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Enhanced terahertz emission bandwidth from photoconductive antenna by manipulating carrier dynamics of semiconducting substrate with embedded plasmonic metasurface
摘要： In this article, we demonstrate a technique to enhance the Terahertz (THz) emission bandwidth from photo-conductive antenna (PCA) based on semiconducting substrates by manipulating the surface carrier dynamics of the semiconductor. Bandwidths in PCAs are limited by the decay of the photogenerated charge carriers, which in case of SI-GaAs is in the orders of 50 picoseconds. We show, with an embedded design of plasmonic meta-surface in the photoconductive gap of a PCA, it is possible to enhance the emission bandwidths by more than 50 percent. This is due to the fact that these nano-structures act as local recombination sites for the photogenerated carriers, effectively reducing the carriers’ lifetime. Additionally, the defect sites reduce the terminal current, thereby reducing the Joule heating in the device. Furthermore, the meta-surface also facilitates higher in-coupling of the exciting infrared light on to the PCA, thereby increasing the optical-to-THz conversion efficiency of the device.
关键词： carrier dynamics,plasmonic metasurface,bandwidth enhancement,photoconductive antenna,Terahertz
更新于2025-09-16 10:30:52
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Bandwidth improvement of substrate integrated waveguide cavity-backed slot antenna with dielectric resonators
摘要： In the paper, a low profile substrate integrated waveguide based circular-shaped cavity-backed antenna is delineated to work at WLAN U-NII mid band and a slender rectangular slot is then placed at its center on the ground plane for radiation. The parent antenna radiates at 5.33 GHz with a gain of 4.9 dBi; depicting a narrow impedance bandwidth of 50 MHz. The antenna is modified by placing dielectric resonators of different shapes over the slot to enhance the bandwidth. The new antennas thus produced have an impedance bandwidth of 750 MHz with cylindrical-shaped and rectangular-shaped dielectric resonators which reflect bandwidth enhancement of 700 MHz for both the cases and an impedance bandwidth of 710 MHz with hemispherical-shaped dielectric resonator reflecting bandwidth enhancement of 660 MHz. The gain of the modified antennas is of the order of 4.7 dBi which basically indicates not much degradation in gain as compared to the parent antenna. All the antennas are delineated using Arlon AD270 substrate material with the results obtained after simulation juxtaposed with the ones obtained through measurement.
关键词： Bandwidth enhancement,WLAN U-NII mid band,Cavity-backed slot antenna,Substrate integrated waveguide,Dielectric resonator
更新于2025-09-11 14:15:04
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[IEEE 2018 IEEE International Conference on Computational Electromagnetics (ICCEM) - Chengdu, China (2018.3.26-2018.3.28)] 2018 IEEE International Conference on Computational Electromagnetics (ICCEM) - Planar Printed Quasi-Yagi Antenna Designs Using Characteristic Modes
摘要： Characteristic mode (CM) analysis is conducted in this paper to understand the physical aspects of a compact planar quasi-Yagi antenna at the lowest resonant frequency for achieving bandwidth enhancement and electrical size reduction. The quasi-Yagi antenna comprises a microstrip feeding line, a driver dipole and two parasitic strips. The driver dipole is modified by symmetrically adding two capacitive coupling structures, which are connected with the ground plane in the other end, through examining the behavior of the CMs. A capacitor with proper value is adopted in the feeding line for better impedance matching in the higher band. Through the work in this paper, the lowest frequency with VSWR < 2 is extended to 3.09 GHz from 3.65 GHz with no physical size enlarged. Its bandwidth is enhanced with a ratio of about 3.78 : 1.
关键词： bandwidth enhancement,characteristic modes,Quasi-Yagi antenna,size reduction
更新于2025-09-10 09:29:36
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[IEEE 2018 IEEE International Conference on Computational Electromagnetics (ICCEM) - Chengdu, China (2018.3.26-2018.3.28)] 2018 IEEE International Conference on Computational Electromagnetics (ICCEM) - A Miniaturized Cavity-Backed Sector Antenna with Bandwidth Enhancement for UAV Applications
摘要： A novel miniaturized cavity-backed sector antenna for VHF (Very High Frequency) applications is proposed in this paper. The proposed antenna is composed of two symmetrical meandering lines, a planar double-sector patch and a U-shaped backed-cavity. Two symmetrical meandering lines are used to achieve size reduction by connecting four ends of the double-sector patch. Moreover, a U-shaped backed-cavity is employed to improve directivity and achieve better gain. The proposed has a very compact size of 36cm×40cm×25cm (0.13λ0×0.15λ0×0.09λ0), which could bring considerable benefits for the design of UAV system. Simulated results show that the antenna achieves a return loss better than 10dB over 31% impedance bandwidth. The gain of this antenna is more than 2dBi. With features such as small size, wide bandwidth and good directivity, the proposed antenna can meet the demanding requirements to the application of UAV airborne system.
