The phase center of horn antennas
IBM1
TL;DR: In this paper, the phase center for an arbitrary plane is calculated from the E- and H -plane phase centers, and the dependence of the phase centers on horn dimensions is shown. But this is based on a vector approach, by deriving the phase centre from the expressions for the far field.
Abstract: The calculation of phase centers for rectangular and diagonal horns is presented. The calculation is based on a vector approach, by deriving the phase center from the expressions for the far field. Different expressions are derived for the phase center of the E and H planes. The phase center for an arbitrary plane is calculated from the E- and H -plane phase centers. Graphs are presented showing the dependence of the phase centers on horn dimensions.
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TL;DR: In this paper, the far-field radiation pattern of a 4*4 diagonal horn array, measured at 100 GHz, was calculated by aperture integration, and the results indicated that the fraction of the power radiated into the fundamental Gaussian mode is about 84%.
Abstract: The far-field radiation pattern of a diagonal horn has been calculated by aperture integration. The radiation patterns for a 4*4 diagonal horn array, measured at 100 GHz, agree very well with theoretical predictions. The aperture electric field was also expanded into Gauss-Hermite modes. The results indicate that the fraction of the power radiated into the fundamental Gaussian mode is about 84%. About 10% of the power is radiated in the cross-polarized component. >
123 citations
TL;DR: In this paper, the radiation characteristics of diagonal horns are investigated by means of Gaussian-Hermite modes, and it is shown that, for reasonably long horns, the beamwidths in the principal and 45 degrees planes are equal to within 10%, and all sidelobes are below -15 dB.
Abstract: The radiation characteristics of diagonal horns are investigated by means of Gaussian-Hermite modes. It is shown that, for reasonably long horns, the beamwidths in the principal and 45 degrees planes are equal to within 10%, and all sidelobes are below -15 dB. It is also demonstrated that the phase center of a diffraction-limited horn is close to the aperture, whereas the phase center of a constant-beamwidth horn is behind the throat. The maximum coupling to the lowest order copolar Gaussian mode is 84%, and the total amount of power coupled into the cross-polarized lobes is 9.5%. More significantly, the aperture efficiency of a Cassegrain antenna fed by a diagonal horn has a maximum value of 81%, which compares with 87% for a corrugated horn. The maximum efficiency is achieved when the aperture of a diffraction-limited horn is placed at a confocal tertiary focus, although a secondary focus gives an aperture efficiency that is only 10% lower, suggesting that diagonal horns are suitable for focal-plane arrays. >
49 citations
TL;DR: In this article, the effects of antenna phase-center displacement on distance determination in time-correlation radio positioning systems are discussed, and a simple method to determine the distance error versus observation angle, derived from the antenna phase center displacement, is presented.
Abstract: This paper presents a tutorial discussion of the effects of antenna phase-center displacement on distance determination in time-correlation radio positioning systems. A technique to determine the antenna phase-center displacement as a function of observation angle is reviewed. A simple method to determine the distance error versus observation angle, derived from the antenna phase-center displacement, is then presented. Numerical distance-error predictions, determined directly from antenna phase-center displacement, are presented for a Yagi and a log-periodic antenna used in a commercial UHF radio distance-measurement system. Finally, the measured distance error versus observation angle for these antennas as determined in several field trials is presented, validating the numerical predictions.
44 citations
TL;DR: The proposed antenna model avoids the need for phase-center determination for proximal soil characterization and shows that the antenna transfer function model is valid only when the antenna is not too close to the reflector, namely, the threshold above which it holds corresponds to the antenna size.
Abstract: The antenna of a zero-offset off-ground ground-penetrating radar can be accurately modeled using a linear system of frequency-dependent complex scalar transfer functions under the assumption that the electric field measured by the antenna locally tends to a plane wave. First, we analyze to which extent this hypothesis holds as a function of the antenna height above a multilayered medium. Second, we compare different methods to estimate the antenna phase center, namely, 1) extrapolation of peak-to-peak reflection values in the time domain and 2) frequency-domain full-waveform inversion assuming both frequency-independent and -dependent phase centers. For that purpose, we performed radar measurements at different heights above a perfect electrical conductor. Two different horn antennas operating, respectively, in the frequency ranges 0.2-2.0 and 0.8-2.6 GHz were used and compared. In the limits of the antenna geometry, we observed that antenna modeling results were not significantly affected by the position of the phase center. This implies that the transfer function model inherently accounts for the phase-center positions. The results also showed that the antenna transfer function model is valid only when the antenna is not too close to the reflector, namely, the threshold above which it holds corresponds to the antenna size. The effect of the frequency dependence of the phase-center position was further tested for a two-layered sandy soil subject to different water contents. The results showed that the proposed antenna model avoids the need for phase-center determination for proximal soil characterization.
42 citations
Cites background from "The phase center of horn antennas"
...K. Z. Jadoon and H. Vereecken are with the Institute of Bio- and Geosciences, Agrosphere (IBG-3), Forschungszentrum Jülich GmbH, 52425 Jülich, Germany (e-mail: k.z.jadoon@fz-juelich.de; h.vereecken@fz-juelich.de)....
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TL;DR: In this article, the design of a multimode feed horn for use in a monopulse feed system is summarized and the amplitude and phase patterns are computed in consideration of achieving the desired aperture distributions for the sum and difference beams.
Abstract: The design of a multimode feed horn for use in a monopulse feed system is summarized. Both amplitude and phase patterns have been obtained and compared with measurements. The far-field amplitude and phase patterns are computed in consideration of achieving the desired aperture distributions for the sum and difference beams. The phase center of the horn is discussed in relation to the multimode excitation and frequency dispersion. It is shown that the phase center location moves as the mode content changes, and proper adjustment of the mode content will result in design optimization. Some tradeoff curves are also presented for design optimization. >
37 citations
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TL;DR: In this article, a method of locating the phase center of any radiating system from the expression of its radiating field is formulated and applied to electromagnetic horns of different dimensions and flare angles.
Abstract: A method of locating the phase center of any radiating system from the expression of its radiating field is formulated. This method is then applied to electromagnetic horns of different dimensions and flare angles. It is believed that the results and discussions presented in this paper will be useful in the design and positioning of the feeding horn such that the paraboloidal reflector will produce a desirable radiation pattern.
49 citations
TL;DR: The previous formula of Nagelberg for determining the location of the phase center of the aperture antennas was examined by calculating the phase patterns of a radiation field as mentioned in this paper, and it was shown that the phase centre should not be located at the aperture, but at the point determined by the expression derived here.
Abstract: The previous formula of Nagelberg for determining the location of the phase center of aperture antennas is examined by calculating the phase patterns of a radiation field. The results show that the phase center should not be located at the aperture, but at the point determined by the expression derived here.
13 citations