A New Wideband Circularly Polarized Dielectric Resonator Antenna Loaded with Strips

This paper proposes a novel wideband circularly polarized (CP) dielectric resonator antenna (DRA) loaded with strips. The CP DRA comprises a circular DR, two pairs of driven L-like DR strips with different lengths, and a square ground-plane. To couple the electromagnetic energy to circular DR, an orthogonal cross-slot is used, and a stepped microstrip-line is also used to adjust the impedance matching. Influenced by the concept of deformed DR, two pairs of L-like DR strips of different lengths are inserted into the circular DR as part of the driven element to excite a new axial ratio (AR) resonant point. An antenna prototype is simulated, manufactured, and measured to validate the unique design. The measured results show that the designed antenna has broadband characteristic with a −10 dB IBW of 54% (1.91–3.32 GHz) and 3 dB ARBW of 42.1% (2.10–3.22 GHz).

Resonant multilead point-contact tunneling: Boundary state formulation

In this paper, we study a model of resonant multilead point-contact tunneling by using the boundary state formulation. At a critical point, the model is described by multiflavor chiral fermions on an infinite line with a point contact interaction at the origin. By applying the folding procedure, previously developed for the model of resonant point-contact tunneling of a single lead, we map the model onto a nonchiral fermion model defined on the half line. The resonant point-contact tunneling interaction is transcribed into a nonlocal effective boundary interaction in the folded setup, where the boundary state formulation is applicable. We construct the boundary states for the models with two and three leads explicitly and evaluate the correlation functions of currents operators exactly. The electron transport between the leads is dominated by the resonant point-contact tunneling in the low frequency regime. We observe some [Formula: see text] and [Formula: see text] group theoretical structures, which may be useful to analyze more complex models.

Chiral Fermion and boundary state formulation: Resonant point-contact tunneling

We study a model of resonant point-contact tunneling of a single Luttinger-liquid lead, using the boundary state formulation. The model is described by a single chiral Fermion in one-dimensional space with one point contact interaction at the origin. It is the simplest model of this type. By folding the infinite line, we map the model onto a nonchiral model on the half infinite line and transcribe the point-contact tunneling interaction into a boundary interaction. The tunneling interaction yields a nonlocal effective action at the boundary. We explicitly construct the boundary state and evaluate the current correlation functions. The contact interaction is shown to act on the lower frequency modes more strongly.

Optimization Design and Performance of Vibration Suppression for Delayed Dynamical Vibration Absorber with Broadband

The delayed dynamical vibration absorber is applied to suppress the vibration of the torsional vibration system. The governing equations of the two degree of freedom vibrating system consisting of crankshaft and delayed dynamical vibration absorber are obtained. The physical parameters of the dynamical vibration absorber for the passive control system are optimum designed. The frequency of anti-resonant point is located at the midpoint between two resonant points, and the optimized amplitude frequency response curve is relatively flat near the anti-resonant point. The control parameters of gain and time delay are optimum designed in the active control system. The minimum amplitude of crankshaft is selected as the optimization objective. The genetic algorithm is used to optimize these control parameters. The optimized delayed dynamical vibration absorber has achieved good performance of vibration suppression within a wide frequency band of external excitation.