KR20130078298A - Rotman lens with asymmetrical sturcture and beam forming antenna by using thereof - Google Patents

Abstract

PURPOSE: A Rotman lens having an asymmetric structure and a switched beam antenna using the same are provided to implement a system including an antenna, a beam forming lens, and a circuit, thereby offering a compact package in a planar form which facilitates the installation of millimeter wave band signal radar. CONSTITUTION: A Rotman lens (100) includes a first conductive layer (110) which includes a first internal reflection prevention unit for reducing the reflection inside the conductive layer; a first dielectric layer (120) which is positioned on one side of the first conductive layer; a second internal reflection prevention unit which corresponds to the first internal reflection prevention unit and is to reduce the reflection inside; and a second conductive layer (130) which is positioned on one side of the first dielectric layer and has an asymmetric structure to the first conductive layer.

Description

RATMAN LENS WITH ASYMMETRICAL STURCTURE AND BEAM FORMING ANTENNA BY USING THEREOF

The present invention relates to a Lotman lens and a beam shaping antenna using the same, and more particularly, to provide a Lotman lens having an asymmetrically designed structure and a beam shaping antenna using the same.

The ultra-high frequency lens implements the principle of the optical lens in the ultra-high frequency band, and in 1963, a method of implementing a parallel plate waveguide by Rotman and Turner was introduced. Here, as the optical lens has a sufficient thickness compared to the wavelength of the light wave, the ultra-high frequency lens is also required to have a sufficient size corresponding to several times the wavelength of the electromagnetic wave.

Therefore, in order to solve the shortcomings of the method of implementing the ultra-high frequency lens using the parallel plate waveguide, the research on the method of implementing the ultra-high frequency lens using the microstrip substrate which can realize the small size and light weight through the shortening of the wavelength by the relative dielectric constant Actively progressed.

The trifocal lens, also known as the Rotman lens, was initially designed with a thin plate structure, but recently, due to its compactness and ease of manufacture, a dielectric between the ground conductor and the microstrip-shaped conductor pattern It is implemented in the form of arranging. As a patent for a phased array antenna using such a microstrip ultra-high frequency lens, there is a US Patent No. 5099253. This patent discloses an antenna system consisting of an antenna having a plurality of elements and a microwave lens, wherein the microwave lens is composed of a parallel plate area, beam ports and array ports, and a plurality of elements on one wall of the parallel plate. Beam ports are arranged, and a plurality of array ports are arranged on the wall opposite the wall.

As shown in FIG. 1, a conventional microstrip-type ultrahigh-frequency lens has a parallel plate region 11 and a first parallel plate region having a shape according to Rotman's formula or Shelton's symmetric formula. Ground conductors are provided with a conductor pattern having a plurality of beam ports 12 in the form of microstrips arranged along the wall (focal arc of the lens) and a plurality of array ports 13 in the form of microstrips arranged along the second wall of the lens. It is formed by placing on a plate and inserting a dielectric between them.

Ultra-high frequency lenses, such as the conventional microstrip Rotman lens shown in FIG. 1 were mainly developed for military use, and since the wavelength is applied in the ultra-high frequency region of centimeters, the Teflon substrate having a relative dielectric constant of 3 or less is mainly used. Developed. In addition, it has been used for the purpose of steering the radiation by dividing the wide steering range at a constant angle (the beam range is not dense because the wide range is divided by a certain number of beams).

In addition, the beam shaping antenna of the ultra-high frequency band or millimeter wave band electrically controlling the direction of the antenna beam has many applications. Beam-forming antennas are widely applied to weapon systems such as radar and electronic warfare equipment, automobile collision avoidance devices, automatic landing devices, and communication repeaters.

Beamforming antennas using ultra-high frequency lenses such as the Rotman lens have the advantages of low cost, simple structure, high reliability, and small size. Lotman lenses can generate multiple beams, have low phase and amplitude errors, and operate over a wide frequency range.

When implementing a radar using a Lotman lens, one side (array port) should be connected to the antenna and the other side (beam port) should be connected to the circuit. Antennas, lenses, and circuits shall be separated by a ground plane, with the exception of the connections (eg slots).

To date, all Rottman's lenses pattern one metal surface of the substrate and the other metal surface is used as the ground plane. Therefore, the lens-shaped pattern surface of the board | substrate patterned both the array port and the beam port on the same surface. In this case, either the array port or the beam port must pass through one layer in the middle. Currently, the connection between adjacent layers of a multilayer circuit board uses a slot or via structure, which requires low insertion loss. However, in the case of passing through more than one layer in the middle, there was a problem in that the loss of input was very large.

