WO2017078187A1 - Array antenna - Google Patents

Abstract

The present invention provides an array antenna having the properties of high gain and a low side lobe level with respect to horizontal and vertical directions on the basis of Chebyshev array functions. The array antenna comprises: a plurality of radiation elements; at least one radiation unit comprising a feeder line for connecting the plurality of radiation elements; and a power distribution unit for distributing, at a first ratio, power supplied from a feeding unit to the at least one radiation unit.

Description

Array antenna

The present invention relates to an array antenna in which radiating elements are arranged in series.

Patch array antennas in the form of printed microstrips are commonly used in radar detectors for the 24 GHz Industrial, Scientific and Medical (ISM) band. In this case, for the special characteristics of the antenna, such as increasing the gain of the antenna or lowering the side lobe level (SLL), the Chebyshev, binomial, and taylor ( Complex structures such as taylor) need to be applied to the array antenna. In this case, a complex feeding circuit is required for feeding each radiating element. The design and performance optimization of array antennas with complex feed circuits takes a long time.

In order to solve the above problems due to the complexity of the design, the patch array antenna for the 24 GHz band is designed to uniformly input the magnitude and phase of the current into each patch. However, array antennas with a uniform magnitude and phase of the current input into the patch exhibit high sidelobe level characteristics, resulting in a very uneven detection area. In addition, when the detection area of the radar detector is very narrow, the side lobe level of the beam generated by the array antenna is high, so that it is difficult to generate a narrow and uniform beam only by the radar algorithm.

An array antenna having high gain and low side lobe level characteristics is provided.

According to one embodiment, a power distribution for distributing the power provided from the feeder at a first rate to the at least one radiating part comprising a plurality of radiating elements, a feed line connecting the plurality of radiating elements, and at least one radiating part. An array antenna is provided comprising a portion.

The first ratio in the array antenna may be determined based on an array function related to the side lobe level in the first direction that is perpendicular to the direction in which the plurality of radiating elements are arranged.

In the array antenna, the conductance of the first radiating element located in the center of the radiating part of the plurality of radiating elements may be greater than the conductance of at least one second radiating element located at the edge of the radiating part of the plurality of radiating elements.

The conductance of the plurality of radiating elements in the array antenna may be reduced at a second rate in a second direction from the first radiating element to the at least one second radiating element.

The second ratio in the array antenna may be a ratio determined based on an array function related to the side lobe levels in the second direction.

The array function in the array antenna may be a chebyshev array function.

The size of the plurality of radiating elements in the array antenna may be reduced at a second rate in a second direction from the first radiating element to the at least one second radiating element.

The second ratio in the array antenna may be a ratio of the feed factor determined based on the array factor function of the array antenna and the array function related to the side lobe level in the second direction.

The feeding coefficient in the array antenna may be a coefficient determined by comparing the coefficients of the array factor function and the array function.

The array antenna may further include a dielectric substrate on which at least one radiating part is printed in a patch form.

In the array antenna, the feed line may control the phase of the current input to the plurality of radiating elements.

In the array antenna, a feed line may connect a plurality of radiating elements in series.

In the array antenna, the power divider may match the impedance of the at least one radiator with respect to the feeder.

In the array antenna, the power divider may include at least one radiator, at least one first power divider providing power distributed at a first rate, and at least one first power divider to share the power provided from the feeder. It may include a second power distribution to provide in size.

The impedance of the first power divider in the array antenna may be determined according to the first ratio and a predetermined impedance constant.

According to an embodiment of the present disclosure, the beam is sharply formed through the high gain and the narrow 3dB radiation angle characteristic (HPBW _3dB = 4.0 °) to perform centralized monitoring on a specific sensing area. In addition, uniform sensing performance in the horizontal and vertical directions may be secured by implementing a sub-level (-20 dB) or less in the horizontal and vertical directions based on the Chebyshev arrangement function. By adjusting the phase of the current input to each radiating element from the array antenna 100 according to an embodiment, a beam having various inclinations may be formed in a forward direction, and the width of the beam may be adjusted by adjusting the number of radiating elements. Can be controlled. In addition, it is possible to facilitate feeding of each radiating element based on various functions, and there is an advantage in mass production because of the printed structure.

