Patent Description:
The following description relates to a level measurement technology, and more particularly, to a radio detection and ranging (RADAR) level gauging apparatus.

In a level measurement technology using a radio detecting and ranging (RADAR) signal, a RADAR level gauging apparatus, which is installed above a tank for storing liquid and the like, emits a RADAR signal in a direction perpendicular to a level interface in the tank and receives the RADAR signal reflected from the level interface, thereby measuring a level.

Since an emission time, a reception time, and a speed of the RADAR signal are values to be measured, a distance from an emission position of the RADAR signal to the level interface can be measured, and thus a level can be determined.

<CIT>) proposes a RADAR level gauge in which a transceiver network, a processing network, and signal and power interfaces are enclosed in a housing, and a transceiver circuit is electrically connected to a signal propagation device extending into the tank.

In order to reduce interference with other devices using the same frequency, a radar level gauging apparatus should reduce a side lobe as much as possible at a signal emission angle of ±<NUM>° or more. In the conventional radar level gauging apparatus, a method of reducing a side lobe includes a method of increasing a length of a horn, a method of using a corrugated horn, and a method of using a dielectric loaded horn.

The method of increasing a length of a horn has a disadvantage of increasing a size of the radar level gauging apparatus. The method of using a corrugated horn should corrugate a side surface of a corrugated horn and thus has a disadvantage in that machining precision should be increased in the case of a high frequency which requires a reduced depth and width of a corrugated portion due to a short wavelength.

Meanwhile, the method of using a dielectric loaded horn has a disadvantage in that a shape of a dielectric should be precisely made as a frequency is increased and, since a length of the dielectric through which radio waves pass is long, loss of the dielectric is great.

The following description relates to a radio detection and ranging (RADAR) level gauging apparatus which allows a side lobe, which is a factor that degrades level measurement precision and interferes with other devices, to be reduced and of which a size is allowed to be miniaturized.

In one general aspect, a RADAR level gauging apparatus includes an antenna configured to emit a RADAR signal to a level interface and receive the RADAR signal reflected from the level interface, and a controller configured to perform transmission control for the RADAR signal emitted by the antenna, reception control for the RADAR signal received by the antenna, and level measurement control using the received RADAR signal, wherein the antenna includes a lens through which the RADAR signal is transmitted or received in a direction perpendicular to the level interface, and an absorber configured to reduce a side lobe of the RADAR signal transmitted or received through the lens.

According to the general aspect of the present invention, the lens is a Luneburg lens of which a total length is minimizable because a distance between a focal point and a lens is short and through which the RADAR signal, which is transmitted and received in a wide direction, is focusable in the direction perpendicular to the level interface.

According to an additional aspect of the present invention, in order to satisfy Federal Communications Commission (FCC) regulations, the antenna may be implemented to emit a RADAR signal having a beam width of <NUM> dB at an emission angle of less than <NUM>°.

According to an additional aspect of the present invention, in order to satisfy the FCC regulations, the antenna may be implemented to emit a RADAR signal having a side lobe level of less than -<NUM> dB at an emission angle of ±<NUM>° or more.

According to an additional aspect of the present invention, the antenna may further include a cylinder antenna of which an inside is protected by being wrapped around an outside thereof and which simultaneously serve as a waveguide and serve to reduce a side lobe which is an interference component with other devices.

According to the general aspect of the present invention, the antenna further includes a waveguide configured to guide the RADAR signal between the controller and the Luneburg lens, at least two lateral fixing rods configured to laterally fix the Luneburg lens, and an upper support configured to support the Luneburg lens in a direction from top to bottom, wherein the upper support comprises a first upper support configured to support the Luneburg lens in an apex portion above the Luneburg lens, and a second upper support installed between the at least two lateral fixing rods and the first upper support and configured to partially support an upper spherical surface of the Luneburg lens.

