In antenna design, feeding structures may cause improper effects on the performance of antennas. In this paper, a practical and efficient feeding structure for differential elliptical antennas using the combination of...
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A novel quad-band coplanar waveguide (CPW)-fed stacked antenna suitable for wireless LAN applications is presented. The antenna uses two orthogonal-shaped slot antennas printed on similar groundless substrates stacked...
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A new 3D spherical ultra wideband antenna is presented in this paper. Achieving an acceptable return loss, the antenna geometry is modified to highly reduce the weight of the antenna.
A new 3D spherical ultra wideband antenna is presented in this paper. Achieving an acceptable return loss, the antenna geometry is modified to highly reduce the weight of the antenna.
The recent allocation of the 3.1-10.6 GHz frequency spectrums for ultra-wideband (UWB) applications has presented many opportunities and challenges for antenna designers. Patch antennas are extensively used in wireles...
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ISBN:
(纸本)9781424408771;1424408776
The recent allocation of the 3.1-10.6 GHz frequency spectrums for ultra-wideband (UWB) applications has presented many opportunities and challenges for antenna designers. Patch antennas are extensively used in wireless communications because of their light weight, low cost, and ease of fabrication. These features are desirable for both indoor and outdoor handheld UWB antenna applications. Ideally, UWB antennas should be non-dispersive or dispersive in a controlled fashion that is amenable to compensation. In this paper, to avoid the feeding problems and also costly fabrication, we modified the shape of the elliptical antenna by bending edges and cutting metal sections appropriately. The antenna structural parameters are then optimized to improve its performance. To avoid using the balun transformer and also to improve the antenna dispersion characteristics, the complement structure of the antenna was considered which results in a dragonfly shape antenna. The designed antenna was fabricated and the simulation results have been verified by comparing with measurements.
A new planar UWB antenna with satisfactory return loss and dispersion characteristics based on printed circular disc monopole antenna is presented in this paper. Finally the designed antenna was fabricated and the sim...
A new planar UWB antenna with satisfactory return loss and dispersion characteristics based on printed circular disc monopole antenna is presented in this paper. Finally the designed antenna was fabricated and the simulation results have been verified by comparing with measurements.
We propose a new approach for reconstructing a three-dimensional object from a single two-dimensional freehand line drawing depicting it. A sketch is essentially a noisy projection of a 3D object onto an arbitrary 2D ...
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ISBN:
(纸本)9781450318235
We propose a new approach for reconstructing a three-dimensional object from a single two-dimensional freehand line drawing depicting it. A sketch is essentially a noisy projection of a 3D object onto an arbitrary 2D plane. Reconstruction is the inverse projection of the sketched geometry from two dimensions back into three dimensions. While humans can do this reverse-projection remarkably easily and almost without being aware of it, this process is mathematically indeterminate and is very difficult to emulate computationally. Here we propose that the ability of humans to perceive a previously unseen 3D object from a single sketch is based on simple 2D-3D geometrical correlations that are learned from visual experience. We demonstrate how a simple correlation system that is exposed to many object-sketch pairs eventually leams to perform the inverse projection successfully for unseen objects. Conversely, we show how the same correlation data can be used to gauge the understandability of synthetically generated projections of given 3D objects. Using these principles we demonstrate for the first time a completely automatic conversion of a single freehand sketch into a physical solid object. These results have implications for bidirectional human-computer communication of 3D graphic concepts, and might also shed light on the human visual system.
In this paper we studied the effects of external fields' polarization on the coupling of pure magnetic fields into human body. Finite Difference Time Domain (FDTD) method is used to calculate the current densities...
A novel quad-band coplanar waveguide (CPW)-fed stacked antenna suitable for wireless LAN applications is presented. The antenna uses two orthogonal-shaped slot antennas printed on similar groundless substrates stacked...
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A novel quad-band coplanar waveguide (CPW)-fed stacked antenna suitable for wireless LAN applications is presented. The antenna uses two orthogonal-shaped slot antennas printed on similar groundless substrates stacked at the top of each other. Each antenna is known to be suitable for dual-band operation, so the stacked configuration gives rise to the satisfactory operation of the antenna in four distinct frequency bands. The specifications of the antenna's operating frequency bands, i.e. the center frequencies and their respected band widths have been selected such that most high speed wireless LAN systems especially those with WiMAX protocol can be supported by the antenna. Ansof's HFSS software was employed for designing the antenna. The CST Microwave Studio was then used for verifying the results and optimizing the structure for the desired frequency bands.
A new approach to control system design has been implemented in the software described here. The set of controllers simultaneously satisfying multiple design specifications can be obtained without performing a traditi...
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Model checking can be used to verify temporal properties of hybrid automata. However, model checking is not decidable in general. We overcome this difficulty by considering a durational graph abstraction, for which mo...
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ISBN:
(纸本)9781424414970;1424414970
Model checking can be used to verify temporal properties of hybrid automata. However, model checking is not decidable in general. We overcome this difficulty by considering a durational graph abstraction, for which model checking is decidable. The contribution of this paper is to show that, given a hybrid automaton and the durational graph abstraction, there exists a simulation relation between the two systems. This approach allows checking properties such as safety, but also timing properties of hybrid automata. We apply our framework to a relevant case study in the context of air traffic management (ATM). For an extended version of this paper refer to [15].
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