Çizgisel Kaynak ile Odak Dışı Beslenen Bir Parabolik Reflektörden Kırınan Alanlar

Öz

Bir çizgisel kaynağın bir silindirik parabolik mükemmel elektriksel iletken (MEİ) reflektör antenden kaynaklanan kırınan alanları Geliştirilmiş Fiziksel Optik’in (Modified Theory of Physical Optics; MTPO) saçınım integrali kullanılarak incelenmiştir. Reflektör, çizgisel kaynak tarafından odak-dışı olarak beslenmiştir. Köşe kırınım alanları, Köşe Noktası Metodu (Edge Point Method) kullanılarak asimptotik olarak hesaplanmıştır. Üniform kırınan alanları elde etmede kullanılan hesaplamada Signum (İşaret) ve Fresnel fonksiyonları yardımıyla üniform olmayan durum ortadan kaldırılmıştır. Toplam saçılan, kırınan ve yansıyan alanlar sayısal olarak, parabol genişliği, çizgisel kaynağın konum açısı gibi problemin bazı parametreleri için çizdirilmiştir.

Anahtar Kelimeler

• Çizgisek Kaynak
• Parabolik Anten
• Odak-dışı besleme
• Kırınım

Diffracted Fields by a Parabolic Reflector Offset-Fed by a Line Source

Öz

Fields of a line source diffracted by a cylindrical parabolic Perfectly Electric Conducting (PEC) reflector are investigated by employing the scattering integral of the Modified Theory of Physical Optics (MTPO). The reflector that is symmetrically located with respect to x-axis is offset-fed by a line source. The line source is lying parallel to the z-axis and off the focus of the reflector. Diffracted fields are evaluated asymptotically by means of the Edge Point Method. An approximate way of expressing uniform diffracted fields is used by utilizing the Signum and Fresnel functions together to overcome the non-uniform situations. Total scattered, diffracted, and reflected fields are plotted numerically for some parameters such as parabola width and location angle of the line source in the problem.

Anahtar Kelimeler

• Line Source
• ParabolicAntenna
• Offset feed
• Diffraction

Kaynakça

1. Ingerson, P. G., Wong, W. C. (1974). Focal region characteristics of offset fed reflectors. Antennas and Propagation Society International Symposium 12, 121-123.
2. Sharma, S. B., Pujara, D., Chakrabarty, S. B., et. al. (2009). Cross-polarization cancellation in an offset parabolic reflector antenna using a corrugated matched feed. IEEE Antennas and Wireless Propagation Letters, 8, 861-864.
3. Adatia, N. A., Rudge, A. W. (1975). Beam squint in circularly polarised offset-reflector antennas. Electronics Letters, 11, 513-515.
4. Rudge, A. W., Adatia, N. A. ( 1975). New class of primary-feed antennas for use with offset parabolic-reflector antennas. Electronics Letters, 11, 597-599.
5. Watson, K., Rudge, A. W., Adatia, N. A. (1978). Dual-polarized mode generator for cross-polar compensation in parabolic reflector antennas. 8th European Microwave Conference, Paris, France,183–187.
6. Strutzman, W., Terada, M. (1993). Design of offset-parabolic-reflector antennas for low cross-pol. and low sidelobes. IEEE Antennas Propagation Magazine, 35, 46-49.
7. Rudge, A.W. (1973). Improving the cross-polar performance of an offset parabolic reflector antenna using a rectangular matched feed. Electronic Letters, 9, 611-613.
8. Watson, W. H.(1964). Offset-reflector antennas with offset feeds. IEEE Transactions on Antennas and Propagation, 12, 561-569.

9. Hasselman, F. J. V., Felsen, L. B. (1982). Asymptotic analysis of parabolic reflector antennas. IEEE Transactions on Antennas and Propagation, 30, 677-685.
10. Suedan, G. A., Jull, E. V. (1991). Beam diffraction by planar and parabolic reflectors. IEEE Transactions on Antennas and Propagation, 39, 521-527.
11. Zamboni-Rached, M., De Assis, M. C., Ambrosio, L. A. (2015). Diffraction-resistant scalar beams generated by a parabolic reflector and a source of spherical waves. Applied Optics, 54, 5949-5955.
12. Kennaugh, E., Ott, R. (1964). Fields in the focal region of a parabolic receiving antenna. IEEE Transactions on Antennas and Propagation, 12 (3), 376-377.
13. Rudge, A. W. (1969). Focal-plane field distribution of parabolic reflectors. Electronics Letters, 5, 510-512.
14. James, G.L., Poulton, G.T. (1973). Modified diffraction coefficients for focusing reflectors. Electronics Letters, 9, 537-538.
15. Knop, C. M., Ostertag, E. L. (1977, July). A note on the asymptotic physical optic solution to the scattered fields from a paraboloidal reflector. IEEE Transactions on Antennas and Propagation, 531-534.
16. Suedan, G. A., Jull, E. V. (1989). Beam diffraction by parabolic reflector. Digest on Antennas and Propagation Society International Symposium, 1, 274-277.
17. Umul, Y. Z. (2008). Scattering of a line source by a cylindrical parabolic impedance surface. Journal of Optical Society of America, 25, 1652-1659.
18. Umul, Y. Z. (2004). Modified theory of physical optics. Optics Express, 12, 4959-4972.
19. Kara, M. (2016). Scattering of a plane wave by a cylindrical parabolic perfectly electric conducting reflector. Optik, 127, 4531–4535.
20. Sarnık, M., Yalçın, U. (2017). Uniform scattered fields from a perfectly conducting parabolic reflector with modified theory of physical optics. Optik, 135, 320-326.
21. Yalçın, U. (2007). Scattering from a cylindrical reflector: modified theory of physical optics solution. Journal of Optical Society of America, 24, 502-506.