Effect of a finite ground plane thickness on the radiation pattern of an aperture antenna
06 Jun 1988-pp 34-37
TL;DR: In this paper, the effect of the ground plane thickness on the radiation pattern for aperture antennas with the slots assumed as sources of cylindrical or spherical waves is examined using the geometrical theory of diffraction (GTD).
Abstract: A convenient procedure to obtain the radiation pattern of slot antennas consists of assuming that the conducting ground plane containing the slot is infinitely long. While this may be adequate for obtaining the radiation pattern in the half space of the aperture, for obtaining the complete radiation pattern of the antenna the proper dimensions of the ground plane have to be considered. The effect of the ground plane thickness on the radiation pattern for aperture antennas with the slots assumed as sources of cylindrical or spherical waves is examined using the geometrical theory of diffraction (GTD). The diffraction from the upper and lower edges of the ground plane was calculated considering the multiple diffractions between the edges. Numerical results are presented and discussed. >
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TL;DR: In this article, a new technique for designing dual-band reconfigurable slot antennas is introduced based on loading a slot antenna with a lumped capacitor (or varactor) at a certain location along the slot.
Abstract: A new technique for designing dual-band reconfigurable slot antennas is introduced The technique is based on loading a slot antenna with a lumped capacitor (or varactor) at a certain location along the slot Given a fixed capacitor location along the slot, decreasing the capacitance results in increasing the first and second resonant frequencies of the slot antenna However, the changes in the resonant frequencies are significantly different for the first and second resonances and, hence, a dual-band antenna with considerable frequency ratio tuning range can be obtained Based on this technique, an electronically tunable dual-band antenna with a frequency ratio in the range of 12-165 is designed and fabricated using a single varactor with a capacitance range of 05-22 pF The antenna has similar radiation patterns with low cross-polarization levels at both bands and across the entire tunable frequency range
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Additional excerpts
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Dissertation•
01 Jan 2006
4 citations
Cites background from "Effect of a finite ground plane thi..."
...For a single band slot antenna, these effects have extensively been studied in the literature [76, 94, 95, 96, 97, 98, 99]....
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...plane size on the radiation patterns of a slot antenna are examined in [94, 95]....
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References
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TL;DR: The mathematical justification of the theory on the basis of electromagnetic theory is described, and the applicability of this theory, or a modification of it, to other branches of physics is explained.
Abstract: The geometrical theory of diffraction is an extension of geometrical optics which accounts for diffraction. It introduces diffracted rays in addition to the usual rays of geometrical optics. These rays are produced by incident rays which hit edges, corners, or vertices of boundary surfaces, or which graze such surfaces. Various laws of diffraction, analogous to the laws of reflection and refraction, are employed to characterize the diffracted rays. A modified form of Fermat’s principle, equivalent to these laws, can also be used. Diffracted wave fronts are defined, which can be found by a Huygens wavelet construction. There is an associated phase or eikonal function which satisfies the eikonal equation. In addition complex or imaginary rays are introduced. A field is associated with each ray and the total field at a point is the sum of the fields on all rays through the point. The phase of the field on a ray is proportional to the optical length of the ray from some reference point. The amplitude varies in accordance with the principle of conservation of energy in a narrow tube of rays. The initial value of the field on a diffracted ray is determined from the incident field with the aid of an appropriate diffraction coefficient. These diffraction coefficients are determined from certain canonical problems. They all vanish as the wavelength tends to zero. The theory is applied to diffraction by an aperture in a thin screen diffraction by a disk, etc., to illustrate it. Agreement is shown between the predictions of the theory and various other theoretical analyses of some of these problems. Experimental confirmation of the theory is also presented. The mathematical justification of the theory on the basis of electromagnetic theory is described. Finally, the applicability of this theory, or a modification of it, to other branches of physics is explained.
3,032 citations