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Lianwen Deng Long Liu Daohan Zhou Chao Tang Shengxiang Huang Xiaohui Gao Lei-Lei Qiu 《International Journal of Communication Systems》2023,36(1):e5368
A tunable circularly polarized square patch antenna with parasitic elements is designed for a wide frequency tuning range and high gain characteristics. The proposed antenna is constructed by one main patch and four semi-elliptic parasitic units. By loading four varactor diodes and adjusting their capacitance values, the tunable feature is performed to reallocate the corresponding working frequency. Moreover, the diagonal corners of the antenna are cut and loaded with varactor diodes, which provide the appropriate perturbation between the two orthogonality modes of the antenna, so as to ensure the circular polarization characteristic in the entire operating tuning band. The experimental results demonstrate that the reflection coefficient and axial ratio are less than −13 dB and 3 dB, respectively. The proposed antenna features a relatively wide continuously tuning range of 24% within 1.9-2.3 GHz and a stable gain of over 7 dBi with a radiation efficiency of above 85%. 相似文献
105.
Neeththi Aadithiya Balakrishnan Elizabeth Caroline Britto 《International Journal of Communication Systems》2023,36(16):e5586
This research describes the detailed analysis and design of the compact complex-free structural metamaterial quad band radiating element applicable for Bluetooth, WiMAX, WLAN, and fixed-satellite service. The radiating element designed is composed of an inner angle-rotated circular Split Ring Resonator (SRR) placed within the outer square-shaped SRR interlinked by a strip to design the multiband operational characteristics and is fed by a coplanar waveguide. Suggested radiating element is imprinted over the FR4 substrate material with the electrical dimension of 28 × 31.26 × 0.8 mm3. The initial outer-closed square ring offers dual-band operation by resonating at 2.8 and 8.5 GHz frequencies, and the incorporation of a circular SRR offers quad-band operation. The unique negative permeability feature of the proposed Square and Circular Split Ring Resonator (SCSRR) structure is extracted, and its band characteristics are analyzed. Results obtained from the simulated radiating element are validated with the fabricated antenna. The measured E plane pattern resembles a numeric eight shape, and the H plane pattern is omnidirectional. Suggested SCSRR antenna offers a gain of above 3.2 dBi in all the operating bands. 相似文献
106.
In this paper, an Ultra-Wideband (UWB) planar antenna is proposed for the reinforced concrete detection, which consists of a pair of planar waterdrop arms, a microstrip to coplanar par- allel-strips transition and a shallow rectangular cavity. In order to overcome the disadvantages of the shallow cavity, some absorbing material is loaded to weaken the narrow-band effect of the cavity and the crosstalk interference. The simulated and measured results show that the proposed antenna has a large bandwidth from 0.48 GHz to 3.6 GHz with Voltage Standing Wave Ratio (VSWR) below 2 and a fractional bandwidth about 200% under the center frequency of 1.6 GHz, directional radiation char- acteristics and small late-time ringing in the time domain, which can be suitable for nondestructive detection of the reinforced concrete. 相似文献
107.
主要介绍利用超快激光技术产生和探测THz波辐射。THz波探测方法包括电光取样和空气探测。电光取样利用光学电光效应,采用探测激光偏振态的改变得到THz电场时域波形,广泛应用在TDS系统中。空气探测方法利用激光在空气中的三阶非线性效应,可以测得THz时域波形,并且该方法没有晶体的限制,因此可以探测频谱较宽的THz脉冲。产生THz的方法主要包括光电导天线、光学Dember效应、光整流和激光等离子体。其中前三者受到材料本征声子的影响,产生的THz谱宽有一定限制。倾斜激光脉冲波前入射非线性晶体光整流可以产生很强的THz波。双色飞秒激光脉冲与空气等离子体作用,可以产生较强的宽谱THz辐射,并且其谱宽与激光脉冲宽度密切相关。 相似文献
108.
昭通市电视台3+1讯道高清卫星车系统是按照国家新闻出版广电总局安全播出实施细则要求设计,即主要(单溃点)、关键设备要求冗余设计.对3+1讯道高清卫星车系统的主要视频设备和卫星传输设备性能和选择进行了详细介绍,特别是卫星传输部分的功放性能、工作方式、功放输出增益进行了详细介绍,该系统通过多次直播运行,设备安全稳定. 相似文献
109.
超宽带天线是宽带电子系统中的关键部件。本文开展了折叠缝隙对数周期天线的电磁仿真和性能实验研究。根据对数周期偶极子天线的基本原理,设计了共面波导馈电的折叠缝隙对数周期天线。采用在折叠缝隙对数周期天线的折叠缝隙单元中加载相位槽的方法,进一步改善了天线低频端的驻波特性。对相位槽加载的折叠缝隙对数周期天线进行加工测试,测试结果表明在2 GHz~18 GHz的阻抗带宽内,驻波比小于3.5,与仿真结果吻合良好。设计了基于相位槽加载的共形LPFSA,给出了具体的仿真结果。本文的研究工作为该天线的实际应用提供了技术参考。 相似文献
110.
A. K. Singh 《International Journal of Electronics》2013,100(3):237-250
Theoretical and experimental investigations carried out on shorted microstrip patch antenna for dual band operation. The investigations were carried out by varying the shorting-pin position from the edge to the centre of the patch; such an antenna provides a frequency tunability range from 0.88?GHz to 1.08?GHz for first resonance and from 2.20?GHz to 2.59?GHz for second resonance. A frequency ratio of about 2.91 to 2.2 for the two operating frequencies is observed. When the shorting-pin position is close to centre or at the centre of the patch, a single resonant frequency is observed. It is also observed that the resonant frequency of the antenna heavily depends upon the thickness of the substrate, dielectric constant of the substrate and radius of the shorting-pin. 相似文献