Microwave oven with circular polarization
US4580023A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Mar 6, 1985 |
| Grant date | Apr 1, 1986 |
| Priority date | — |
| Expiry date | Mar 6, 2005 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH05B6/72
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A circularly polarized microwave oven. Microwave energy is coupled from a waveguide above the ceiling to the cavity by a rotatable vertical probe. A strip transmission line closely spaced to the ceiling to limit radiation therefrom conducts the microwave current from the probe to a helical strip antenna radially offset from the axis of the probe. The helical strip antenna has a cylindrical segment which has a downward slope from its feed end to gradually increase the spacing between the cylindrical segment and the ceiling which functions as a ground plane. The increase in radiative efficiency around the cylindrical segment caused by increasing the spacing to the ceiling offsets the magnitude of the current traveling wave diminishing as a result of radiation losses. Accordingly, the magnitude of the X and Y electric vectors are substantially equal over a relatively wide angle thus defining circular polarization. Connected to the opposite end of the cylindrical segment is a flat or horizontal segment of the helical antenna. Rotation of the probe about its axis moves the helical antenna in a horizontal circular path thus further enhancing the heating uniformity.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.