Parabolic antenna with an integrated sub reflector
A sensor for a fill level measuring device for determining the fill level in a container by determining the delay time of high-frequency signals, comprising a main reflector having an edge region and an inner region, a sub reflector, which is connected to the edge region of the main reflector via a radome, an inner space, which is encompassed by the radome and the main reflector, and a hollow waveguide which is connected to the main reflector and has a front end, which is oriented toward the sub reflector for coupling electromagnetic waves in and/or out, wherein the radome and the sub reflector are embodied as integral or unitary in formation.
1. A sensor, for a fill level measuring device for determining the fill level in a container by determining the delay time of high-frequency signals, comprising:
a main reflector having an edge region and an inner region;
a sub reflector, operatively connected to the edge region of the main reflector via a radome;
an inner space encompassed by the radome and the main reflector; and
a hollow waveguide which is operatively positioned and connected to the main reflector and has a front end, said front end being oriented toward the sub reflector for coupling electromagnetic waves thereto;
the radome and the sub reflector are embodied being integral with each other; and
the front end of the hollow waveguide is embodied in the shape of a horn, and preferably is filled with a second solid dielectric material.
2. The sensor, according to claim 1 , wherein:
the sub reflector and the radome are made of a first dielectric material; and
said dielectric material that makes up the sub reflector has a metal coating on a side that faces the inner space.
3. The sensor, according to claim 1 , wherein:
the inner space is sealed, pressure-tight and vacuum-tight, from an outer space that surrounds the sensor.
4. The sensor, according to claim 1 , wherein:
the edge region of the main reflector is embodied as a collar which encompasses the inner region; and
said collar is a tubular collar that encompasses the inner region and projects in the direction of radiation.
5. The sensor, according to claim 1 , wherein:
the edge region of the main reflector has a sealing surface and is in an operatively leak-proof connection between the radome and the main reflector.
6. The sensor, according to claim 5 , further comprising:
at least one O-ring between the edge region of the main reflector and the radome; and
said O-ring operatively positioned for sealing the inner space in relation to the outer space that surrounds the sensor.
7. The sensor, according to claim 1 , wherein:
the main reflector is embodied as paraboloid, and is either made of a metal or has a metal coating on an inner region side that faces the inner space.
8. The sensor, according to claim 1 , wherein:
the sub reflector is elliptical or hyperbolic in shape.
9. The sensor, according to claim 1 , wherein:
the sensor is embodied as a Gregory antenna or a Cassegrain antenna.
10. The sensor, according to claim 1 , wherein:
the radome is made of a plastic, preferably one of PP and PTFE.
11. The sensor, according to claim 1 , wherein:
the radome is made of one of a glass fiber reinforced plastic and a high-performance plastic; and said high-performing plastic being one of PEEK and PEI.
12. The sensor, according to claim 1 , wherein:
the radome is embodied as convex or conical.
13. The sensor, according to claim 1 , wherein:
the thickness of the radome is such that it corresponds to a whole-number multiple of one-half the dielectric wavelength of a coupled-in electromagnetic wave, wherein the wavelength preferably corresponds to a wavelength of the W-band, particularly preferably a wavelength of between 77 GHz and 81 GHz.
14. A method, for measuring a fill level in a container, comprising the steps of:
providing a sensor operative for determining the fill level in the container by determining a delay time of high-frequency signals and for radiating and receiving electromagnetic radiation;
said sensor further comprising
a main reflector having an edge region and an inner region;
a sub reflector, operatively connected to the edge region of the main reflector via a radome;
an inner space encompassed by the radome and the main reflector; and
a hollow waveguide which is operatively positioned and connected to the main reflector and has a front end, said front end being oriented toward the sub reflector for coupling electromagnetic waves thereto;
the radome and the sub reflector are embodied being integral with each other; and
the front end of the hollow waveguide is embodied in the shape of a horn, and preferably is filled with a second solid dielectric material.