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The size reduction for resonant monopoles is an important issue for HF and VHF antennas. Unfortunately, size reduction results in degradation in both efficiency and bandwidth, as is well known from the fundamental limits on small antennas. This paper firstly introduces a MATLAB-controlled NEC2 simulation tool with genetic algorithm optimization, and uses this to find the optimal position of inductors...
Plasmon resonances are able to produce a large field enhancement, which can be exploited for various purposes, such as biosensing or optical mixing. In this paper, the plasmon resonance of two stacked gold nanodisks separated by a tiny 2 nm gap is studied in time-domain simulations, offering the possibility of transient and broadband analysis. Moreover, time-domain simulations are amenable to extensions...
This paper continues the discussion of the design of an antenna with collinear electric- and magnetic-dipole moments out of phase by approximately π/2 (90°). Using a high-Q approximation, a switched oscillator is matched to the antenna for radiating an oscillatory pulse.
A simple square loop printed antenna fed by a coplanar waveguide (CPW) is proposed. Considering a return loss criterion of better than 9.5 dB, the antenna operates in two frequency bands: 1.73-2.50 GHz and 3.44-3.87 GHz. These bands represent 36.4% and 11.8% impedance bandwidths respectively. A parametric study has also been carried out by varying the spacing between the ground and the square loop...
In this paper, the varactor-loaded open-ring microstrip antenna is proposed. To overcome the inherent characteristics of narrow bandwidth of the open-ring microstrip antenna, the varactor is positioned on the edge of the ring. The frequency is tuned by controlling the DC voltage connected to the varactor. For the simulation model, instead of the real varactor, the discrete capacitor is used. The return...
The cylindrical cavity resonator method is presented to evaluate the complex relative permittivity of lossy materials. The loaded sample in the cavity is required to have the rotational symmetry but may have bulky and/or wide sample. To measure the sample at the specified frequency with high Q, movable dielectric supports with low permittivity and low loss are loaded in cavity. Theoretical basis of...
A carbon nanotube (CNT) half-wavelength resonator is designed and analyzed in this paper. The electrical characteristics of the resonator are predicted based on the equivalent circuit model of multi-walled CNT (MWCNT). The propagation behavior in the resonator is presented with the influence of MWCNT diameter and operating frequency taken into account. The Q-factors for different kinds of losses in...
This paper proposes a method that combines a data-independent beamformer with Matrix Pencil (MP) method to take into consideration the morphological properties of the malignant tissue. The simulated results have shown the resonant frequency and damping factor of complex natural resonance (CNR) are capable of differentiating the malignant tissue from other significant interferers such as benign lesions...
A novel multi-frequency printed quadrifilar helix antenna based on Multiple arm technique is presented in this paper. Double frequency and satisfactory antenna characteristics are achieved. The antenna has relatively compact size and hemispherical pattern with excellent circularly polarized coverage. The antenna is designed and simulated with the application of HFSS software. The simulation results...
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