关键词： bandwidth enhancement,sector antenna,miniaturization,VHF antenna,broadband antenna
更新于2025-09-10 09:29:36
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The quest for perfect electromagnetic absorber: a review
摘要： This paper specifies a concise review of recent research and development in the context of electromagnetic absorbers. An attempt has been made to justify the need for economical and thin microwave absorbers for achieving good absorption characteristics over a wide range of frequencies within a specified band of electromagnetic spectrum. This paper mainly focuses on the challenges encountered while designing a perfect electromagnetic absorber which can absorb electromagnetic radiations of any polarization that may appear from any direction and may occur over a broader bandwidth. The absorbers which are competent enough to withstand all these challenges are capable to suppress the reflection and transmission of unknown electromagnetic radiations efficiently to the lowest possible level. Several prospects of nanotechnology in flexible absorber design are also described to enhance absorber characteristics. This paper also provides a futuristic glimpse on several applications of such absorbers for commercial and military purposes.
关键词： nanomaterial,electromagnetic absorber,polarization-insensitive absorber,Bandwidth enhancement,nanoparticle inks,flexible absorber,metamaterial
更新于2025-09-10 09:29:36
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AIP Conference Proceedings [Author(s) GREEN DESIGN AND MANUFACTURE: ADVANCED AND EMERGING APPLICATIONS: Proceedings of the 4th International Conference on Green Design and Manufacture 2018 - Ho Chi Minh, Vietnam (29–30 April 2018)] - Large bandwidth polydimethylsiloxane magnetite graphene sensor for brain tumor detection using microwave imaging algorithm
摘要： Large bandwidth of Polydimethylsiloxane (PDMS) magnetite graphene sensor is realized by addition of ferrite element. (Fe3O4). 35% of ferrite portion has been chosen to be combine with 65% of PDMS to form low permittivity (2.85) and low loss tangent (0.067) of substrate for the sensor. The sensor consists of graphene as the 4 × 1 array radiating patch, quarter-wavelength transmission line, parasitic element, partial ground and reflector while PDMS Ferrite as the substrate. The sensor recorded ultra-wide band radiation (2.5 GHz-11.2 GHz) with high energy (2.5dB-11.7dB) in microwave frequency ranges. As compared with conventional substrate (Taconic), the new substrate (PDMS-Fe3O4) recorded 25% of bandwidth enhancement as much as 2 GHz. Wide bandwidth and high energy sensor are essential in human microwave detection system for penetrating the multilayer structures by enhancing the focus of the electromagnetic energy into the desired structure. Maximum power of 11.7 dB and small dimensions of 90 mm × 45 mm made the UWB sensor suitable enough to be applied and integrated in microwave detection.
关键词： bandwidth enhancement,microwave imaging,Polydimethylsiloxane,magnetite graphene sensor,brain tumor detection
更新于2025-09-10 09:29:36
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[Institution of Engineering and Technology 12th European Conference on Antennas and Propagation (EuCAP 2018) - London, UK (9-13 April 2018)] 12th European Conference on Antennas and Propagation (EuCAP 2018) - Embedded Antenna Design on LoRa Radio for IoT Applications
摘要： This paper presents a miniaturized printed inverted-F antenna (PIFA) embedded on the circuit board of a LoRa sensor node for the internet of things (IoT) applications. On the 1.6 mm-thick board, very limited space is reserved for the antenna deployment, and therefore slots are cut on the ground to reduce operating frequency of the PIFA and create another resonance to broaden the bandwidth. Finally, the proposed antenna is optimized to operate from 402.4 MHz to 441.6 MHz with voltage standing wave ratio (VSWR) less than 3, and its realized gain over the 410-441 MHz LoRa frequency band is higher than -6 dBi.
关键词： internet of things,bandwidth enhancement,LoRa,miniaturized antenna
更新于2025-09-04 15:30:14