Antennas - Microwave Engineering - Computational Electromagnetics - Metamaterials - UWB Communications Research Papers (original) (raw)

In this paper, the axial-mode performance features of a non-uniform helix, whose non-uniformity is defined by a logarithmic variation of turns spacing along its axis, is presented. Using the classical vector potential approach, the paper rigorously formulates radiation-zone field integrals for the antenna in terms of an unknown distribution of current. Because the formulation derives from a comprehensive analytical description of this 'log-helix' antenna's geometry, the unknown current distribution is readily determined with the use of the circuitgeometric properties of the Method of Moments (MoM). Subsequently, computational results reveal that-as obtained with other non-uniform helical antennas-the 'log-helix' antenna performs significantly better than the corresponding uniform helical antenna of identical axial length. As examples, a 39% increase in power gain was recorded for the log-helix over the corresponding uniform helix; whilst a 25% improvement in radiation field's axial ratio was achieved. In addition to far-zone fields and their associated performance metrics, antenna input parameters are also computed and discussed in details in this paper. Outcomes of a comparison of the performance of the log-helix with that of an exponential helix of about the same axial profile suggest that whereas the latter has a better power gain performance, the former is superior in terms of axial ratio bandwidth performance.

- by and +1
- •
- Electrical Engineering, Communication, Antennas, Antennas & Radio Wave Propagation

Fundamentals of Electrostatics

- by Dhivya Manian
- •
- Field Theory, Electromagnetics, Electromagnetic Theory, Emf

This paper presents a negative index metamaterial incorporated UWB antenna with an integration of complementary SRR (split-ring resonator) and CLS (capacitive loaded strip) unit cells for microwave imaging sensor applications. This metamaterial UWB antenna sensor consists of four unit cells along one axis, where each unit cell incorporates a complementary SRR and CLS pair. This integration enables a design layout that allows both a negative value of permittivity and a negative value of permeability simultaneous, resulting in a durable negative index to enhance the antenna sensor performance for microwave imaging sensor applications. The proposed MTM antenna sensor was designed and fabricated on an FR4 substrate having a thickness of 1.6 mm and a dielectric constant of 4.6. The electrical dimensions of this antenna sensor are 0.20 λ × 0.29 λ at a lower frequency of 3.1 GHz. This antenna sensor achieves a 131.5% bandwidth (VSWR < 2) covering the frequency bands from 3.1 GHz to more than 15 GHz with a maximum gain of 6.57 dBi. High fidelity factor and gain, smooth surface-current distribution and nearly omni-directional radiation patterns with low cross-polarization confirm that the proposed negative index UWB antenna is a promising entrant in the field of microwave imaging sensors.

An efficient, small, planar antenna is
proposed using DNG (Double Negative) metamaterial. The
double negative property is being obtained by introducing
unit cell structure. A unit cell consists of microstrip gaps
and vias, whose behavior is equivalent to the combination
of series capacitors and shunt inductors respectively. The
via leads to negative permittivity and microstrip gap leads
to negative permeability. The meta structure is used
because, metamaterial enhances antenna properties as well
as a high degree of miniaturization is possible as average
cell size of metamaterial is less than a quarter of the guided
wavelength. As a high radiation, impedance matching, gain
and compactness can be achieved by the proposed antenna,
it is very useful for wirelessly access network resources at
home and elsewhere. Especially for downwardly
compatible IEEE 802.11g wireless-fidelity (Wi-Fi) at 5
GHz. Using this metamaterial antenna the demerits of
ordinary patch antenna like low gain and efficiency can be
overcome

The wireless nanosensor network paradigm has seen a dramatic increase over the last decade. The envisioned concept uses the integrated machines (devices) at the nano-scale level. Those devices interact on a cooperative basis by means of principles known in wireless communication networks. Today, the design of the protocol stack for wireless nanosensor networks represents the crucial issue to be addressed. Currently available tools only support molecular-based approaches without the ability to account for the relevant impact that electromagnetic communications may have in this field. To cover this white spot, in this paper, the theoretical comparison of available simulation tools is given. Further, we focus on the Nano-Sim tool and create the scenario for wireless sensor networks (WNSN) based on electromagnetic communication in terahertz band.

This paper presents the implementation ofan Impulse Radio Ultra Wide Band (IR-UWB) communication system based on Orthogonal Amplitude Modulation (OAM) on the FPGA board (Field ProgrammableGate Array). The Orthogonal Amplitude Modulationis a new modulation technique that provides a highdata rate transmission, using the orthogonal waveforms named MGF (ModifiedGegenbaeur Function).In this work, the FPGA card and the converters DAC(Digital-to-Analog Converter) and ADC (Analog to Digital Converter) are considered to perform the implementation. The system is running in the simulation field andin the real system on the hardware equipment.The obtained results show that the implementation ofUWB-OAM system on FPGA board is running well andprovide a high-real time computations system.

To Oversee the research on precipitation a portable, compact Frequency Modulated Continuous Wave (FM-CW) System said as the Micro Rain Radar (MRR or MRR2) is used which operates at 24 GHz. It's a low-cost, often radar system that requires minimum maintenance and supervision. In this paper we derive and compare the Z-R relations from a low-power, low-cost vertically pointing FM-CW System Micro Rain Radar (MRR) operating at 24.1 GHz at different rain fall events. Here the rainfall data is recorded continuously by a vertical profile Doppler radar Micro Rain Radar MRR2. Z-R relation of the form Z = A R b is derived from coastal location of Andhra Pradesh of Cyclone period Rain events, clear-sky mode and monsoon period rain events are collected from the vertically profiling Doppler radar Micro Rain Radar (MRR2) installed at K L University (16.440N, 80.620E) 29 meters above the sea level (ASL) in Centre for Applied Research in Electromagnetics (CARE) lab. The coefficients A and b of Z-R relation varies from place to place. Data recordings collected under different climatic condition like clear sky, monsoon and cyclone are evaluated and sketched. By this seasonal rainfall and reflectivity intensities with variations in coefficient A and exponent b is observed.

Se propone que el Ayuntamiento de Othón P. Blanco,, como medida precautaria, a efecto de evitar riesgos riesgos en materia de salud individual-familiar y pública, bienestar ciudadano, derechos humanos individuales y colectivos, niveles de protección civil, y preservación de medio ambiente; promulgue normativa en materia de construcción de torres ó antenas de telefonía celular

In this contribution, we investigate the possibility to apply the mantle cloaking technique to radiation platforms consisting of a combination of different antenna types. More specifically, we consider the challenging case of a half-wavelength dipole working in close electrical proximity to an Archimedean spiral slot antenna. We show that by covering the dipole with a suitable cloaking metasurface, it is possible to significantly reduce its blockage on the Archimedean antenna and make it work as if it were isolated. We also show that the same system can be engineered to exploit the aperture antenna as a reflector for the dipole that, thus, can operate as a standard sector antenna. This cloaking application is confirmed by realistic full-wave numerical simulations.