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Asymmetric Half-Bowtie Antennas with Tilted Beam Patterns
摘要： A novel geometrical change is introduced to a broadband bowtie antenna to allow radiation beam tilting without the use of an engineered material. By halving the bowtie arms along their horizontal axis of symmetry and judicially removing parts of it, the phase line of the antenna can be controlled to achieve various magnitudes of tilted radiation patterns. Further bandwidth improvements are realized when the traditional triangular antenna is replaced with an elliptical equivalent. Using either geometry, the amount of tilt in free space across its bandwidth could vary from 0° to 48°. For the printed case, a unidirectional antenna pattern is tilted to approximately 40° along the useable bandwidth of 32% with a peak gain of about 5 dBi and a front to back ratio greater than 10 dB. A prototype antenna is fabricated and tested. The measured results satisfactorily validate the numerical ones.
关键词： tilted radiation beams,antenna radiation patterns,Bowtie antennas
更新于2025-09-23 15:21:21
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[IEEE 2019 International Conference on Communication and Electronics Systems (ICCES) - Coimbatore, India (2019.7.17-2019.7.19)] 2019 International Conference on Communication and Electronics Systems (ICCES) - Design and performance analysis of WDM optical Communication system with EDFA-DCF and FBG for dispersion compensation using $8\mathrm{x}5$ Gbps data rate
摘要： The way in which electromagnetic ?elds are transmitted and received by ground penetrating radar (GPR) antennas is crucial to the performance of GPR systems. Simple antennas have been characterized by analyzing their radiation patterns and directivity. However, there have been limited studies that combine real GPR antennas with realistic environments, which is essential to capture the complex interactions between the antenna and surroundings. We have investigated the radiation characteristics and sensitivity of a GPR antenna in a range of lossy dielectric environments using both physical measurements and a three-dimensional (3-D) ?nite-difference time-domain (FDTD) model. Experimental data were from measured responses of a target positioned at intervals on the circumference of a circle surrounding the H-plane of the antenna. A series of oil-in-water emulsions as well as tap water were used to simulate homogeneous materials with different permittivities and with complex conductivities. Numerical radiation patterns were created utilizing a detailed 3-D FDTD model of the antenna. Good correlation was shown between the experimental results and modeled data with respect to the strength of the main lobe within the critical angle window. However, there are discrepancies in the strength of main lobe at shallow angles. In all the dielectrics, the main lobes are generally broad due to the near-?eld observation distance but, as expected, become narrower with increasing permittivity. These results provide con?dence for further use of the FDTD antenna model to investigate scenarios such as larger observation distances and heterogeneous environments that are dif?cult to study experimentally.
关键词： electromagnetic modeling,Antenna measurements,?nite-difference time-domain (FDTD),antenna radiation patterns,broadband antennas
更新于2025-09-23 15:21:01
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Tri-Focal Configuration of Three-Dimensional Metallic Waveguide-Array Lens Antennas of Rotman Lens Concept for Multi-Beam Applications
摘要： This paper presents a design methodology of three-dimensional (3-D) passive metallic waveguide-array lens antenna (MWALA) by implementing the Rotman lens concept (RLC) for collinear multi-beam radiations on the same angular plane. The RLC methodology extends the original concept of two-dimensional (2-D) tri-focal Rotman lens into a 3-D one in free space. Thus, the MWALA has a planar aperture facing to the radiation boresight to resemble a planar phased array of waveguide antennas and also has a curved focal surface pro?le (CFSP) on the opposite side to receive the illumination by the radiations of feed antennas. The three co-planar focal points are speci?ed to de?ne a circular focal arc (CFA) for multiple feed placement to radiate multi-beams through this MWALA. The boundary formed by the CFSP and CFA resembles the shape of Rotman lens equivalently realized in free space. In addition, the shortage of freedoms in conventional MWALA design limited to dual-focus con?gurations and resulting in narrow scan angles, is relaxed by adopting the phase velocities inside the waveguides as an additional freedom to realize a tri-focal con?guration and broaden the scan angles of multi-beam radiation. Theoretical foundation and design guidelines are summarized with numerical and experimental examples presented to validate the feasibility.
关键词： Antenna radiation,Rotman lens,multi-beam radiation,waveguide array lens antenna
更新于2025-09-19 17:13:59
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[IEEE 2019 Photonics & Electromagnetics Research Symposium - Fall (PIERS - Fall) - Xiamen, China (2019.12.17-2019.12.20)] 2019 Photonics & Electromagnetics Research Symposium - Fall (PIERS - Fall) - Realization of Low-loss Epsilon-near-zero Properties Using PT-symmetric Metasurfaces
摘要： A circularly polarized patch antenna for future fifth-generation mobile phones is presented in this paper. Miniaturization and beamwidth enhancement of a patch antenna are the two main areas to be discussed. By folding the edge of the radiating patch with loading slots, the size of the patch antenna is 44.8% smaller than a conventional half wavelength patch, which allows it to be accommodated inside handsets easily. Wide beamwidth is obtained by surrounding the patch with a dielectric substrate and supporting the antenna by a metallic block. A measured half power beamwidth of 124? is achieved. The impedance bandwidth of the antenna is over 10%, and the 3-dB axial ratio bandwidth is 3.05%. The proposed antenna covers a wide elevation angle and complete azimuth range. A parametric study of the effect of the metallic block and the surrounding dielectric substrate on the gain at a low elevation angle and the axial ratio of the proposed antenna are presented.
关键词： microstrip patch antennas,Antenna radiation patterns,satellite antennas,size reduction,beamwidth enhancement
更新于2025-09-19 17:13:59
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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) - Design and Performance Analysis of an UWB Patch Antenna with Enhanced Bandwidth Characteristics
摘要： This paper presents a monopole ultra-wideband (UWB) patch antenna with enhanced bandwidth performance. The reference antenna has a square radiator and fed by a microstrip feed line. The other side of the substrate has a partial ground plane. A trapezoidal slot configuration with proper dimension has been inserted to upper edge of the partial ground plane under the feed line to modify the reference antenna bandwidth characteristics. Additionally, two rectangular shapes have been cut from the edge of the square patch to add another bandwidth improvement. The simulation results prove that the antenna fractional bandwidth of the reference antenna is 122.49 % while for the final antenna model is 147.28 %. The antenna maximum gain, radiation characteristics, radiation efficiency, and group delay characteristics are also investigated.
关键词： monopole antenna,radiation patterns,impedance bandwidth,ultra-wideband
更新于2025-09-04 15:30:14