Equivalence of physical optics and aperture field integration method in the full pattern analysis

Oodo, I.; Ando, Makoto

doi:10.1109/aps.1994.407809

Cited by 5 publications

(3 citation statements)

References 4 publications

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“…Based on facts derived from the equivalence theorem, the authors have confirmed that AFIM provides a field which matches PO in all of the observation regions if the equivalent currents in Eq. (8) are used for the integration surface [14]:…”

Section: Equivalent Currents Integral Representation and Asymptoticmentioning

confidence: 99%

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Elimination of fictitious penetrating rays from PO and hybridization with AFIM

Shijo

Ando

2004

Elect. Eng. Jpn.

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SUMMARYPhysical optics (PO) is an approximation method for high-frequency scattering and diffraction problems. But PO fields are inaccurate in the shadow region where the source is screened by the scatter. Two key factors of the error for PO are (i) edge diffraction coefficients and (ii) existence of fictitious penetrating rays. The correction with respect to the former has been extensively investigated by many authors using various ray techniques such as GTD, UTD, and UAT. On the other hand, the latter was identified recently by the authors. This paper proposes novel PObased calculation procedures termed PO-AF and PTD-AF, where PO and Aperture Field Integration Method (AFIM) are merged with the help of special elementary diffraction coefficients. These can uniformly cover the whole angular region and only the error factor (ii) is removed in PO-AF while both (i) and (ii) are removed in PTD-AF. The theoretical backgrounds of PO currents are discussed in terms of field equivalence theorem and visualization of EM waves. Next, new methods are proposed and their validity is numerically demonstrated for 2D scattering problems of a strip, a corner reflector, and a cylinder of circular arc.

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Section: Equivalent Currents Integral Representation and Asymptoticmentioning

confidence: 99%

“…First, based on the equivalence theorem for the PO current (2n × H i ), the component radiating into the shadow region of the scatterer (n × H [3,12,13] used when approximating, for instance, radiation toward the shadow and the main beam regions in a reflector antenna [14]. AFIM + is also known as the Kirchhoff approximation.…”

Section: Introductionmentioning

confidence: 99%

Elimination of fictitious penetrating rays from PO and hybridization with AFIM

Shijo

Ando

2004

Elect. Eng. Jpn.

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“…Extract t h e mechanism of P O errors AFIM+ and AFIM-currents form respectively the shadow by canceling the dircct incident waves and the reHection from the scatterer [2]. AFIM+ currents do not radiate the scattering fields from the inncr edges in terms of field equivalence theorem.…”

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confidence: 99%

Novel interpretation of physical optics errors, fictitious penetrating rays and corrections by hybrid use of PO and AFIM

Shijo

Ando

Proceedings of the 16th International Symposium on Power Semiconductor Devices &Amp; IC's

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Novel interpretation of the physical optics (PO) is discussed and two mechanisms are identified as the error factors, that is, (1) errors in diffraction coefficients and (2) fictitious penetrating raysll]. Based upon these observations, new methods named PO-AF and PTD-AF are proposed which eliminate the fictitious penetrating rays from PO and PTD, respectively.The accuracy is confirmed numerically for corner reflectors and circular arc reflectors. 2PO approximation is generally inaccurate in the shadow region, in which the direct incident waves from the source are screened by the scatterer. In correction of PO errors, most of works were directed to factor (l), which cause the perturbation in the edges; PTD was improved about factor (1) by GTD diffraction coefficients. The effect of t,b: fictitious peiictrating rays (2), which is named to be based upon intensive interpretation of the rays cmanating from invisible edges, has liardly at all been discussed and evaluated in detail. The purpose of this study is to extract the niechanisni of the generation of the fictitious penetrating rays and to correct PO by removing them Firstly, PO currents are decomposed into two currents, whicli are the scts of equivalent currents in the aperture field integration method (AFIM) for reflection and shadow waves (Table 1).Extract t h e mechanism of P O errors AFIM+ and AFIM-currents form respectively the shadow by canceling the dircct incident waves and the reHection from the scatterer[2]. AFIM+ currents do not radiate the scattering fields from the inncr edges in terms of field equivalence theorem. AFIM-currents. on the other hand, causes the radiation from the invisible edges, that is the fictitious penetrating rays, as if they are generated by images corresponding to the reflections.

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