共查询到19条相似文献,搜索用时 466 毫秒
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比幅测角具有原理简单,工程易实现的特点[1].天线沿轴向对称放置的双馈源常采用喇叭、振子等形式.然而对于倍频程带宽的超宽带情况,普通喇叭、振子天线很难满足波束相交电平要求.本文分析了超宽带工作下馈源的偏焦特性及双馈源的相对位置关系,并结合仿真和实验设计了大张角对数周期天线来作为馈源,在倍频程上实现波束相交电平近似一致的双波束. 相似文献
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分析宽频带、双极化、恒束宽四脊喇叭的混合方法 总被引:10,自引:3,他引:7
介绍了作为反射面天线馈源的宽频带、双极化、恒波束四脊喇叭,运用有限元和模式匹配相结合的混合法详细且计算了四脊喇叭的广义散射矩阵。然后运用口面积分计算了四脊喇叭的辐射远场,给出了四脊喇叭和用四脊喇叭做馈源的反射面天线的实测结果。 相似文献
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反射面天线设计的关键就是通过选择合适的喇叭馈源边缘照射电平以追求天线的高性能(增益,旁瓣电平,
效率等)。本文主要利用实例验证了标准反射面天线馈源喇叭的优选边缘照射电平,分析了赋形反射天线馈源喇叭的优选
边缘照射电平,给出了标准反射面和赋形反射面在设计中各自馈源喇叭的优选边缘照射电平。从而可以在设计工作中对
于不同形式的反射面天线有针对性的设计馈源喇叭的边缘照射电平。 相似文献
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宽带加脊喇叭天线的简化设计 总被引:4,自引:0,他引:4
加脊喇叭作为宽带天线的一种重要形式在雷达工程上的应用已愈来愈广泛。文中结合AnsoftHFSSEM软件仿真技术 ,给出了一种宽带加脊喇叭的简化设计方法 ,把加脊喇叭天线的设计分解成简单的 3个部分来进行 ,即同轴脊波导变换部分、喇叭部分、脊曲线的求解部分。该方法简化了脊曲线的求解 ,避免了繁杂的数学计算过程 ,运用Ansoft电磁场仿真软件进行优化得到较理想的结果。实测结果表明 ,这种天线在三倍频程的带宽内匹配良好 相似文献
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论述了双频共面单脉冲天线的设计方法。天线口径较小时,馈源的遮挡口径相对较大,这对天线的性能影响很大,选择口径较小的双频馈源是实现双频共面的关键。天线低频段馈源采用4喇叭单脉冲形式,高频段馈源采用单口多模单脉冲喇叭,通过各自的馈电网络实现单脉冲功能。天线采用卡塞格伦形式,通过对天线和馈源的优化设计,可实现天线双频段工作性能,实测结果与计算结果基本吻合。 相似文献
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本文提出一种新颖的正交圆极化双频高效率圆锥喇叭。其原理是在光壁喇叭中放置两个相距一定间隔的介质带。在低频区工作时,基本上只有靠近喇叭口径的介质带对辐射图的等化作出贡献;而在高频区,两个介质带共同对辐射图的等化作出贡献。适当选择这两个介质带的尺寸,即可在高、低频区都获得波瓣等化、旁瓣电平低的喇叭方向图。从而,把“介质加载”技术推广到双频圆极化的应用。 文中介绍了一个设计实例。该喇叭工作于频率比为1:1.40的两个频区中。在每个频区中,方向图的等化带宽约为10%。输入电压驻波比在高、低频区的使用频段中分别小于1.05和1.12。 相似文献
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《电子科技文摘》2002,(8)
0215340·光纤的偏振模色散及测量〔刊〕/唐月刀广播与电视技术一2002,29(3).一54一158(L) 02 15346伏拉索夫模式变换器数值计算〔刊〕/袁成卫刀国防科技大学学报一2002,24(2)一106一110(K) 0215341分析宽频带、双极化、恒束宽四脊喇叭的混合方法〔刊〕/何山红//电波科学学报一2002,17(2)一160一165(L) 介绍了作为反射面夭线馈源的宽频带、双极化、恒波束四脊喇叭,运用有限元和模式匹配相结合的混合法详细推导且计算了四脊喇叭的广义散射矩阵。然后运用口面积分计算了四脊喇叭的辐射远场,给出了四脊喇叭和用四脊喇叭做馈源的反射面天线的… 相似文献
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Kumaran Natesan Ramesh Subramaniam Chitra Sivathanu 《International Journal of Communication Systems》2023,36(14):e5551
A reconfigurable MIMO antenna for heterogeneous vehicular networks is reported in this paper. The frequency and bandwidth characteristics of the MIMO antenna can be reconfigured to meet multi-standard and multi-frequency requirements in automobiles. The antenna element evolved from an edge-chamfered ultra-wideband (UWB) antenna operating from 2.1 to >15 GHz. The bandwidth reconfiguration is achieved through the selection of excitation paths connecting the feed and radiator. The feedline selection is performed using PIN diodes, making the antenna operate in three distinct modes, namely, UWB mode (Mode 1: 2.1–>15 GHz), industrial, scientific and medical/Internet of Things (ISM/IoT) mode (Mode 2: 2.45 GHz), and wireless local area network (WLAN) mode (Mode 3: 5–6 GHz). The feed path corresponding to Mode 2 and Mode 3 is incorporated with a suitable filtering network to shape the frequency response of the antenna based on the user's requirements. Owing to the requirement of cognitive selection of frequency bands, the frequency tunability in Mode 2 is realized using varactor diodes. The varactor-incorporated feed path reconfigures the center frequency between 2.45 and 3.5 GHz. The proposed MIMO antenna offers gain and total efficiency greater than 2.94 dBi and 76%, respectively. The prototype of the 4-port MIMO antenna is being fabricated to test its functionality in real time. 相似文献
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Jae-Young Chung Chi-Chih Chen 《Antennas and Propagation, IEEE Transactions on》2008,56(6):1541-1547
A dielectric rod antenna (DRA) design that consists of two concentric dielectric cylinders and achieves more than 4:1 bandwidth is described. The new DRA is composed of a launcher section, followed by a waveguide section and ends in a radiation section. The utilization of two-layer structure avoids the excitation of high-order modes, thus extending the operational bandwidth. Properly chosen radii and dielectric constants of each layer in conjunction with a properly tapered radiation tip ensure frequency-insensitive radiation properties (gain and pattern) and stable phase center. The design example of a two-layer dual-polarization DRA presented in this paper operates from 2 to 8 GHz and produces symmetric radiation patterns with half-power beamwidth greater than 55deg. The current design is one of the most ideal antennas to be used as a near-field probe or reflector feed. 相似文献
