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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...
Increasing consumer demand for additional and more capable wireless and high-speed data services has led to many new wideband and multiband communications devices. Multiple-input multiple-output (MIMO) antenna systems are one such technology that can increase data rates, provide robustness and reduce interference. However, mutual coupling issues can arise from having multiple antennas in compact and...
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...
A vertically folded dipole on a multi-layer circuit board is proposed. The two radiation arms are spread into two dielectric surfaces and connected through vias. It effectively reduces antenna area by half without decreasing the bandwidth. It also facilitates meandering the strip dipole and further reduces the antenna length. Examples are given to characterize the vertical two or three folded dipoles...
In this paper a wire inverted L-shape monopole antenna is considered as the source. This antenna is not matched when it is placed above a PEC ground plane. Using three different artificial magnetic conductor (AMC) ground planes the antenna is not only matched at the desired frequency but its input impedance bandwidth is also increased significantly. Effects of the ground plane size are also studied.
The possibility to realize artificial magnetic conductors using grounded uniaxial materials has been investigated. The results have been verified with numerical simulations for the TM polarization.
A novel technique to enlarge the absorption band of a high-impedance surface absorber has been proposed. The enlargement of the absorbtion band has been verified with numerical simulations.
In this paper, the use of a corrugated surface for miniaturizing a microstrip antenna is presented and discussed. In addition, its implementation using standard printed circuit board (PCB) fabrication techniques is presented. Microstrip antennas exhibit many desirable characteristics such as low-profile, low weight, conformability and ease of fabrication. Such characteristics are attractive for many...
This article introduces a new design technique for producing matched magneto-dielectric metamaterial slabs. The technique is based on a genetic algorithm for the optimization of thin metallo-dielectric metasurfaces. These metasurfaces comprise of a periodic array of electrically small unit cells and backed by a perfectly conducting ground plane. Examples are also presented to show the effectiveness...
In this paper, MLFMA is implemented in the IEFIE to compute scattering from complex conducting structure coated by thin dielectric material. Numerical results demonstrate the efficiency and validity of the present method.
In this paper, a printed leaky-wave antenna with a sinusoidally modulated surface reactance (SMRS) is reported. The TM polarized antenna consists of metallic strips with periodically varying gaps printed on a grounded dielectric substrate. The designed antenna radiates at thirty degrees from broadside at 10 GHz, and exhibits a gain of 14.7 dB. Theoretical, simulation, and experimental results are...
We introduced a new low-profile UWB monopole antenna to achieve overhorizon operation from low VHF frequencies up to 2 GHz. The curvature profile of proposed Inverted-Hat Antenna is logarithmically related to the distance from the feed point, and thus results in a frequency-independent performance. The eleven-ellipse IHA is the most frequency-independent design. Other outer surface growth profiles...
Calderon preconditioning is very succesful in stabilising the EFIE and the use of BC functions makes the formalism valid on open surfaces. Through applying a broadband fast multipole method, the complexity can be reduced from O (N2) to O(N log N), allowing the simulation of very large structures. In the high frequency case a localised version of the preconditioner must be used to avoid excessive scattering...
It has been demonstrated that two layer metamaterial Hilbert curve array constructed from low conductivity material can act as a thin wideband radar absorbing screen. The advantage of using Hilbert curve over traditional circuit analogue radar absorbing screen is the smaller unit cell size, resulting in reduced coupling to higher order Floquent modes and reduced diffraction effects, which in turn...
This paper suggests algorithms for maximizing the amount of power used for microwave heating . The first algorithm uses a phased array. This only regulates the magnitude and phase of each source for maximizing power at the target area of the object. The second one uses a buffer-layer. This has a matching effect by controlling the permittivity and thickness of the buffer layer. To verify top phantom...
A simple, low-profile, all-surface RFID tag has been proposed. The tag has been studied in its planar and conformal form to understand bending effects. The tag was placed on different surfaces and the performance of the tag was evaluated in detail. It has been shown that this tag is robust in different environments (surfaces) and can be used for various applications ranging from logistics to remote...
Novel horn antennas incorporating Sievenpiper high-impedance electromagnetic surfaces are shown in the following work to provide a reduction in volume. Functioning as TEM horn antennas, they operate at geometries that would otherwise be below the TEio cutoff frequency and are capable of carrying more power than microstrip antennas with equivalent volumes. Four antennas in two geometries with metal...
Moving platforms, like manned and unmanned aerial vehicles, require adaptable directive antennas for both communication and radar applications. The integration of these antennas into the body of the platform drives significant development time and expense, and in many cases adversely affects the overall vehicle performance by adversely affecting its aerodynamics or weight. Being able to integrate...
The simulation of radiation problems typically involves localized excitation of a small and refined portion of the mesh representing the antenna. Due to this fact and the implicit units imbalance of problems comprising wire and surface elements, the convergence of the iterative solutions often shows a bad behavior. In this work, a preconditioning scheme is presented which moderates the strong dominance...
In this study, we have derived the asymptotic solution for the ground wave propagation over the land-to-sea mixed-path by applying the aperture field method. We have assumed that both the transmitting and the receiving antennas are placed at the heights sufficiently larger than the wavelength. By comparing with the reference solution calculated numerically, the validity of the asymptotic solution...
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