A waveguide window contains a central transverse pane of a material with high dielectric constant such as alumina ceramic. The central pane is an integral number of half-wavelengths thick. On each side of the central pane and immediately adjacent it is a side pane of material with relatively low dielectric constant such as fused quartz. The side panes are odd numbers of quarter-wavelengths thick. The dielectric constants of the side panes are preferably the square root of the dielectric constant of the central pane. The improved wave impedance matching provides a low wave reflection over a wide frequency band.

Sealed wave guide window

Triple-pane waveguide window

A high-power microwave window structure is disclosed. The window structure includes a hollow waveguide having a dielectric wave permeable gastight partition sealed thereacross to form the window assembly. The window structure is capable of being impedance matched to the waveguide structure to provide a relatively wide passband. In certain windows the passband can be as wide as the recommended bandwidth for the waveguide itself. Such window structures are plagued by ''''trapped'''' and ''''ghost'''' resonant modes which are excited into resonance by slight asymmetries in the window structure. At their resonant frequencies, these modes couple energy from the main propogating mode to produce an impedance mismatch and at high-power levels, overheating and failure of the window structure. Thus, operation at high-power levels is typically restricted to frequency ranges between a pair of such resonant modes. The frequency separation between the resonant modes is increased to provide broader band operation by selectively tuning the resonant frequencies of these modes by selectively varying the electrical path length through the window structure for one or more of these modes. For example, the window is made thicker near the periphery where one of the resonant modes has its most intense electric fields and made thinner near the center where another of the modes has its intense electric fields to tune one of the modes higher in frequency, while the other mode is being tuned lower in frequency. The mean thickness of the window is maintained approximately constant such as not to change appreciably the passband for the main propagating mode. Alternatively, the dielectric constant for various portions of the window can be changed for changing the electrical path length through the window as aforedescribed.

Microwave window having dielectric variations for tuning of resonances

Waveguide window structure having three resonant sections giving broadband transmission with means to fluid cool center section

Controlling ghost-mode resonant frequencies in sealed waveguide windows

Electromagnetic wave permeable window

This invention relates to transmission systems of the wave guide type, and particularly to wave guides for conveying plane polarized waves and wave guide phase changers for shifting the phase of plane polarized waves. As disclosed in Patent 2,409,183, granted on October 15, 1946, to A. C....

Sealed wave guide window

Citations

Triple-pane waveguide window

Microwave window having dielectric variations for tuning of resonances

Waveguide window structure having three resonant sections giving broadband transmission with means to fluid cool center section

Controlling ghost-mode resonant frequencies in sealed waveguide windows

Electromagnetic wave permeable window

References

Microwave transmission system

Wave guide impedance transformer

Wave energy polarization converter

Wave-guide window

Wave guide seal and filter structure

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