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Kaushal Mukherjee Subhadeep Mukhopadhyay Sahadev Roy 《International Journal of Communication Systems》2022,35(1):e5021
A small wideband Y-shaped antenna is presented in this paper. A monopole of Y-shaped with two rectangular-shape frequency shifting strip is used to produce a compact dimension of 10 mm × 12 mm on a 1-mm-thick FR4 substrate. The antenna has an impedance bandwidth (measured below ?10 dB from 39.57 to 44.63 GHz), a gain more than 4.9 dB, radiation efficiency of 81%, and voltage standing wave ratio (VSWR) < 2, within the bandwidth of interest, making it a viable option for 5G applications. The use of a (01.7850 × 2.6775 × 00.02) mm3 metallic strip located above the feed line is also shown to efficiently increase the antenna bandwidth to values greater than 5 GHz without affecting the other antenna parameters. Additionally, the measured results in comparison with the simulated results reveal negligible changes, confirming that the proposed antenna is also suitable for the applications of 5G with Internet of Things. 相似文献
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The characteristics of an annular-ring microstrip antenna operating in TM11 and TM12 modes are determined experimentally. Our results confirm the main conclusions of a theoretical study published recently by Ali, Chew and Kong and show that: (a) the bandwidth of the TM11 mode is very small while that of the TM12 mode is relatively large, and (b) the lauching efficiency of the TM12 mode is highly sensitive to the feed position while that of the TM11 mode is virtually independent of the feed position. 相似文献
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设计了一种应用于雷达系统中的低成本低副瓣阵列天线, 该天线阵包含256个辐射单元, 由四个64单元的子阵组成, 采用波导合成网络进行功率合成.天线单元采用空气同轴馈电的角锥喇叭, 空气同轴馈线内外导体呈方型结构, 其终端为短路馈电方式, 实现了内导体的自支撑设计和较低的传输损耗, 并依据综合幅度分布采用若干数量的不等功分器进行低副瓣设计.测试结果表明, 小于2的驻波带宽为0.5 GHz, 相对带宽为7.5%.另外, 中心频率的增益为30 dB, 增益大于29.5 dB的带宽为0.2 GHz, E面和H面的旁瓣电平为28.5 dB和29 dB. 相似文献
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Optical down-sampling of wide-band microwave signals 总被引:1,自引:0,他引:1
Juodawlkis P.W. Hargreaves J.J. Younger R.D. Titi G.W. Twichell J.C. 《Lightwave Technology, Journal of》2003,21(12):3116-3124
Phase-encoded optical sampling allows radio-frequency and microwave signals to be directly down-converted and digitized with high linearity and greater than 60-dB (10-effective-bit) signal-to-noise ratio. Wide-band electrical signals can be processed using relatively low optical sampling rates provided that the instantaneous signal bandwidth is less than the Nyquist sampling bandwidth. We demonstrate the capabilities of this technique by using a 60-MS/s system to down-sample two different FM chirp signals: 1) a baseband (0-250 MHz) linear-chirp waveform and 2) a nonlinear-chirp waveform having a 10-GHz center frequency and a frequency excursion of 1 GHz. We characterize the frequency response of the technique and quantify the analog bandwidth limitation due to the optical pulse width. The 3-dB bandwidth imposed by a 30-ps sampling pulse is shown to be 10.4 GHz. We also investigate the impact of the pulse width on the linearity of the phase-encoded optical sampling technique when it is used to sample high-frequency signals. 相似文献
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The input impedance and the equatorial radiation patterns of a VHF cavity-backed cylindrical gap antenna are derived and compared with experiments. The experiments generally support the computations, provided that the gap dimension is neither larger than about 1/100 of a wavelength, nor so thin that mechanical tolerances in the feed design become important. The results show that the tuning, impedance bandwidth, and the radiation patterns of this antenna can be controlled very accurately by adjusting the internal radius and height of the cavity. Salient points of this antenna are its wide-band characteristics (10-percent bandwidth), its pattern circularity, and particularly the fact that it can be made an integral part of a space vehicle. 相似文献
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一种频带展宽的小型化左手偶极子天线的设计 总被引:1,自引:1,他引:0
左手传输线加载偶极子(简称左手偶极子)可以有效实现天线的小型化,但是这种天线通常带宽窄、效率低。通过采用一种渐变的梯形网络结构代替传统的非渐变的结构形式来改善天线的阻抗特性,设计了四单元的左手偶极子天线,进而拓展了天线的带宽,天线总长度为0.2。仿真和实物测试结果显示:天线同时工作在–1阶和–3阶谐振模式,|S11|≤–10 dB的阻抗带宽达到6.5%,在工作频段内(571~610 MHz),天线的增益不小于–4.25 dBi,效率大于25%。 相似文献