Considerations for resonant slot arrays for microwave food drying and heating

Antennas for microwave heating radiate high levels of power relative to communications and most radar applications. The problem of voltage breakdown becomes a dominant factor in the antenna design. The breakdown problem is compounded when the heating is in a partial vacuum, which can be worse than the full vacuum situation of space-borne antennas. Resonant slot array antennas are ideal for microwave heating because of their variable aperture design and high efficiency except for the slot voltage breakdown problem. This paper presents new design results for antenna array design for microwave heating, based on maximum electric-field considerations. As an example design, a seven-slot waveguide array with a slot width of λ
₀
/4 is found to be suitable for 1 kilowatt (a typical magnetron), based on a criteria of keeping the electric field below 3% of free-space breakdown.