VHF频段20%带宽内驻波比小于1.3,可以承受5 k W连续波功率要求。该匹配技术也被证明可以用于其他TEM模馈电结构的天线设计。
文摘基于第三代半导体材料的GaN高电子迁移率晶体管(HEMT),运用传输线变压器(TLT,Transmission Line Transformer)宽带匹配技术,研制了工作于VHF/UHF频段的功率放大器。采用推挽的结构,运用TLT进行输入输出网络匹配,成功设计了一个工作于100~1000MHz,Gain≥9.28 dB,Gain flatness≤±2.65 d B,PAE≥40.3%,Pout≥100W的GaN宽带功率放大器。适用于干扰、宽带通讯等对带宽、功率要求较高的系统中。