1A is a diagram illustrating a plan view of an array antenna according to an exemplary embodiment, and FIG. 1B is a diagram illustrating a perspective view.

2 is a diagram illustrating a radiator included in an array antenna according to an exemplary embodiment.

3 is a diagram illustrating a power distribution unit according to an exemplary embodiment.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

1A is a diagram illustrating a plan view of an array antenna according to an exemplary embodiment, and FIG. 1B is a diagram illustrating a perspective view.

1A and 1B, the array antenna 100 according to an embodiment includes a radiating unit 110, a power distribution unit 120, and a power feeding unit 130. The radiating unit 110, the power distribution unit 120, and the power feeding unit 130 of the array antenna 100 may be arranged on the dielectric substrate 200 and the ground plane 300.

The radiator 110 includes a plurality of radiating elements 111 and a feed line 112 connecting the plurality of radiating elements in series, and the array antenna 100 according to an embodiment includes a plurality of radiating parts 110. Can contain dogs. The radiator 110 may be printed in the form of a micro strip, and the radiation conductance (G _R ) of each radiating element 111 may be adjusted according to various requirements regarding antenna design such as gain and side lobe level characteristics. have. The feed line 112 of the radiating unit 110 may control the inclination of the beam to be emitted by adjusting the phase of the current input to each radiating element 111. The feed line 112 may be a line having an impedance of a predetermined magnitude, and the impedance of the line according to an embodiment may be 100 ohm.

The power divider 120 includes a first power divider 121, a second power divider 122, and a third power divider 123. The power distributor 120 may transfer the power provided from the power supply unit 130 to the radiator 110. In this case, the first power divider 121 operates as an equal power divider having a constant output power ratio (for example, -3 dB), and the second power divider 122 and the third power divider 123 are each The radiator 110 may operate as an uneven power divider for distributing power of different sizes. In addition, the second power distributor 122 and the third power distributor 123 may match the impedance of the radiator 110 with respect to the power supply unit 130. According to one embodiment, an equal Wilkinson power divider may be used as the first power divider 121 and an uneven Wilkinson power divider as the second power divider 122 and the third power divider 123. Can be used.

The power supply unit 130 may transmit power to be provided to the radiator to the power distribution unit 120. In one embodiment, the power supply unit 130 may be changed into various types of power supply such as a coaxial line or a coplanar wavequide (CPW) using a transition structure.

2 is a diagram illustrating a radiator included in an array antenna according to an exemplary embodiment.

The plurality of radiating elements 111 included in the radiating unit 110 according to an exemplary embodiment are arranged in series in the y direction, and the largest radiating element positioned at the center of the plurality of radiating elements 111 has the largest size and the center. At both ends, the size of the radiating element decreases. In this case, the size of each radiating element 111 may be determined according to the radiating conductance. That is, a large radiating element may have a large radiating conductance compared to a small radiating element. Since the array antenna according to an embodiment may be manufactured in a form printed on a dielectric substrate, each radiating element may be sized as a plane having an x-direction length (width) and a y-direction length (length). Referring to FIG. 2, the radiator 110 according to an exemplary embodiment includes nine radiating elements E1 to E9, and the number of radiating elements may be determined according to the purpose of using the array antenna according to an exemplary embodiment. have.

Radiation conductance of the plurality of radiating elements 111 included in the radiating unit 110 according to an embodiment may be determined according to an array function having low side lobe level characteristics. In one embodiment, the Chebyshev array function with a y direction (vertical) side lobe level of -20 dB was used to determine the radiated conductance. In this case, the angle at which the beam is inclined for the forward (+ z direction) directivity characteristic of the array antenna 100 may be designed to 0 degrees with respect to the z axis.

Equation 1 is an array factor (AF) of the array antenna 100 according to an embodiment, and the magnitude of the current applied to each of the radiating elements 111 may be calculated through Equation 1 and the Chebyshev array function. Can be.

In Equation 1, i is a current applied to each radiating element 111, and AF is a function of Ψ. Equation 2 represents Ψ. If Equation 1 is developed, 15 terms may be calculated as in Equation 3 below.