One embodiment of the present invention for solving the above technical problem is a first conductor layer including a first internal anti-reflection to reduce the reflection inside the conductor layer; A first dielectric layer positioned on one surface of the first conductor layer; And a second internal antireflection portion corresponding to the first internal antireflection portion and reducing internal reflection, and located on one surface of the first dielectric layer and having an asymmetrical structure with the first conductor layer. It may be characterized by providing a lotman lens characterized in that it comprises a conductor layer.

The first conductor layer may further include a beam pattern surface having beam ports arranged in a first predetermined number and a first ground surface having a second predetermined number of slots, and the second conductor layer A second ground plane having a first predetermined number of slots and an array port surface on which a second predetermined number of array ports are arranged may be further provided.

In addition, the beam pattern surface and the first ground plane forms a symmetrical structure around the first internal reflection prevention portion, and the second ground plane is formed on the beam pattern surface side, and is located at a position of the distal end of the beam port. Slots may be provided at corresponding positions, and the arrangement port surface may be characterized in that the distal end portion of the arrangement port is positioned to correspond to the position of the second predetermined number of slots.

Preferably, the first internal anti-reflection portion is an internal anti-reflection portion formed by positioning the area ratio of the first ground plane and the second ground plane to be 3: 2.

Preferably, the first internal antireflection portion and the second internal antireflection portion are dummy ports.

One embodiment of the present invention for solving the above technical problem is a beam shaping antenna in which a third conductor layer, a second dielectric, a Lotman lens, a third dielectric and a fourth conductor layer are sequentially stacked, and the Lotman lens A first conductor layer comprising a first internal antireflective portion for reducing reflection within the conductor layer; A first dielectric layer positioned on one surface of the first conductor layer; And a second internal antireflection portion corresponding to the first internal antireflection portion and reducing internal reflection, and located on one surface of the first dielectric layer and having an asymmetrical structure with the first conductor layer. It may be characterized by providing a beam shaping antenna, characterized in that the lotman lens characterized in that it comprises a conductor layer.

The first conductor layer may further include a beam pattern surface having a first predetermined number of beam ports and a first ground surface having a second predetermined number of slots, and the second conductive layer having a first predetermined number. And an array port surface on which a second ground plane having a slot and a second predetermined number of array ports are arranged.

In addition, the beam pattern surface and the first ground plane forms a symmetrical structure around the first internal reflection prevention portion, and the second ground plane is formed on the beam pattern surface side, and is located at a position of the distal end of the beam port. Slots may be provided at corresponding positions, and the arrangement port surface may be characterized in that the distal end portion of the arrangement port is positioned to correspond to the position of the second predetermined number of slots.

In addition, the third conductor layer has a second predetermined number of antennas arranged, and a second predetermined number of antenna delay lines connected to the arranged antennas, and the first ground plane is located at an end portion of the antenna delay line. The slot may be provided at a position corresponding to the antenna delay line, and the array port surface may be connected via a slot of the first ground plane.

The fourth conductor layer has a predetermined circuit and a first predetermined number of circuit delay lines connected to the circuit, and the second ground plane has a slot corresponding to a position of the end portion of the circuit delay line. The circuit delay line and the beam pattern surface may be connected via a slot of the second ground surface.

Preferably, the first internal reflection prevention portion may be an internal reflection prevention portion formed by positioning the area ratio of the first ground plane and the second ground plane to be 3: 2.

Preferably, the first internal reflection prevention portion and the second internal reflection prevention portion may be dummy ports.

The present invention provides an antenna, a beam forming lens, and a Lotman lens for implementing a system consisting entirely of a circuit, and a beam shaping antenna using the same, thereby providing a flat and compact packaging that is easy to mount a millimeter wave radar. have.

1 is a reference diagram for describing a microstrip lotman lens as a conventional technology.
2 is a reference diagram for explaining a lens formula for a Lotman lens.
3 illustrates a Lotman lens having an asymmetric structure according to an embodiment of the present invention.
4 is a reference diagram for describing a first conductor layer and a second conductor layer of a Lotman lens having an asymmetric structure according to an embodiment of the present invention.
5 illustrates a beam shaping antenna using a Lotman lens having an asymmetric structure according to an embodiment of the present invention.
FIG. 6 is a reference diagram illustrating a first conductor layer, a second conductor layer, a third conductor layer, and a fourth conductor layer of a Lotman lens having an asymmetric structure according to an embodiment of the present invention.

