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1.
The traditional mobile phone antenna has many disadvantages, such as complicated structure, high profile, large size. In order to reduce the size of a mobile phone antenna, a novel miniaturized mobile phone antenna with a hendeca-band is presented in this paper by studying the method of frequency band broadening of the miniaturized low profile dual layer microstrip antenna. The size of the presented antenna is only 37.0mm×7.2mm. First, by using the monopole and the ground strip coupling technologies to excite the resonant mode, the high-frequency bandwidth of the antenna is broadened. Then, the low-frequency bandwidth of the antenna is also broadened by using the loading inductance method to shift low-frequency resonance. The measured results have demonstrated that eight LTE/WWAN bands can be covered and that the S11 of the proposed antenna is lower than -10dB in the range of GPS, WiFi and Bluetooth bands. Compared with traditional microstrip antennas, the proposed antenna has good radiation gain and efficiency as well as the small size, simple structure and wide frequency band.  相似文献   
2.
《Ceramics International》2019,45(11):14312-14315
In this work, an Al powder was coated with antimony-doped tin oxide (ATO) to obtain an infrared-laser compatible stealth material. The composites are prepared via a coprecipitation method, characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD), and measured by ultraviolet spectrophotometer and dual band infrared emissometer. The morphology and microstructure show that the flaky Al powder was coated by the ATO nanoparticles and doped into the SnO2 rutile structure by an Sb5+ ion. The optimal Al content was 20%, and the optimized Sn/Sb molar ratio was 10: 1. Meanwhile, the reflectivity of the composites was 43.454%, and the infrared emissivity in 8–14 μm far infrared waveband range was 0.708. It may shed light on a new material design orientation to obtain high performance laser-infrared compatible stealth materials.  相似文献   
3.
水性红外隐身涂料制备工艺优化   总被引:2,自引:2,他引:0  
目的优化水性红外隐身涂层材料制备工艺,提高低发射率红外隐身涂料隐身性能。方法采用红外辐射率测量仪、红外光谱吸收仪等,研究涂层固化温度、涂层表面粗糙度和涂层厚度对低发射率红外隐身涂料隐身性能的影响。结果固化温度对涂层红外发射率和基体树脂红外吸收光谱影响不大,但随着固化温度升高,涂层固化时间明显缩短;随着涂层表面粗糙度的增加,涂层红外发射率增加;表面粗糙材料红外发射率受测试角度影响小于表面光滑材料;在基材上制备不同厚度的涂层,当涂层厚度小于30μm时,涂层红外发射率受基材表面红外发射率影响较大,当大于30μm时,影响较小。结论可以根据实际时间需求选择合适的涂层固化温度,宜选择刮涂方式使涂层表面保持一定的粗糙度,涂层厚度宜为30~40μm。  相似文献   
4.
为解决机翼翼尖等弱散射源所带来的雷达散射截面(RCS)贡献问题,针对典型机翼设计了几种不同的机翼翼尖方案,建立了典型翼尖数值模型。利用基于多层快速多极子算法(MLFMA)的FEKO软件,计算、分析不同方案翼尖外形在不同频段、不同方位角下的RCS量级,并优选出对机翼RCS贡献最低的翼尖外形方案。计算结果表明,针对典型机翼,从翼尖到翼根方向上15%处顺气流直切的翼尖外形方案,其翼尖尖点所带来的RCS贡献最小。  相似文献   
5.
通过高温固相法制备了SmCrO3粉体材料,利用光谱漫反射率、色坐标、激光雷达截面比等参数对材料隐身效果进行评估。结果表明,在1400 ℃煅烧温度下,厚度为0.2 mm的材料样品在1.06 μm和1.55 μm均出现较强的吸收峰,吸收率分别为54%和53%;外表呈现浅绿色的样品色坐标变化范围很小(0.3588±0.0007,0.3792±0.0081);激光雷达截面比基本保持在1.8以上,并随着煅烧温度升高,该比值不断上升,表明对激光的吸收能力不断增强。因此,SmCrO3粉体是一种兼容可见迷彩和近红外激光的优良隐身材料。  相似文献   
6.
In this study, we investigated the validity of a stealth assessment of physics understanding in an educational game, as well as the effectiveness of different game-level delivery methods and various in-game supports on learning. Using a game called Physics Playground, we randomly assigned 263 ninth- to eleventh-grade students into four groups: adaptive, linear, free choice and no-treatment control. Each condition had access to the same in-game learning supports during gameplay. Results showed that: (a) the stealth assessment estimates of physics understanding were valid—significantly correlating with the external physics test scores; (b) there was no significant effect of game-level delivery method on students' learning; and (c) physics animations were the most effective (among eight supports tested) in predicting both learning outcome and in-game performance (e.g. number of game levels solved). We included student enjoyment, gender and ethnicity in our analyses as moderators to further investigate the research questions.  相似文献   
7.
《Ceramics International》2022,48(21):31389-31396
With the development of laser technology, laser-related materials have been widely studied. Both laser stealth coatings and laser protective coatings are currently the focus of attention. However, less research has been done on laser stealth and protective integrated coatings. In this paper, plasma-sprayed Y2O3–Ti3AlC2 coatings were prepared with low-power (LP) and high-power (HP) parameters, and their laser stealth and laser protection properties were characterized. The LP coating and HP coating appeared to have lower reflectivity at 1064 nm because a low-reflectivity second phase and many loose flocs on the surface are introduced, which indicates excellent laser stealth performance. When irradiated by a laser, the LP coating exhibited excellent laser protection ability, and its reflectivity increased after irradiation because Ti3AlC2 oxidized and decomposed and densely arranged small particles formed on the surface. The LP coating perfectly protected the 500-W laser irradiation for 20 s. In addition, the laser damage threshold of the LP coating was 5.599 s at 1000-W laser irradiation, which indicates that the LP Y2O3–Ti3AlC2 coating is a potential material with laser stealth and laser protection integration.  相似文献   
8.
随着飞行器飞行速度和发动机燃烧室温度的提高, 金属类隐身涂层材料已无法满足环境使用要求。 CeO2 具有较高熔点、 抗氧化、 较低红外发射率等特点, 被认为是红外隐身应用的候选材料, 但其发射率仍无法满足 高温红外隐身需求。 本文通过固相反应法对 CeO2 进行 La3+ 掺杂改性, 研究掺杂量对 CeO2 粉体红外发射性能的 影响规律。 结果表明, 随着掺杂量从 10 mol% 增加到 30 mol%, 粉体在 3~6 μm 波段的发射率不断降低, 其中 Ce0.7La0.3O2 的红外发射率仅为 0.1。  相似文献   
9.
机载雷达射频隐身技术对提高飞行器生存能力具有重要意义。 本文研究了机载相控阵雷达基于射频隐身的搜索控制参量优化设计。通过分析截获概率原理 ,给出了目标特征和雷达系统性能对驻留时间和波位间隔等搜索控制参量的影响关系,构建 了目标探测性能与隐身性能约束下的优化模型。仿真获得了满足隐身要求下相控阵雷达的最 优搜索控制参数。  相似文献   
10.
概述了量子雷达技术发展的背景及其技术特征,对单光子量子雷达和纠缠光子量子雷达进行了简要介绍。在对美国量子雷达技术研究现状分析的基础上,重点介绍了美国罗切斯特大学的量子雷达研究与试验情况。最后,分析了量子雷达技术的未来应用及其对导弹武器的影响。  相似文献   
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