In Equation 2, k is the wave number of the beam (k = 2π / λ), and d is an interval between the radiating elements 111 and may be defined as 1/2 of the wavelength of the beam (d = λ / 2). Accordingly, the length of the feed line (microstrip line) 112 connecting each radiating element may be designed to be a half wavelength (λ / 2) of the beam. At this time, the phase of the current input to each radiating element is 0 degrees, the phase of the current in each radiating element can be adjusted according to the radiation angle of the beam required according to the use environment. In addition, the number, gain or beam width of the radiating elements can also be adjusted as appropriate. Equation 4 below is an expression of the expansion of Equation 1, and Equation 5 is an 8th order Chebyshev array function.

By comparing the coefficients of the cos term in equations (4) and (5), equation (6) can be obtained.

In this case, x ₀ in Equation 5 is a coefficient R (R = 10 ^{- SLL / 20} , one that can be determined according to the number of radiating elements M (M = 2N + 1, N = 4 in one embodiment) and the side lobe level. In the embodiment, since the side lobe level applied in the vertical direction is -20 dB, it may be determined according to Equation 7 below by R = 10 ^{-(-20) / 20} = 10).

Referring to Equation 6, since M = 9 and R = 10 in one embodiment, x ₀ is 1.0708. Finally, if x ₀ is substituted into Equation 5, the magnitude of the current applied to each radiating element 111 may be calculated as Equation 8.

In Equation 8, i _0n , i _1n , i _2n , i _3n, and i _4n represent current magnitudes normalized based on the current magnitude of i ₀ . At this time, in one embodiment, the current magnitude normalized for each radiating element 111 is a vertical power feeding coefficient.

Table 1 below shows the power supply coefficient of each radiating element 111 and the conductance of each radiating element 111 according to an embodiment calculated based on the array argument function defined in Equation 1 below. In one embodiment, the feed coefficient of each radiating element may be calculated by comparing coefficients between the coefficient of the cos term of the array argument function of Equation 1 and the coefficient of the Chebyshev array function, and the conductance based on the feed coefficient a _n . Can be calculated. Equation 9 represents the sum of conductances of all radiating elements included in the radiating unit 110.

In Equation 9, the total radiating conductance G _t may be calculated based on the constant of proportionality K and the feed coefficient a _n of each radiating element 111, and in one embodiment, each radiating element The sum of the proportionality constant and the power feeding coefficient of 111 is one. A proportionality constant is obtained based on each power supply coefficient (a _n ) calculated by Equation 1 below.

In addition, when the proportional constant K (0.1784) is used, the normalized radiation conductance of each radiating element 111 may be defined as in Equation 11 below.

In one embodiment, the characteristic impedance of each feed line 112 was determined to be 100 [Ω], so the normalized impedence of the feed line 112 was also set to 100 [Ω].

device	Feed Factor (a n )	Normalized conductance	Calculated Value		Optimal value
			Width (mm)	Length (mm)	Width (mm)	Length (mm)
E1	0.6014	0.0645	1.123	3.182	1.523	3.182
E2	0.6153	0.0675	1.173	3.173	1.573	3.173
E3	0.8121	0.1176	1.998	3.065	2.398	3.065
E4	0.9503	0.1611	2.703	3.011	3.503	3.011
E5	1.0000	0.1784	2.982	2.994	4.582	2.994
E6	0.9503	0.1611	2.703	3.011	2.903	3.011
E7	0.8121	0.1176	1.998	3.065	1.798	3.065
E8	0.6153	0.0675	1.173	3.173	0.973	3.173
E9	0.6014	0.0645	1.123	3.182	0.923	3.182

Referring to Table 1, the radiating element according to an embodiment has been optimized in width and length to increase the gain of the array antenna.

3 is a diagram illustrating a power distribution unit according to an exemplary embodiment.

The power distribution unit 120 according to an embodiment may distribute power of different sizes to each of the radiation units 110. The Chebyshev arrangement having the side lobe level of -30 dB in the horizontal direction is the amount of power distributed from the second power distributor 122 and the third power distributor 123 of the power distributor 120 to the radiator 110 in the horizontal direction. It can be calculated based on a function. At this time, the side lobe level in the horizontal direction may be determined as a size that can improve the detection performance in the horizontal direction.