Hereinafter, some embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail.

The following embodiments are a combination of elements and features of the present invention in a predetermined form. Each component or feature may be considered to be optional unless otherwise stated. Each component or feature may be implemented in a form that is not combined with other components or features. In addition, some of the elements and / or features may be combined to form an embodiment of the present invention. The order of the operations described in the embodiments of the present invention may be changed. Some configurations or features of certain embodiments may be included in other embodiments, or may be replaced with corresponding configurations or features of other embodiments.

Embodiments of the invention may be implemented through various means. For example, embodiments of the present invention may be implemented by hardware, firmware, software, or a combination thereof.

For a hardware implementation, the method according to embodiments of the present invention may be implemented in one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs) , Field programmable gate arrays (FPGAs), processors, controllers, microcontrollers, microprocessors, and the like.

In the case of an implementation by firmware or software, the method according to embodiments of the present invention may be implemented in the form of a module, a procedure or a function for performing the functions or operations described above. The software code can be stored in a memory unit and driven by the processor. The memory unit may be located inside or outside the processor, and may exchange data with the processor by various well-known means.

Specific terms used in the following description are provided to help the understanding of the present invention, and the use of the specific terms may be modified in other forms without departing from the technical spirit of the present invention.

A lotman lens will be described with reference to FIG. 2. Lotman lenses can be easily designed using lens formulas. 2 is a view showing design parameters for the design of a typical Lotman lens. Referring to FIG. 2, as a design parameter, a focal arc, an array curve, an array antenna plane, a delay line, a focal length F, and a focus curve Radius (R), beam angel (α), scan angle (φ), position of array antenna (N), length of nth delay line (delay length) (Wn), coordinate of array curve (P (X, Y)), the dielectric constant εr of the substrate, and the effective dielectric constant εeff of the substrate.

In general, N, W, X, Y, and G values can be normalized to a focal length F as shown in the following equation for ease of calculation in designing a Lotman lens.

[Equation 1]

n = N / F, w = W / F, x = X / F, y = Y / F, g = G / F

a0 = sin (α), b0 = sin (φ), b1 = cos (φ), and the dielectric constant (εr) and effective dielectric constant (εeff) of the substrate, beam angle (α), scan angle (φ), After setting the g value, the w value according to the n value is calculated using the following equation.

Next, using the calculated w value, the dielectric constant of the substrate (εr) and the effective dielectric constant (εeff), the scan angles (b0, b1), and the g value, the coordinates x and y of the array curve are obtained using the following equation. Calculate

On the other hand, since the focus curve is an arc, it is possible to calculate the center point (-g + r) and the radius (r) value.

A lotman lens according to an embodiment of the present invention will be described with reference to FIG. 3. In the Lotman lens 100 according to the exemplary embodiment, the first conductor layer 110, the first dielectric 120, and the second conductor layer 130 are stacked in this order.

The first conductor layer includes a beam pattern surface 111 having a beam port arranged thereon, a first ground plane 113, and an internal reflection prevention part 117, and the second conductor layer has an array port surface ( 131, a second ground plane 133, and an internal reflection prevention part 137 are provided.

In the present invention, the Lotman lens 100 is, for example, the first conductor layer 110 by etching and removing unnecessary copper foil from a copper foil laminated film bonded to copper foil having a predetermined thickness based on an insulator such as a polyimide film or the like. Array port surface 131, second ground surface 133 of the beam pattern surface 111, the first ground surface 113, the first internal anti-reflective portion 117, and the second conductor layer 130. The second internal reflection prevention part 137 may be formed.

The beam pattern surface of the first conductor layer and the first ground plane are symmetrically formed, and the array port surface and the second ground plane of the second conductor layer are symmetrically formed, and thus the microstrip input structure is also symmetrically designed. Therefore, both the beam port of the beam pattern surface and the array port of the array port surface can enter and exit without passing through the intermediate layer.

The internal anti-reflection portion is for reducing internal reflection of the conductor layer. According to an embodiment of the present invention, the first internal anti-reflection portion may reduce internal reflection of the first conductor layer and reduce internal reflection of the second conductor layer. It has a second internal antireflection to reduce it. The first internal reflection prevention portion and the second internal reflection prevention portion may be formed in the same shape to correspond to each other.

At this time, the area of the ground plane is roughly half, but the circuit generally requires very little ground plane, and the antenna can also be applied to a small antenna that requires a relatively small ground plane, which is preferable for a three-layer structure for system implementation.

