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The center fed disk antenna is used for comparing between the known moment method (MM) solution based on expanding the surface current density Jρ (ρ) on the disk, and the proposed MM expansion of the field component Eρ (ρ) outside the disk, on the disk plane. It is shown that for R < λ, 3 current basis functions or 3 field basis functions are enough for excellent convergence of the solution. However,...
This work (this work was partially supported by FACEPE and CNPq) perform a full-wave analysis, using method of moments, to determine the mutual impedances of spherical microstrip patches. The patches are allowed a more general shape, following the spherical coordinates, as shown in Fig. 1. The effect of moving the patches (keeping the average widths) toward the z-axis will be discussed on both input...
For solving Bessel function's singular problem of Sommerfeld integral in calculating the spatial domain Green's function of cylindrically stratified media, a domain-division algorithm is proposed in this paper, which can realize the computation for all elements of Z-matrix in the method of moment. Then, arbitrary shape cylindrical conformal microstrip antenna (CCMA) fed by microstripline is theoretically...
An efficient method of moments approach for the analysis of arbitrarily shaped spherical antenna is presented, where the Rao-Wilton-Glisson triangular basis functions and the dyadic Green's functions have been employed. The computation efficiency has been enhanced further using an asymptotic extraction technique in conjunction with the mixed potential integral equation representation of the electric...
Three different slotted broadband single layer rectangular patch antennas having improved radiation patterns and gain are presented. A single I- shaped slot single layer rectangular patch antenna gives an impedance bandwidth (-10dB return loss) of 24.39% with an average gain of about 10.51 dBi over the entire passband and peak gain of 11.04 dBi. With double I- slot an impedance bandwidth (-10dB return...
A printed spherical helical wire antenna is modelled using the method of moments. The effects of the dielectric sphere permittivity on the antenna characteristics have been studied. Computed results have been validated against simulations using a commercial software package.
The recently developed method for the analysis of microstrip antennas on hemispherical structures has been applied to derive the input impedance characteristics of quasi-rectangular microstrip antennas. By using corresponding full-wave equivalent circuits, the dyadic Green's functions of this structure and the system equation for the tangential field components at the interfaces can be analytically...
Available closed-form Green's function (CFGF) representations for cylindrically stratified media are modified to obtain new CFGF representations that yield very accurate results for cases where source and field points are on the top of or very close to each other. Consequently, these new expressions can safely be used for the entries of the method of moments (MoM) impedance matrix that represent the...
We present in this work some theoretical and experimental results of utilization of loop parasitic elements in wire (dipole) and planar (patch and monopole) antennas for increasing the impedance matching bandwidth. The antennas were analyzed using our programs, based on the numerical resolution of the electric field integral equation (EFIE) by the method of moments (MoM), and using the commercial...
A probe-fed cylindrical microstrip antenna (CMA) is discussed. The excitation problem is solved by the method of moments in the spectral domain with the usage of sub-domain basis functions. An effective way is employed to improve convergence of the elements (right hand sides of the equation system) describing the excitation field. The return loss of a CMA with an E-shaped patch is presented.
This paper proposes a numeric procedure that enables the iterative design of the radial line pin-fed network included into the optimization loop. For reliable results of the pin's self impedance the end effect need to be considered, especially for the long pins. By including the end effect in the mutual impedance calculation the accuracy of the results may be further improved. The theoretical analysis...
Microstrip Antennas (MSAs) consist of a metallic radiating patch on one side of thin dielectric substrate and other side is ground plane. Most important advantages of MSAs are low profile, light weight and compatibility with integrated circuit technology. MSAs are used in mobile communication, satellite communication, radar, direct broadcasting, global positioning systems and remote sensing. The major...
The major limitations of microstrip antennas (MSAs) are their narrow impedance bandwidth, small gain and low power handling capability. A half U-slot MSA with shorting wall has been designed and experimentally verified. Its center frequency is observed at 2.66 GHz. The bandwidth is 688 MHz and percentage bandwidth is 25.6% has been obtained while radiation efficiency is above 94% for the operating...
In this paper, the design of a compact planar bandpass filter above a defected ground plane is presented. The filter is designed as a combination of microstrip resonators and exploits the properties of a planar electromagnetic bandgap (EBG) structure patterned unto the ground plane of the printed circuit board material to provide a very wide stopband of up to 5 times the fundamental frequency. The...
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