According to an additional aspect of the present invention, the controller may include a RADAR signal generator configured to generate the RADAR signal for measuring a level; a trigger signal generator configured to generate a periodic trigger signal for whether to transmit or receive the RADAR signal; a RADAR signal transmission/reception processor configured to process and transmit, in response to the trigger signal generated by the trigger signal generator, the RADAR signal generated by the RADAR signal generator to periodically emit the RADAR signal to the level interface through the antenna or configured to receive and process the RADAR signal reflected from the level interface and periodically received through the antenna; and a level measurement part configured to periodically measure the level using the RADAR signal which is periodically received and processed by the RADAR signal transmission/reception processor and reflected from the level interface.

The following description is provided to assist the reader in gaining a comprehensive understanding of the methods, apparatuses, and/or systems described herein. Accordingly, various changes, modifications, and equivalents of the methods, apparatuses, and/or systems described herein will be suggested to those of ordinary skill in the art.

Also, descriptions of well-known functions and constructions may be omitted for increased clarity and conciseness.

When a component is referred to as being "connected" or "coupled" to another component, it may be directly connected or coupled to another component, but it should be understood that still another component may be present between the component and another component.

In contrast, when a component is referred to as being "directly connected" or "directly coupled" to another component, it should be understood that still another component may not be present between the component and another component.

<FIG> is a block diagram illustrating a configuration of one embodiment of a radio detection and ranging (RADAR) level gauging apparatus according to the present invention. As shown in <FIG>, a RADAR level gauging apparatus <NUM> according to the present embodiment includes an antenna <NUM> and a controller <NUM>.

The antenna <NUM> emits a RADAR signal to a level interface and receives the RADAR signal reflected from the level interface. For example, in order to satisfy Federal Communications Commission (FCC) regulations, the antenna <NUM> may be implemented to emit a RADAR signal having a beam width of <NUM> dB at an emission angle of less than <NUM>°.

Alternatively, in order to satisfy the FCC regulations, the antenna <NUM> may be implemented to emit a RADAR signal having a side lobe level of less than -<NUM> dB at an emission angle of ±<NUM>° or more.

<FIG> is a perspective projection illustrating a configuration of one embodiment of an antenna of the RADAR level gauging apparatus according to the present invention, and <FIG> is a cross-sectional view illustrating the configuration of one embodiment of the antenna of the RADAR level gauging apparatus according to the present invention.

As shown in <FIG> and <FIG>, in order to improve a level measurement performance by reducing a side lobe which is a noise component, the antenna <NUM> includes a lens <NUM> and an absorber <NUM>.

A RADAR signal is transmitted and received in a direction perpendicular to the level interface through the lens <NUM>. According to the invention, the lens <NUM> is a Luneburg lens of which a total length may be minimized because a distance between a focal point and a lens is short and through which RADAR signals, which are transmitted and received in a wide direction, may be focused in a direction perpendicular to a level interface.

When the Luneburg lens is used as the lens <NUM>, a propagation path of the RADAR signal may be reduced and the RADAR signal may be concentrated in the direction perpendicular to the level interface so that a size of the RADAR level gauging apparatus may be miniaturized and a level measurement performance may be improved.

The absorber <NUM> reduces a side lobe of the RADAR signal transmitted and received through the lens <NUM>. In this case, the absorber <NUM> may be disposed on a front surface of the lens <NUM> in the direction perpendicular to the level interface.

For example, the absorber <NUM> may be made of an electromagnetic wave absorbing dielectric material containing a carbon-based or nitrile-based material and may remove a current flowing along a surface of the absorber <NUM> to be implemented to reduce a side lobe which is an interference component with other devices.

A current flows only along a surface of a dielectric and does not flow in the dielectric which acts as a non-conductor. Thus, the absorber <NUM> is made of the electromagnetic wave absorbing dielectric material to reduce a current flowing along the surface of the absorber <NUM> so that the side lobe, which is an interference component with other devices, may be reduced.

Due to the absorber <NUM>, a RADAR signal having a beam width of <NUM> dB at an emission angle of less than <NUM>° and a side lobe level of less than -<NUM> dB at an emission angle of ±<NUM>° or more may be emitted so that the FCC regulations may be satisfied.