Preferably, since the second ground plane for the beam pattern plane connected to the circuit requires a relatively smaller ground plane than the first ground plane for the array pattern plane connected to the antenna, the second ground plane may be adjusted at a preset ratio. That is, by adjusting the area ratio of the first ground plane and the second ground plane differently, it is possible to improve the performance of the lotman lens. Preferably, the area ratio of the second ground plane is set within a range of 50 to 75% of the first ground plane to reduce the internal reflection of the conductor layer while maintaining the performance of the beam pattern plane and the antenna pattern plane.

The internal anti-reflection portion may be implemented by designing a dummy port or an absorbing side wall, and by appropriately reducing internal reflection according to the design of the present invention, a three-layer layer (antenna, lens) (Lot, circuit) can implement a lens beamforming antenna.

The present invention is a complete system because it is possible to use a microstrip-slot-microstrip transition that is easy to manufacture by designing the array port side and the beam port side of the lens asymmetrically so that the ground plane can be placed on the upper and lower layers of the lens. Three layers (antenna, lens, and circuit) necessary for this structure can be realized with minimum transition loss.

A lotman lens having an asymmetric structure according to an embodiment of the present invention will be described in more detail with reference to FIG. 4.

In the beam pattern surface 111 of the first conductor layer 110, beam ports are arranged in a first predetermined number. The first predetermined number is preferably set to a number that can minimize the loss when the circuit is connected to the circuit.

The first ground plane 113 of the first conductor layer 110 has a slot 31. The first ground plane has a second predetermined number of slots 115. The first ground plane may use a metal plate or an aluminum plate, for example. The first ground plane may be implemented to half the area of the first conductor layer, but preferably implemented to occupy two-thirds of the area of the first conductor layer to prevent loss of performance input of the array port connected to the antenna. It is appropriate for that.

The second predetermined number means a number capable of obtaining radio waves of a desired frequency band by the user.

The beam pattern surface 111 and the first ground surface 113 form a symmetrical structure around the first internal antireflection portion. That is, the first internal reflection prevention portion is preferably formed at a position to reduce internal reflection that may be generated due to the symmetrical structure of the beam pattern surface 111 and the first ground surface 113.

For example, a dielectric material having ε _r = 3 and a thickness of 0.508 mm may be used as the first dielectric 120.

The second conductor layer has a second ground plane 133 having a first predetermined number of slots and an array port surface 131 having a second predetermined number of array ports arranged.

The distal end of the array port is positioned so that the array port surface 131 corresponds to the position of the second predetermined number of slots 115. An array port is arranged at a position for passing the second predetermined number of slots 115 so that the lot can be connected to the lens body and the antenna.

The second ground plane 133 is formed on the side of the first beam pattern surface 111 of the first conductor layer, and includes a slot at a position corresponding to the position of the distal end portion of the beam port. Preferably, since the second ground plane for the beam pattern plane connected to the circuit requires a relatively smaller ground plane than the first ground plane for the array pattern plane connected to the antenna, the second ground plane may be adjusted at a preset ratio. That is, by adjusting the area ratio of the first ground plane and the second ground plane differently, it is possible to improve the performance of the lotman lens. Preferably, the area ratio of the second ground plane is set within a range of 50 to 75% of the first ground plane to reduce the internal reflection of the conductor layer while maintaining the performance of the beam pattern plane and the antenna pattern plane.

A beamforming antenna using a Lotman lens having an asymmetric structure according to an embodiment of the present invention will be described with reference to FIG. 5. A beamforming antenna according to an embodiment of the present invention is a beam shaping antenna in which a third conductor layer, a second dielectric, a Lotman lens, a third dielectric, and a fourth conductor layer are sequentially stacked, and the Lotman lens is a first conductor. It is a Lotman lens in which a layer, a first dielectric, and a second conductor layer are sequentially stacked. The same contents as those described above for the Lotman lens are replaced with the above contents.

For example, a dielectric material having ε _r = 3 and a thickness of 0.508 mm may be used as the first dielectric material 220, the second dielectric material 250, and the third dielectric material 260.

The third conductor layer has a second predetermined number of antennas arranged, and a second predetermined number of antenna delay lines connected to the arranged antennas.

The first ground plane has a slot corresponding to the position of the second predetermined number of antenna delay line end portions, and the antenna delay line and the array port face are connected via the slot of the first ground plane.