Referring to FIG. 3, the power divider 120 includes a first power divider 121, a second power divider 122, and a third power divider 123-1, 123-2, 123-3, 123-4). The power distributor 120 may distribute the power provided from the power supply unit 130 to apply currents i _x1 to i _x8 to each radiator 110 of the array antenna 100.

The first power divider 121 may operate as an equal power divider that outputs a constant power using the resistor R ₀ .

The second power distributor 122 may output different power to each of the third power distributors 123-1, 123-2, 123-3, and 123-4.

The third power distributors 123-1, 123-2, 123-3, and 123-4 may operate as non-uniform power dividers for distributing power of different sizes to the radiators 110. In this case, the third power distributors 123-1, 123-2, 123-3, and 123-4 are resistors R ₁ to R ₄ and symmetrically arranged impedances Z _1R , Z ' _1R , Z _1L. , Z ' _1L , Z _2R , Z' _2R , Z _2L , Z ' _2L , Z _3R , Z' _3R , Z _3L , Z ' _3L , Z _4R , Z' _4R , Z _4L , Z ' _4L ) . That is, the n th unit 123-n of the third power divider is connected to the n th unit 123-n using the resistors R- _n and impedances Z _nR , Z ' _nR , Z _nL, and Z' _nL . Power may be provided to the quadrant 110.

In the same manner as the method of calculating the magnitude of the current applied to each of the radiating elements 111 arranged in the vertical direction, the magnitude of the current applied to each of the radiating parts 110 in the horizontal direction (that is, the horizontal feeding coefficient) is calculated. When the calculation is performed using Equation 12, a horizontal power feeding coefficient may be obtained as shown in Equation 13.

In addition, the feed coefficients for the respective radiating elements included in the array antenna 100 according to an embodiment, which are calculated using the vertical feed coefficient of Equation 8 and the horizontal feed coefficient of Equation 13, are shown in Table 2 below. same.

E9	0.1750	0.1908	0.2741	0.3619	0.4465	0.5194	0.5730	0.6014
E8	0.1791	0.1952	0.2804	0.3703	0.4568	0.5314	0.5863	0.6153
E7	0.2363	0.2577	0.3701	0.4887	0.6029	0.7014	0.7738	0.8121
E6	0.2765	0.3015	0.4330	0.5718	0.7055	0.8207	0.9054	0.9503
E5	0.2910	0.3173	0.4557	0.6018	0.7424	0.8637	0.9528	1.0000
E4	0.2765	0.3015	0.4330	0.5718	0.7055	0.8207	0.9054	0.9503
E3	0.2363	0.2577	0.3701	0.4887	0.6029	0.7014	0.7738	0.8121
E2	0.1791	0.1952	0.2804	0.3703	0.4568	0.5314	0.5863	0.6153
E1	0.1750	0.1908	0.2741	0.3619	0.4465	0.5194	0.5730	0.6014
	8	7	6	5	4	3	2	One

Referring to Table 2, the feed coefficients of the respective radiating elements 111 are shown, the normalized vertical feed coefficient of Equation 8 is applied to the vertical direction, and the horizontal feed coefficient of Equation 13 is applied to the horizontal direction. Applied. For example, the feeding factor 0.5194 of the radiating element corresponding to E1 in three rows is 0.6014 times the feeding factor 0.8637 of the radiating element corresponding to E5 in three columns, and the feeding coefficient of the radiating element in eight rows among the radiating elements corresponding to E5 in each row. 0.2910 is 0.1750 / 0.6014 times the feed coefficient of the radiating element of one row.

In addition, the third power distribution unit 123 distributes power having different sizes in the horizontal direction according to Equation 13, and impedances Z _iR , Z _iL , and Z of the elements included in the third power distribution unit 123. ' _iR , Z' _iL and R) may be calculated based on Equation 14 below.

