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Broadband planar dipole array Antenna with double C‐shaped slit elements for digital TV broadcasting transmission 下载免费PDF全文
This research has proposed a planar rectangular dipole antenna enclosed in double C‐shaped parasitically slit elements (i.e., radiator element) on a double‐cornered reflector for bandwidth enhancement. In the study, simulations were first carried out to determine the optimal parameters of the radiator element and then a radiator element prototype was fabricated and mounted onto a double‐cornered aluminum reflector. The simulated and measured |S11|<–10 dB of the antenna element covered the frequency ranges of 451–901 MHz (66.6%) and 455–886 MHz (64.3%), respectively. The gain was enhanced by the subsequent deployment of multiple radiator elements to fabricate a four‐element vertically array antenna on an elongated double‐cornered reflector. The simulated and measured |S11|10 dB of the array antenna, respectively, covered the 410–991 MHz (82.9%) and 415–886 MHz (72.4%) frequency ranges. The proposed array antenna radiates unidirectionally across the DTV frequency band with a measured front‐to‐back ratio and cross polarization >20 and 23 dB, respectively. The simulated and measured half‐power beam widths in the E and H planes were respectively 56° ± 13° and 20° ± 6°; and 57° ± 13° and 21° ± 6°. In addition, the simulated and measured gains of the array antenna were 12.8–16.4 dBi and 11.3–15.8 dBi along the 470–862 MHz frequency range. This proposed array antenna is thus suitable for DTV broadcasting transmission. © 2016 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:466–478, 2016. 相似文献
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Komsan Kanjanasit Pracha Osklang Terapass Jariyanorawiss Akkarat Boonpoonga Chuwong Phongcharoenpanich 《计算机、材料和连续体(英文)》2023,74(1):503-522
A 5G wireless system requests a high-performance compact antenna device. This research work aims to report the characterization and verification of the artificial magnetic conductor (AMC) metamaterial for a high-gain planar antenna. The configuration is formed by a double-side structure on an intrinsic dielectric slab. The 2-D periodic pattern as an impedance surface is mounted on the top surface, whereas at the bottom surface the ground plane with an inductive narrow aperture source is embedded. The characteristic of the resonant transmission is illustrated based on the electromagnetic virtual object of the AMC resonant structure to reveal the unique property of a magnetic material response. The characteristics of the AMC metamaterial and the planar antenna synthesis are investigated and verified by experiment using a low-cost FR4 dielectric material. The directional antenna gain is obviously enhanced by guiding a primary field radiation. The loss effect in a dielectric slab is essentially studied having an influence on antenna radiation. The verification shows a peak of the antenna gain around 9.7 dB at broadside which is improved by 6.2 dB in comparison with the primary aperture antenna without the AMC structure. The thin antenna profile of λ/37.5 is achieved at 10 GHz for 5G evolution. The emission property in an AMC structure herein contributes to the development of a low-profile and high-gain planar antenna for a compact wireless component. 相似文献
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Transmission electron microscopy method providing high resolution in the cell section without radiation damage 下载免费PDF全文
Jarmil Prachař 《Microscopy research and technique》2017,80(5):444-455
Several new features of mitochondrial nucleoid and its surroundings in mammalian cells were described previously (Pracha?, 2016). Very small details were observed using the improved transmission electron microscopy method, as described in the article. In the meantime, the method has again been improved to 2 Å resolutions in the cell section. The method described in detail in the present work is documented on the same records that were published in lower resolution in the work Pracha? (2016), enabling comparison of the achieved resolution with the previous one. New records are also presented, showing extremely high resolution and thus implying the importance of the method. Potential use of this method in different fields is suggested. 相似文献
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