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Linear embedding via Green's operators (LEGO) is a computational method in which the multiple scattering between adjacent objects - forming a large composite structure - is determined through the interaction of simple-shaped building domains, whose electromagnetic (EM) behavior is accounted for by means of scattering operators. This method has been successfully demonstrated for 2-D electromagnetic...
In this paper, we presented a compact directive UWB transmit receive antenna pair. The basic operation of the antenna was discussed and the effect of the dimensions on the bandwidth, pattern and isolation performance was investigated. The antenna was fabricated and measured. The measurement and simulation results showed good agreement. The measured isolation was better than 21 dB and the measured...
Dielectric covered antennas have been extensible used in microwaves. They are usually designed with dielectric quarter wavelength super-layers or with frequency selective surfaces. The main drawback of these antennas is that their BW is inversely proportional to the directivity. The new geometry proposed here makes use of a silicon lens instead of dielectric super-layer. In this case, the directivity...
This work demonstrates single-frequency conditions on the constitutive dyads of a bianisotropic linear metamaterial that are sufficient to ensure cloaking for arbitrary shapes and arbitrary illumination. These cloaking conditions are formulated in terms of non-radiating volumetric currents, which are also useful in designing new metamaterial cloaks. The special known cases of transformation optics...
This paper presents an efficient, 3-D alternating-direction-implicit finite-difference time-domain (ADI-FDTD) method for modeling wave propagation in Debye dispersive media. The efficient algorithm features a simpler, matrix-operator-free right hand side than the conventional ADI-FDTD method which results in substantial reduction of floating point operations (flops) counts and memory indexing. Formulation...
A practical design guidance of a wide band shielded GPR antenna is discussed. The designed antenna is used in a GPR system working at 400 MHz center frequency. Measured data show that with properly designed shielding and absorbing materials, the bow-tie antenna with shield performs as desired. Besides antenna design, the key issues in a shielded GPR antenna design are the depth of the shield box and...
The analysis of sub-wavelength profile high-gain planar antennas employing two periodic surfaces (AMC and PRS) has been presented using periodic spectral-domain MoM. Three different cavity antenna designs consisting of a grounded 2-D infinite array of metal patches and a superimposed infinite PRS array have been proposed in order to validate the technique. The thickness of the cavity for the three...
With the proposed scheme, the size of a microstrip antenna can be reduced as much as desired. However the antenna efficiency as well as the bandwidth will be lowered because of the reduced aperture area, which will be communicated further in the future.
In this work, we have used the opened waveguide cavity to enhance the isolation. The proposed reflector with the donor and receptor antenna satisfied the isolation, more than 80 dB as well as the gain and return loss of the antennas. Also the size of the reflector is reduced considerably compared with conventional reflectors.
A new highly sensitive radio frequency pressure transducer has been designed to operate in the millimeter wave frequency range that can be seamlessly integrated with other RF circuits in the LTCC multilayer packaging technology. The resonator consists of a stacked-patch based on LTCC multilayer packaging technology, having an air cavity embedded by a silicon (Si) diaphragm that deflects due to pressure...
The "Wheeler Cap" can be used to determine the radiation efficiency of electrically small antennas very accurately. The purpose of this paper is to simulate the improved Wheeler Cap measurement method with a Vivaldi antenna. The WIPL-D simulation tool is used to simulate the antenna in free space and in the Cap. This process can be used to test the accuracy of the improved Wheeler Cap method...
In this paper, a trough leaky-wave antenna is considered that was inspired by the half-width microstrip leaky-wave. The TLW antenna is naturally suitable for flush-mount installation in a metallic body such as an automobile. The radiation characteristics will be investigated in more detail such as the design of the matching cavities and their effect on the upper half-space radiation pattern as well...
In this paper we present a novel design for a low-profile Fabry-Perot (FP) cavity type antenna, which achieves a high directivity combined with an excellent aperture efficiency. Unlike similar FP cavity-type antennas, that are excited with either a dipole or a microstrip patch antenna (MPA), the proposed approach utilizes a slot feed, which not only is easier to fabricate than the presently available...
In this paper, an LTCC cavity backed array antenna in order to improve the radiation efficiency and bandwidth is proposed. LTCC cavity consists of several ground planes and dielectric layers with closely spaced metallic vias connected. It is shown that the size of an LTCC cavity has the effects on the performances of radiation and bandwidth for the antenna. This design is applied to Ferro A6 LTCC...
Presented here is a design for an all-metal ultra-wideband antenna element that can achieve bandwidth of 12:1. While the design itself is worth reporting in its own right, this array element was designed as part of a study on low-cost ultra- wide bandwidth arrays reported here. For more robust design validations, finite array simulations will also be performed to mimic the set of S-parameters collected...
A simple method is proposed for obtaining a partially reflective surface with increasing reflection phase for use in wideband, low-profile electromagnetic band-gap resonator antennas. Using the proposed types of partially reflective surfaces and a perfect electric conductor ground, a wideband resonant cavity can be formed and hence a wideband resonant cavity antenna can be designed. The method to...
A method is presented for increasing the efficiency of integral equation solutions of cylindrical monopole antennas. This method can be used to replace effect of a coupled integral equation with a 2-port network. The numerical results are consistent with expectations. This numerical model and its use are to be validated with measurements.
Dual-Ridged Horn Antenna (DRHA) are a workhorse in EMC and antenna pattern measurement laboratories. Their broadband capability allows the user to test over a wide frequency ranges without the need to stop the test to change antennas. Recently these antennas came under scrutiny when Burns et al. showed the pattern problems at the upper end of their band. Since their work new models have been introduced...
The numerical examples show, that, the proposed EDD algorithm has a better accuracy and, computationally, it is much less costly, than the domain decomposition MoM scheme. We are currently working on extending the method to 3D configurations, and to the multi-frequency ultra-wideband (UWB) regime.
In this paper, we have developed additional basis functions for inhomogenous domains. The basis functions satisfy all the boundary condition requirements. These basis functions are defined on each subdomain and tested using hexahedral elements but they can be readily generalized to any linear subdomains. This enables us to use available meshing structures such that any material discontinuity in PU...
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