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The efficient calculation of the electromagnetic interactions with dielectric objects is always a challenge to CEM (computational electromagnetics). Among the numerical exact methods, the method of moment (MoM) is considered to be more preferable than finite element method (FEM) and finite difference method (FDTD) for its high precision and discretization on the geometry model instead of the field...
For convenient portability mobile devices need to be small. To reduce their size, a small antenna is strongly required because the antenna is one of a mobile device's largest components. In addition, the antenna's bandwidth needs to be wide because the recent development of many kinds of multimedia services requires a large bandwidth. Designing a small antenna with a wide bandwidth is not easy, however,...
Using an equivalent circuit, a new wideband array was examined using physically realizable tightly coupled dipoles. A miniaturized element using inductive and capacitive loading was used to suppress ground plane effects for a broadband conformal array. Serial inductance was demonstrated to effectively miniaturize the radiating element and lead to even greater bandwidth as compared to the CSA array...
In this paper, a cross-type parasitic array antenna is designed to tune the radiation pattern which attenuates incoming interference and improve packet reception. Using only a 5-element planar array allows full 2-dimensional beam steering. The measurement shows that approximately 30 degrees of beam steering can be achieved by terminating parasitic elements with commercial Si-based varactors allowing...
A wideband planar monopole antenna with four-elements L-shaped slots on the ground plane is proposed and fabricated. The bandwidth of the antenna is 180 MHz (75 %) at 2.4 GHz and it shows a dipole-like radiation pattern with a high efficiency. It can be applied to ISM frequency band wireless communication system.
In this paper, two printed multiband fractal monopole antennas using the 1st and 2nd iteration of Minkowski Island geometry are proposed for WLAN communications. The monopole antennas have compact size of 28 times 18 mm2 and 21.5 times 18 mm2, respectively. The proposed antennas with different sizes of the ground plane have also been studied through numerical simulations in Ansoft HFSS. It is found...
A coplanar wave guide (CPW) fed semicircular slot antenna (SSA) with step impedance transformer is presented. Omni-directional radiation pattern in whole band with theoretical gain of 3 dBi with variation of plusmn0.5 dB is achieved. It has shown that this design of SSA gives experimental bandwidth of 10.7 GHz for VSWR < 2. Present results show suitability of structure for UWB communication.
Anisotropic films provide a means to achieve optical circuit elements that are relatively independent of incident angle. This observation opens up a variety of circuit synthesis methods for implementing optical devices with important properties. We showed filter and anti-reflection coating examples for TM polarization that are robust to variation in the angle of incidence. Duality would lead to equivalent...
In this work, the sequential code developed is effectively parallelized using the MPI. All objects are 2D perfect electric conductors (PEC) immersed in air. The illuminating waves are transverse magnetic (TM) plane waves where the electric field is parallel to the axes of the cylinders. The objective is to retrieve the number of scattering objects, their shapes and locations in few minutes versus...
A measurement method for verifying final conjugate match condition of assembled RFID tag is proposed in this paper. The verification results and maximum read range test results are all in good agreement. The verification method can be used to make sure whether the assembled RFID tag is in good match condition or not. In the future work, we will study how to use the verification method to find the...
In this paper, few topics related to the near-field and far-field behavior of a vertically oriented antenna above a PEC ground plane is discussed. The very near-field is determined by the position where the wave impedance approaches free space impedance, and the phase of the wave impedance approaches zero. As one move further ahead the wave sphericity condition determines the transition from the radiative...
A detailed analysis of the electric field integral equation (EFIE) at low frequencies is presented which is based on the Sobolev space mapping properties of the EFIE. The theory shows that in the low-frequency regime an EFIE with a logarithmic condition number growth can be obtained. This, provided that both the solenoidal and non-solenoidal parts of the EFIE are properly regularized. The regularization...
The Expanded Very Large Array (EVLA) project is currently under way to upgrade the Very Large Array (VLA) to improve the sensitivity, bandwidth, spectral resolution and frequency coverage of the existing array of 27 radio telescopes. The EVLA receivers will provide continuous frequency coverage from 1 GHz to 50 GHz. Three of the cryogenically cooled EVLA receivers will provide octave band coverage...
The method proposed by the authors to reduce the computational cost devoted to solve the full EM problem in such arrays is based in the macro basis function technique and the interpolation method. On the other hand, it is shown how the embedded element pattern convergence within a radius of influence allows us to account only for a few tens of significative elements when computing the aforementioned...
Antennas which are physically smaller than their operative wavelength are defined as electrically small antennas. An electrically small antenna characterizes any antenna which fits insides a sphere with radius a =1/k, where k is the wave number of the radiated or received field. Compact-size and wide-frequency bandwidth are in contradiction with lossless antennas. Based on the fundamental limits theory,...
This paper presents a study of the characteristic impedance of a ridge gap waveguide. Ridge gap waveguides belongs to a new metamaterial-based waveguide technology for millimeter and submillimeter waves which emerged recently. A formula for the characteristic impedance of an ideal PEC-over-PMC ridge gap waveguide has been derived. A preliminary numerical study of the characteristic impedance of a...
Method of moments (MoM) is a powerful numerical tool for solving integral equation (IE) formulations of the boundary value problems in electromagnetics. The widely used low-order (LO) vector basis functions often require dense geometrical discretization to achieve sufficiently good accuracies. Great reduction of the number of unknowns for a given problem and desired accuracy is achievable through...
Vias can introduce impedance discontinuity, slow down signal edge rate, add jitter and reduce eye openings, and cause data misinterpretation by the receiver in high-speed channel. This paper presents the design and optimization of differential vias for high-speed serial ATA connection at the data rate of 6 Gb/s. First, differential vias on a specific stackup were modeled in the 3D full-wave solver...
In this paper an analytical approach based on generalized cavity model and segmentation method has been proposed to investigate the wideband behavior of the probe-fed, U-Slot microstrip patch antenna. Contour integration methods to improve the overall convergence of the analysis has been demonstrated. Numerical results on convergence will be presented at the time of the conference.
The world-wide frequency band for passive UHF RFID is 860 to 960 MHz, or 11% bandwidth, and microstrip antennas [2] offer high gain, inexpensive manufacture, and with suitable ground plane independence from the object to which it is attached. Unfortunately, they tend to suffer from a narrow bandwidth. In this paper, we present a theory and implementation of a simple planar, wideband microstrip antenna...
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