Referring to Equation 14, Z ₀ is a predetermined impedance constant, and k represents a ratio of non-uniform power. In one embodiment Z ₀ is set to 50 ohms. K and impedance of the third power distribution unit 123 according to an embodiment are shown in Table 3 (k and impedance of the first third power distribution unit 123-1), Table 4 (second third power distribution unit) K and impedance of 123-2), Table 5 (k and impedance of the third third power distribution unit 123-3), and k of Table 6 (fourth third power distribution unit 123-4) And impedance).

k	1.0245
Z 1R	69.03 [Ω]
Z 1L	49.40 [Ω]
Z ' 1R	72.45 [Ω]
Z ' 1L	50.61 [Ω]
R 1	100.03 [Ω]

k	1.0786
Z 2R	65.65 [Ω]
Z 2L	48.14 [Ω]
Z ' 2R	76.37 [Ω]
Z ' 2L	51.93 [Ω]
R 2	100.29 [Ω]

k	1.1491
Z 3R	61.84 [Ω]
Z 3L	46.64 [Ω]
Z ' 3R	81.64 [Ω]
Z ' 3L	53.60 [Ω]
R 3	100.97 [Ω]

k	1.0442
Z 4R	67.75 [Ω]
Z 4L	48.93 [Ω]
Z ' 4R	73.87 [Ω]
Z ' 4L	51.09 [Ω]
R 4	100.09 [Ω]

The array antenna 100 according to an exemplary embodiment may perform centralized monitoring on a specific sensing area by sharply forming a beam through a high gain and a narrow 3dB radiation angle characteristic (HPBW _3dB = 4.0 °). In addition, the array antenna according to an embodiment achieves low sidelobe levels (-30 dB and -20 dB, respectively) in the horizontal and vertical directions based on the Chebyshev array function to ensure uniform sensing performance in the horizontal and vertical directions. can do. By adjusting the phase of the current input to each radiating element from the array antenna 100 according to an embodiment, a beam having various inclinations may be formed in all directions, and the width of the beam is controlled by adjusting the number of radiating elements. can do. In addition, it is possible to facilitate feeding of each radiating element based on various functions, and there is an advantage in mass production because of the printed structure.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

Claims (15)

1. At least one radiating part including a plurality of radiating elements and a feed line connecting the plurality of radiating elements, and

   A power distribution unit for distributing power provided from a feeder at a first rate to the at least one radiating unit

   Array antenna comprising a.
2. In claim 1,

   And the first ratio is determined based on an array function associated with a side lobe level in a first direction that is perpendicular to the direction in which the plurality of radiating elements are arranged.
3. In claim 1,

   And an conductance of a first radiating element located at the center of the radiating part of the plurality of radiating elements is greater than a conductance of at least one second radiating element located at an edge of the radiating part of the plurality of radiating elements.
4. In claim 3,

   And conductance of the plurality of radiating elements decreases at a second rate in a second direction from the first radiating element to the at least one second radiating element.
5. In claim 4,

   And the second ratio is a ratio determined based on an array function related to the side lobe levels in the second direction.
6. In claim 2,

   And the array function is a chebyshev array function.
7. In claim 1,

   And the sizes of the plurality of radiating elements decrease at a second rate in a second direction from the first radiating element to the at least one second radiating element.
8. In claim 7,

   And the second ratio is a ratio of a feed factor determined based on an array factor function of the array antenna and an array function related to the side lobe level in the second direction.
9. In claim 8,

   The power feeding coefficient is an array antenna determined by comparing coefficients between the array function and the array function.
10. In claim 1,

    A dielectric substrate having the at least one radiating portion printed in a patch form

    Array antenna further comprising a.
11. In claim 1,

    The feed line, the array antenna for controlling the phase of the current input to the plurality of radiating elements.
12. In claim 1,

    The feed line is an array antenna for connecting the plurality of radiating elements in series.
13. In claim 1,

    And the power distribution unit matches an impedance of the at least one radiation unit with respect to the power supply unit.
14. In claim 1,

    The power distribution unit,

    At least one first power distribution unit providing power distributed at the first ratio to the at least one radiating unit, and

    A second power divider configured to provide the same amount of power provided from the feeder to the at least one first power divider;

    Array antenna comprising a.
15. In claim 1,

    The impedance of the first power divider is determined in accordance with the first ratio and a predetermined impedance constant.

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