Skin efekt u nehomogenim materijalima

master's thesis

• Title (english): Skin effect of inhomogeneous materials
• Author: Eduard Luka Mudri
• Mentor: Mario Basletić (mentor)
• Committee member: Mario Basletić (predsjednik povjerenstva)
• Committee member: Mihael Srđan Grbić (član povjerenstva)
• Committee member: Katarina Jeličić (član povjerenstva)
• Committee member: Ivan Kupčić (član povjerenstva)
• Committee member: Emil Tafra (član povjerenstva)
• Granter: University of Zagreb; Faculty of Science; (Department of Physics); Zagreb
• Defense date and country: 2021-06-01, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Physics

Abstract

Kako u fizici tako i u elektronici često moramo raditi s izmjeničnim strujama vrlo visokih frekvencija, u području mikrovalova i više. Kako impedancija vodiča i sklopovlja raste s frekvencijom tako često imamo nezanemarive omske gubitke koji se žele ukloniti. U linearnim vodičima vrijedi mikroskopski Ohmov zakon, to jest da je struja proporcionalna električnom polju. Sama električna i magnetska polja u vodiču se računaju pomoću Maxwellovih jednadžbi te su ona oscilatorne prirode. Zbog oscilatorne prirode polja struja može lokalno teći i u suprotnom smjeru od ukupne, te je to zaslužno za povećanje efektivnog električnog otpora. Za potrebe ovog rada zanima nas možemo li bušenjem materijala te stavljanjem slitine lošije vodljivosti u predjelima gdje lokalno struja teče u suprotnom smjeru smanjiti efektivan električni otpor. U radu dokazujemo relaciju koja nam kaže da to nije moguće, to jest da je otpor tog nehomogenog materijala uvijek veći ili jednak homogenom. U nastavku su dani primjeri za homogeni i nehomogeni slučaj u jednoj i dvije dimenzije.

Abstract (english)

In both physics and electronics we often have to work with alternating currents of very high frequencies, in the microwave range and more. As the impedance of conductors and circuits increases with frequency so often we have negligible ohmic losses that we want to remove. In linear conductors, the microscopic Ohm's law applies, that is, the current is proportional to the electric field. The electric and magnetic fields in the conductor are calculated using Maxwell's equations and are of an oscillatory nature. Due to the oscillatory nature of the field, the current can flow locally in the opposite direction from the total current and this is responsible for increasing of the effective electrical resistance. For the purposes of this paper, we are interested in whether we can reduce the effective electrical resistance by drilling the material and placing an alloy of poorer conductivity in areas where the current flows locally in the opposite direction. In this paper, we prove a relation that tells us that this is not possible, that is, that the resistance of this inhomogeneous material is always greater than or equal to homogeneous. The following are examples for homogeneous and inhomogeneous cases in one and two dimensions.

• Keywords: mikroskopski Ohmov zakon; Maxwellove jednadžbe; modificirane Besselove funkcije; skin efekt; dubina prodiranja; električno polje; gustoća struje; električni otpor
• Keywords (english): microscopic Ohm's law; Maxwell's equations; modified Bessel functions; skin effect; skin depth; electric field; current density; electrical resistance
• Language: croatian
• URN:NBN: urn:nbn:hr:217:007793
• Study programme: Title: Physics and Computer Science; specializations in: Education; Course: Education; Study programme type: university; Study level: integrated undergraduate and graduate; Academic / professional title: magistar/magistra edukacije fizike i informatike (magistar/magistra edukacije fizike i informatike)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2021-06-17 11:53:35