<FIG> is a diagram illustrating a main lobe and a side lobe according to an emission angle of a RADAR signal emitted by the RADAR level gauging apparatus according to the present invention. Referring to <FIG>, it can be seen that a RADAR signal including a main lobe having a beam width of <NUM> dB at an emission angle of less than <NUM>° and a side lobe having a beam width of less than -<NUM> dB at an emission angle of ±<NUM>° or more is emitted.

The controller <NUM> performs control, which includes transmission control for RADAR signals emitted by the antenna <NUM>, reception control for the RADAR signals received by the antenna <NUM>, and level measurement control using the received RADAR signals, on an overall operation of the RADAR level gauging apparatus.

For example, the controller <NUM> may include a RADAR signal generator <NUM>, a trigger signal generator <NUM>, a RADAR signal transmission/reception processor <NUM>, and a level measurement part <NUM>, which may be modularized on a printed circuit board (PCB) mounted in a PCB mounting groove formed in an apex portion of the antenna <NUM>.

The RADAR signal generator <NUM> generates a RADAR signal for level measurement. For example, the RADAR signal generator <NUM> may be implemented to generate a pulse signal having a frequency ranging from <NUM> to <NUM> or a frequency modulated continuous wave (FMCW) signal, but the present invention is not limited thereto.

The trigger signal generator <NUM> generates a periodic trigger signal for whether to transmit or receive a RADAR signal. The trigger signal generated by the trigger signal generator <NUM> is periodically transmitted to the RADAR signal transmission/reception processor <NUM>.

In response to the trigger signal generated by the trigger signal generator <NUM>, the RADAR signal transmission/reception processor <NUM> processes and transmits the RADAR signal generated by the RADAR signal generator <NUM> to periodically emit the RADAR signal to the level interface through the antenna <NUM> or receives and processes the RADAR signal reflected from the level interface and periodically received through the antenna <NUM>.

The level measurement part <NUM> periodically measures a level using the RADAR signal which is periodically received and processed by the RADAR signal transmission/reception processor <NUM> and is reflected from the level interface. An algorithm for measuring a level using the RADAR signal reflected from the level interface is an algorithm which is already known prior to the present application, and thus a detailed description thereof will be omitted herein.

Since an emission time, a reception time, and a speed of the RADAR signal are values to be measured, a distance from an emission position of the RADAR signal to the level interface may be measured through the level measurement part <NUM>, and thus the level may be measured.

Since the present invention is implemented as described above, it is possible to reduce a side lobe which is a factor that degrades level measurement precision and interferes with other devices. The level measurement precision may be improved and the RADAR level gauging apparatus may be miniaturized so that convenience of a user may be improved.

Meanwhile, according to an additional aspect of the present invention, the antenna <NUM> may further include a cylinder antenna <NUM>. The inside of the cylinder antenna <NUM> is protected by being wrapped around the outside thereof, and the cylinder antenna <NUM> simultaneously serves as a waveguide and serves to reduce a side lobe which is an interference component with other devices.

Due to the cylinder antenna <NUM>, a side lobe is partially suppressed at an emission angle of ±<NUM>° or more. For example, the cylinder antenna <NUM> may be made of a metal material such as aluminum (Al) or a stainless steel (SUS), and a cover 113a is coupled to an end portion of the cylinder antenna <NUM>.

Since the cylinder antenna <NUM> is implemented with a length sufficient for covering and protecting the lens <NUM> and the absorber <NUM> in the antenna <NUM>, a propagation path of the RADAR signal is relatively reduced when compared to the conventional radar level gauging apparatuses using a corrugated horn so that the radar level gauging apparatus may be miniaturized.

According to the present invention, the antenna <NUM> further includes a waveguide <NUM>, at least two lateral fixing rods <NUM>, and an upper support <NUM>.

The waveguide <NUM> guides the RADAR signal between the controller <NUM> and the Luneburg lens. The RADAR signal transmitted and received between the Luneburg lens and the RADAR signal transmission/reception processor <NUM> of the controller <NUM> is guided through the waveguide <NUM>.

