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In 2004 TICRA released the new version of GRASP, GRASP9. A lot of new features have been added to those present in the predecessor, GRASP8. Two of those features, analysis of gaps in reflector surfaces and parallel processing, will be described in this paper.
Wideband top-loaded monopole antenna on a dialectric substrate was proposed, and design method using the decomposed model was presented in this paper. Parameter study to assist the antenna design was also carried out by using the MoM calculation.
A full set of numerical wave number k that includes imaginary part as function of frequency can now be obtained by a simple procedure which does not involve numerical root-finding scheme. FFT computation and data storage for the entire time sequence of all fields along the grids can also be avoided by approximating frequency domain inverse transform. The results of the initial numerical simulation...
We evaluate the relative influence of mutual coupling and of spatial correlation of fields on MIMO channel capacity, in the case of circular arrays of monopoles. For this purpose, we introduce several real and artificial configurations of the arrays, and study the influence of the array size and of the load impedance. It appears clearly that coupling generally enhance capacities for compact arrays,...
Summarizing, by using the MAR/MAP it is possible to overcome many difficulties encountered in conventional MoM treatments. Theoretical merits of the MAR are numerous: exact solution existence is established, convergence is guaranteed, and rigorous asymptotic formulas can be derived. Computationally, the MAR results in a small matrix size for a practical accuracy, and sometimes no numerical integrations...
The integration between NEC2 and Matlab created an environment similar to the environment an actual array would operate in by accounting for mutual coupling between the array elements. Changing the elements type to more directive elements enhanced the MSE performance in all cases. The 5-element linear λ/2 dipole array possessed a very poor performance when the incident signals where 2° apart whereas...
This paper refers to a special type of antenna, called frequency independent antenna, used in Stepped Frequency Continuous Wave (SFCW) radar employed for humanitarian demining. The radar transmits 128 frequencies within the frequency range from 400 MHz to 4845 GHz, in groups of 8 simultaneously transmitted frequencies. It has been built at the International Research Center for Telecommunications transmission...
A new methodology for robust imaging of permittivity profiles in 1D inhomogeneous media is proposed. The image reconstruction technique makes use of non-local orthogonal basis functions that span the entire remote image region. The linearized integral equation is weighted at different frequencies which yields a diagonally dominant matrix due to the orthogonality of the kernel and the specially selected...
A reflective spatial power combiner employing the tile architecture is presented. This spatial power combiner is to be used as part of a dual-reflector transmitting antenna intended for uplink satellite communications at Ka band. A modular array composed of 37 elements is to be fabricated and intended to provide more than 20 W of output power with a combining efficiency of 58%.
A corrugated horn for the Parkes radio telescope has been optimized to cover the 16–26 GHz band and to provide an efficient illumination of the reflector. Two additional horn to cover the narrower 20–24 GHz and 21.6–22.1 GHz bands have also been designed. The 20–24 GHz and 21.6– 22.1 GHz horns display better G/Tsystem performance as demonstrated by Fig. 7. As the three horns are highly optimised,...
A powerful optimization procedure of substrate lens antennas has been proposed at millimeter wave frequencies. Compared to previous works, this approach is global and thus does not require the a priori knowledge of an initial lens profile computed with conventional GO-based synthesis techniques. Our design methodology combines a genetic algorithm with an efficient asymptotic analysis of the radiation...
After the first free space experimental scattering database success, we have decided to continue our exertions to increase the number of targets and to vary their characteristics. The first effort was to rebuild all the communication and control software to get a better synchronisation of all the different mechanical movements with the network analyser. Second, we had to replace the object support...
This paper propose a CPW-fed, quad-band, compact, lightweight and low-cost printed antenna suitable for multi-band wireless local area networks (WLAN). The antenna is printed on a thin substrate, has a very small area and is fed by a co-planar waveguide line, which can be directly connected with the associated microwave circuits on the same substrate. The computed and measured results for 2.4, 4.9,...
We have presented the design of the antenna filter multi-function using a methodology based on a direct synthesis of the filtering functions and taking into account the electromagnetic constraints. We have showed that we could design either the radiant filter function or the filtering antenna function. From these results we have designed a structure with multi-mode cavities in order to make the filtering...
Classical and modern navigation, landing and radar systems rely on the radio transmission and reception. Relevant objects in the radiation field can harm the intended characteristics of these systems. Modern state-of-the-art simulations can predict the electrical performance in the presence of these objects. Countermeasures can be designed from this knowledge in an increasing number of complicated...
The short-circuited line method or Roberts-Von Hipple's method for dielectric characterization is usually not found on the bibliography, maybe due to its implementation requires the resolution of a transcendental equation on the complex plane that yields infinite solutions being then necessary to suppress the ambiguity. In this paper, this technique is automated using a vectorial network analyzer...
Based on the relationship between the potential and its normal derivative on the boundary of the region of interest, the solution of the Dirichlet and the Neumann boundary value problems relative to the Laplacian is written explicitly in an operator form. The numerical computation of the potential for regions of arbitrary shape is performed by converting the two boundary operators involved into square...
A broadband antenna has been coupled to a planar Schottky diode for the realisation of a sensitive power detector for mm-wave frequencies. The measured response curve is in agreement with calculations and shows values of up to 3000 V/W. However, further work has to concentrate on the accuracy of the sensitivity and the reduction of ripples in the frequency response. Also higher frequencies are targeted...
The accurate 2-d model of radiation of the electric modes of a PDW on finite number of rectangular grooves cut out on the surface of the perfectly conductive screen have been built for the first time.
A major restriction of high gain microstrip antenna arrays is found in their high losses, mainly due to the feeding network. In this contribution, design and results of a 24GHz microstrip array antenna with low loss, low cost and low profile NRD-guide feeding network are presented. Interconects between planar structures and NRD-guide feeding network are done by slot coupling. The feeding network for...
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