The fourth conductor layer has a predetermined circuit and a first predetermined number of circuit delay lines connected to the circuit, and the second ground plane has a slot corresponding to the position of the end portion of the circuit delay line, and the circuit delay line. And the beam pattern surface are connected via a slot of the second ground surface.

As in the present invention, if the ground planes of the array port side and the beam port side of the Lotman lens are symmetrically, and the microstrip input structure is also symmetrically designed, both the array port and the beam port can enter and exit without the intermediate layer. . The anticipated internal reflection problem due to the symmetrical design is adequately reduced through the design of the dummy port or the absorbing side wall to form a lotman lens beam consisting of three layers (antennas, lenses, and circuits), which are the minimum layers required for the system. An antenna can be implemented.

So far I looked at the center of the preferred embodiment for the present invention. It will be understood by those skilled in the art that the present invention may be embodied in various other forms without departing from the spirit or essential characteristics thereof. Therefore, the disclosed embodiments should be considered in descriptive sense only and not for purposes of limitation. The scope of the present invention is shown not in the above description but in the claims, and all differences within the scope should be construed as being included in the present invention.

Claims (12)

A first conductor layer comprising a first internal anti-reflective portion for reducing reflection within the conductor layer;
A first dielectric layer positioned on one surface of the first conductor layer; And
A second conductor corresponding to the first internal anti-reflection portion and including a second internal anti-reflection portion for reducing internal reflection and positioned on one surface of the first dielectric layer and having an asymmetrical structure with the first conductor layer A lotman lens comprising a layer. The method according to claim 1,
The first conductor layer further includes a beam pattern surface on which beam ports are arranged in a first predetermined number and a first ground surface having a second predetermined number of slots,
And the second conductor layer further comprises a second ground plane having a first predetermined number of slots and an array port surface on which a second predetermined number of array ports are arranged.
The method of claim 2,
The beam pattern surface and the first ground plane form a symmetrical structure around the first internal antireflection portion,
The second ground plane is formed on the beam pattern surface side and has a slot corresponding to the position of the distal end of the beam port.
And the distal end portion of the array port is positioned so that the array port surface corresponds to the position of the second predetermined number of slots.
The method of claim 3, wherein the first internal reflection prevention portion
And an internal antireflection part configured to adjust an area ratio between the first ground plane and the second ground plane at a preset ratio.
The lotman lens of claim 4, wherein the first internal reflection prevention portion and the second internal reflection prevention portion are dummy ports.
A beam shaping antenna in which a third conductor layer, a second dielectric, a Lotman lens, a third dielectric, and a fourth conductor layer are sequentially stacked,
The lotman lens
A first conductor layer comprising a first internal anti-reflective portion for reducing reflection within the conductor layer;
A first dielectric layer positioned on one surface of the first conductor layer; And
A second conductor corresponding to the first internal anti-reflection portion and including a second internal anti-reflection portion for reducing internal reflection and positioned on one surface of the first dielectric layer and having an asymmetrical structure with the first conductor layer A beam shaping antenna, characterized in that it is a lotman lens comprising a layer.
The method of claim 6,
The first conductor layer further includes a beam pattern surface on which beam ports are arranged in a first predetermined number and a first ground surface having a second predetermined number of slots,
And the second conductor layer further comprises a second ground plane having a first predetermined number of slots and an array port surface on which a second predetermined number of array ports are arranged.
The method of claim 7, wherein
The beam pattern surface and the first ground plane form a symmetrical structure around the first internal antireflection portion,
The second ground plane is formed on the beam pattern surface side and has a slot corresponding to the position of the distal end of the beam port.
And the distal end portion of the array port is positioned so that the array port surface corresponds to the position of the second predetermined number of slots.
The method of claim 8,
The third conductor layer has a second predetermined number of antennas arranged, and a second predetermined number of antenna delay lines connected to the arranged antennas,
The first ground plane has a slot corresponding to the position of the end portion of the antenna delay line,
And the antenna delay line and the array port surface are connected via slots of the first ground plane.
The method of claim 8,
The fourth conductor layer has a predetermined circuit and a first predetermined number of circuit delay lines connected to the circuit,
The second ground plane has a slot corresponding to a position of the end portion of the circuit delay line,
And the circuit delay line and the beam pattern surface are connected via a slot of the second ground surface.
The method of claim 8, wherein the first internal reflection prevention portion
And an internal antireflection part configured to adjust an area ratio of the first ground plane and the second ground plane to a preset ratio.
12. The beam shaping antenna of claim 11, wherein the first internal antireflection portion and the second internal antireflection portion are dummy ports.

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