Patent attributes
An antenna in a radar level gauge for determining the level of the surface of a medium stored in a tank. The antenna has a first and a second electrically conductive layer, and between the conductive layers a dielectric layer. The second of the conductive layers is provided with a number of holes in a predetermined pattern. Leading to the center of the dielectric layer is a transmission line. The microwaves from a radar unit in the radar level gauge are supplied to the dielectric layer in the antenna via the transmission line and transmitted out in a radial direction from a feed point in the dielectric layer that acts as a waveguide. Via said holes in the second conductive layer a microwave beam radiates out. Due to matching of the phase of the microwave and the placing of the individual holes in the pattern that the holes form, a predominant waveguide mode of the desired order is obtained.