The at least two lateral fixing rods <NUM> laterally fix the Luneburg lens. For example, four lateral fixing rods <NUM> may be provided in front-rear and lateral directions to be implemented to firmly fix the Luneburg lens laterally, but the present invention is not limited thereto.

The upper support <NUM> supports the Luneburg lens in a direction from top to bottom. According to the invention, the upper support <NUM> has a structure including a first upper support 116a configured to support the Luneburg lens in an apex portion above the Luneburg lens, and a second upper support 116b installed between at least two lateral fixing rods <NUM> and the first upper support 116a and configured to partially support an upper spherical surface of the Luneburg lens.

In addition, when the radar level gauging apparatus is assembled upside down, the upper support <NUM> supports the Luneburg lens in a direction from bottom to top to serve to facilitate assembly of the lateral fixing rod <NUM>.

With such implementation, in a state in which the Luneburg lens is fixed without movement due to the at least two lateral fixing rods <NUM> and upper support <NUM>, the RADAR signal is guided between the Luneburg lens and the RADAR signal transmission/reception processor <NUM> of the controller <NUM> through the waveguide <NUM> so that it is possible to prevent degradation of a level measurement performance due to movement of the Luneburg lens.

Alternatively, according to an additional aspect of the present invention, the RADAR signal generator <NUM> may be implemented to generate a pulse signal having a frequency ranging from <NUM> to <NUM> or a FMCW signal.

In this case, in order to satisfy the FCC regulations, the antenna <NUM> may be implemented to emit a RADAR signal having a beam width of <NUM> dB at an emission angle of less than <NUM>°.

Alternatively, in order to satisfy the FCC regulations, the antenna <NUM> may be implemented to emit a RADAR signal having a side lobe level of less than -22dB at an emission angle of ±<NUM>° or more.

As described above, it is possible to reduce a side lobe which is a factor that degrades level measurement precision and interferes with other devices so that the level measurement precision may be improved and the RADAR level gauging apparatus may be miniaturized, and thus convenience of a user may be improved.

In accordance with the present invention, there is an effect in that it is possible to reduce a side lobe, which is a factor that degrades level measurement precision and interferes with other devices so that the level measurement precision can be improved and the RADAR level gauging apparatus can be miniaturized, and thus convenience of a user can be improved.

Claim 1:
A radio detection and ranging, RADAR, level gauging apparatus (<NUM>) comprising:
an antenna (<NUM>) configured to emit a RADAR signal to a level interface and receive the RADAR signal reflected from the level interface; and
a controller (<NUM>) configured to perform transmission control for the RADAR signal emitted by the antenna (<NUM>), reception control for the RADAR signal received by the antenna (<NUM>), and level measurement control using the received RADAR signal,
wherein the antenna (<NUM>) includes:
a lens (<NUM>) through which the RADAR signal is transmitted and received in a direction perpendicular to the level interface,
wherein the lens (<NUM>) includes a Luneburg lens of which a total length is minimizable because a distance between a focal point and a lens is short and
through which the RADAR signal, which is transmitted and received in a wide direction, is focusable in the direction perpendicular to the level interface;
an absorber (<NUM>) configured to reduce a side lobe of the RADAR signal transmitted and received through the lens (<NUM>);
a waveguide (<NUM>) configured to guide the RADAR signal between the controller (<NUM>) and the Luneburg lens (<NUM>);
at least two lateral fixing rods (<NUM>) configured to laterally fix the Luneburg lens (<NUM>); and
an upper support (<NUM>) configured to support the Luneburg lens (<NUM>) in a direction from top to bottom, wherein
the upper support (<NUM>) comprises:
a first upper support (116a) configured to support the Luneburg lens (<NUM>) in an apex portion above the Luneburg lens (<NUM>); and
a second upper support (116b) installed between the at least two lateral fixing rods (<NUM>) and the first upper support (116a) and configured to partially support an upper spherical surface of the Luneburg lens (<NUM>).