Clear etalon windows for domestic microwave ovens: Analysis and measurement

R. L. Boxman, E. Yaari, V. Dikhtyar, E. Gidalevich, V. Zhitomirsky

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

Abstract

Conventional microwave oven windows block microwave leakage with a metal grid, however the visibility is poor. Here we present a new window design concept with enhanced visibility using thin transparent conductive films forming a microwave etalon, comprised of two transparent conductive thin films, separated by a distance L of a lossless medium. The ideal case of normally incident plane waves was analyzed. It was found that there were transmission minima when L was equal to an odd multiple of λ/4, where λ is the microwave wavelength in the inter-film medium. Reflection was significant when R<<η, where R is the surface resistivity of the film and η is the wave impedance of the medium. Etalon characteristics were numerically simulated and experimentally measured for a domestic oven retrofitted with an etalon window assembled from commercially available glass coated with R=7 Ω/□ films. Microwave transmission is higher than in the plane wave case, because of the higher transmission of TM modes at oblique incidence. Microwave transmission was minimized for 0.24<L/λ<0.35, with average leakage of 0.10-0.14 mW/cm2 with a water load of 300 ml, compared to 0.20 mW/cm2 through the original grid. The simulated and measured leakage vs L curves had the same shape, but the measured leakage was an order of magnitude higher than the simulated. Good agreement was obtained when R=12 Ω/□ films were assumed, suggesting that the film resistivity was higher at 2.45 GHz than at d.c. The etalon window fabricated from inexpensive, commercially available coated glass provided a clear view of the oven contents, met radiation leakage standards, and had lower radiation leakage than the conventional metal grid window.

Original languageEnglish
Title of host publicationMicrowave and RF Power Applications
Subtitle of host publicationProceeding of the 13th International Conference on Microwave and Radio Frequency Heating, AMPERE 2011
PublisherEditions Cepadues
Pages286-289
Number of pages4
ISBN (Print)9782854289787
StatePublished - 2011
Event13th International Conference on Microwave and Radio Frequency Heating, AMPERE 2011 - Toulouse, France
Duration: 5 Sep 20118 Sep 2011

Publication series

NameMicrowave and RF Power Applications: Proceeding of the 13th International Conference on Microwave and Radio Frequency Heating, AMPERE 2011

Conference

Conference13th International Conference on Microwave and Radio Frequency Heating, AMPERE 2011
Country/TerritoryFrance
CityToulouse
Period5/09/118/09/11

Keywords

  • Etalon
  • Food visibility
  • Interference filter
  • Microwave oven window

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