Question: In which area did this French engineer and physicist, whose name became synonymous to one of a series of concentric prolate ellipsoidal regions of space between and around a transmitting antenna and a receiving antenna system, contribute significantly?

full_context: Document 1: Augustin-Jean Fresnel: Augustin-Jean Fresnel ( ; ] ; 10 May 1788 – 14 July 1827) was a French engineer and physicist who contributed significantly to the establishment of the theory of wave optics. Fresnel studied the behaviour of light both theoretically and experimentally.
Document 2: Ibn Sahl: Ibn Sahl (Persian: ابن سهل‎ ‎ ) (Abu Saʿd al-ʿAlaʾ ibn Sahl ) (Arabic: أبو سعد العلاء ابن سهل‎ ‎ ) (c. 940–1000) was a Persian Muslim mathematician, physicist and optics engineer of the Islamic Golden Age associated with the Abbasid court of Baghdad. Ibn Sahl's 984 treatise "On Burning Mirrors and Lenses" sets out his understanding of how curved mirrors and lenses bend and focus light. Ibn Sahl is credited with first discovering the law of refraction, usually called Snell's law. He used the law of refraction to derive lens shapes that focus light with no geometric aberrations, known as anaclastic lenses.
Document 3: Foucault (crater): Foucault is a small lunar impact crater that lies along the southern edge of Mare Frigoris, to the southeast of the crater Harpalus. In the rugged terrain to the south of Foucault is Sharp. The outer perimeter of Foucault forms a somewhat irregular circle, with slight outward bulges to the south and northeast. The inner wall of the rim is not notably terraced, and slopes down directly to the uneven floor. It is named after physicist Léon Foucault, most famous for the Foucault pendulum.
Document 4: Two-ray ground-reflection model: The Two-Rays Ground Reflected Model is a radio propagation model which predicts the path losses between a transmitting antenna and a receiving antenna. Generally, the two antenna each have different height. The received signal having two components, the LOS (line of sight) component and the multipath component formed predominately by a single ground reflected wave.
Document 5: Benoît Paul Émile Clapeyron: Benoît Paul Émile Clapeyron (] ; 26 February 1799 – 28 January 1864) was a French engineer and physicist, one of the founders of thermodynamics.
Document 6: Henri Bénard: Henri Claude Bénard, (25 October 1874 – 29 March 1939), French physicist, best known for his research on convection in liquids that now carries his name, Bénard convection. In addition, the historical surveys of both Tokaty and von Kármán both acknowledge that Bénard studied the vortex shedding phenomenon later named the von Karman vortex street, prior to von Karman's own contributions. Bénard specialized in experimental fluid dynamics, and the use of optical methods to study it. He was a faculty member at the universities at Lyon, Bordeaux, and finally the Sorbonne in Paris.
Document 7: Christian Doppler: Christian Andreas Doppler ( ; ] ; 29 November 1803 – 17 March 1853) was an Austrian mathematician and physicist. He is celebrated for his principle — known as the Doppler effect — that the observed frequency of a wave depends on the relative speed of the source and the observer. He used this concept to explain the color of binary stars.
Document 8: Fresnel diffraction: In optics, the Fresnel diffraction equation for near-field diffraction is an approximation of Kirchhoff–Fresnel diffraction that can be applied to the propagation of waves in the near field. It is used to calculate the diffraction pattern created by waves passing through an aperture or around an object, when viewed from relatively close to the object. In contrast the diffraction pattern in the far field region is given by the Fraunhofer diffraction equation.
Document 9: Fresnel zone: A Fresnel zone ( ), named for physicist Augustin-Jean Fresnel, is one of a series of concentric prolate ellipsoidal regions of space between and around a transmitting antenna and a receiving antenna system. The concept is used to understand and compute the strength of waves (such as sound or radio waves) propagating between a transmitter and a receiver.
Document 10: Free-space path loss: In telecommunication,free-space path loss (FSPL) is the attenuation of radio energy between the feedpoints of two antennas that results from the combination of the receiving antenna's capture area plus the obstacle free, line-of-sight path through free space (usually air). The "Standard Definitions of Terms for Antennas", IEEE Std 145-1993, defines "free-space loss" as "The loss between two isotropic radiators in free space, expressed as a power ratio." Despite this name and definition, the FSPL includes a receiving antenna aperture component in the total attenuation. It does not include any loss associated with hardware imperfections, or the effects of any antenna gains. A discussion of these losses may be found in the article on link budget. The FSPL is rarely used standalone, but rather as a part of the Friis transmission formula, which includes the gain of antennas.
Document 11: Fraunhofer diffraction: In optics, the Fraunhofer diffraction equation is used to model the diffraction of waves when the diffraction pattern is viewed at a long distance from the diffracting object, and also when it is viewed at the focal plane of an imaging lens. In contrast, the diffraction pattern created near the object, in the near field region, is given by the Fresnel diffraction equation.
Document 12: Christiaan Huygens: Christiaan Huygens, FRS ( or ; ] ) (Latin: "Hugenius" ) (14 April 1629 – 8 July 1695) was a prominent Dutch mathematician and scientist. He is known particularly as an astronomer, physicist, probabilist and horologist.
Document 13: Gustave Eiffel: Alexandre Gustave Eiffel (born Bönickhausen; ; ] ; 25 December 1832 – 27 December 1923) was a French civil engineer and architect. A graduate of École Centrale Paris, he made his name with various bridges for the French railway network, most famously the Garabit viaduct. He is best known for the world-famous Eiffel Tower, built for the 1889 Universal Exposition in Paris, and his contribution to building the Statue of Liberty in New York. After his retirement from engineering, Eiffel focused on research into meteorology and aerodynamics, making significant contributions in both fields.
Document 14: Léon Foucault: Jean Bernard Léon Foucault (] ; 18 September 1819 – 11 February 1868) was a French physicist best known for his demonstration of the Foucault pendulum, a device demonstrating the effect of the Earth's rotation. He also made an early measurement of the speed of light, discovered eddy currents, and is credited with naming the gyroscope.
Document 15: Franz–Keldysh effect: The Franz–Keldysh effect is a change in optical absorption by a semiconductor when an electric field is applied. The effect is named after the German physicist Walter Franz and Russian physicist Leonid Keldysh (nephew of Mstislav Keldysh).
ground_truth: theory of wave optics