Introduction IntroductionFor many years designers of microwave systems have been interested in efficient power radiation from waveguide structures. Waveguide-fed slot antenna arrays have been used as a resonant and traveling-wave antennas in many ground-based and airborne radar systems. In these arrays, a desired radiation pattern can be created by adjustment of the position of the slots in the waveguide wall.
Recently, the designers of microwave ovens has become interested in slotted waveguides as a new feeding systems alternative to traditional open-end waveguides. However, the efforts to create efficient construction haven't always been fully successful. This can be attributed to the lack of theoretical and systematic studies of behavior of the slotted waveguides in this specific capacity.
It appears that, at the present time, the best way to give the designers an advice regarding the most efficient constructions of the slotted waveguides as excitation systems of microwave ovens would be to apply an appropriate electromagnetic simulator for comprehensive analysis of the waveguide connected with the oven (loaded with a lossy material) via the series of radiating slots.
To this end, we use the universal 3D conformal FDTD simulator QuickWave-3D. In this project, we focus on major characteristics of a slot structure operating as an oven feed as well as criteria of its practical design. These issues have not received appropriate consideration yet and thus seem to be of crucial practical value.
GoalsThe coupling C (defined as a percentage of the source energy absorbed by the load) is an important parameter which can be interpreted as a numerical characteristic of the system efficiency. Since in our case C can be estimated from the reflection coefficient |S11|, the main goal of the ongoing simulations is to figure out how to make |S11| as small as possible in some range around the operating frequency. To facilitate the study of this complex multi-parametric problem, we first address the influence of a few geometrical parameters whose impact on the reflection coefficient is supposed to be most significant.
Some Technical DetailsThe object of ongoing consideration:
Operating frequency: 2.45 GHz
Waveguide: WR430 (86 x 43 mm)
Cavity (Daewoo 800 W oven): a x b x c = 320 x 330 x 214 mm
