JP2007074206A - Microstrip array antenna - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the directive characteristics of a microstrip array antenna. <P>SOLUTION: The microstrip array antenna 100 having the small number of lines has four antenna element lines and power is supplied from three feeding strip lines 41, 42, 43. In radial antenna elements 5-61 to 5-67 and radial antenna elements 5-91 to 5-97, radial ends are formed from the feeding strip lines 41, 43 to the inside of the antenna, respectively. Power is supplied to twenty-eight radial antenna elements in phase and individual radiant quantities of the radial antenna elements 5-71 to 5-77 and 5-81 to 5-87 connected to the center feeding strip line are set twice the individual radiant quantities of the radiant antenna elements 5-61 to 5-67 and 5-91 to 5-97. Consequently, the low side lobe of the antenna can be achieved. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a planar array antenna using a dielectric substrate that can be used for transmission and reception antennas of various radio wave sensors such as automobile-mounted radars.

  In recent years, millimeter-wave antennas used for high-capacity high-speed communication and automobile radar have been developed. Among various millimeter-wave antennas, a microstrip array antenna (hereinafter sometimes abbreviated as “MSAA”) is advantageous for low cost and thinning.

  Conventionally, the MSAA in the left and right alternate arrangement with respect to the main line (feeding strip line) is configured with the same radiation amount and the same radiation phase in the right antenna element row and the left antenna element row, so when the number of antenna rows is small Because of the low degree of freedom in the radiation distribution, directivity control was difficult.

Nevertheless, in order to control the directivity, in order to increase the degree of freedom of the radiation amount distribution, the number of antenna columns must be increased, and there is a drawback that the antenna is enlarged.
JP 2001-44752 A

  In Patent Document 1 and other microstrip array antennas, when the number of columns of the array antenna is small, the radiation amount given to each column and the degree of freedom of the radiation phase are small, which limits the feasible directivity pattern. There's a problem. That is, if the number of radiating antenna elements constituting each antenna element row is increased, the beam width in the direction of the feed strip line can be easily reduced, and if the number of antenna element rows is increased, the beam strip is perpendicular to the feed strip line. The beam width in the direction can be easily reduced. Then, when the number of antenna element rows is 2 or 3, a microstrip array antenna (planar antenna) having a wide beam width in the direction perpendicular to the feeding strip line is obtained.

  The above problems are specifically as follows. The configuration shown in FIG. 1 of Patent Document 1 is assumed to be a subarray, and for example, an MSAA including two subarrays branched from a feeding point is considered.

  The first problem is that if each subarray has a substantially symmetrical radiated electric field, that is, if both of the antenna element arrays connected to both sides of the feed stripline are symmetric subarrays, There is a problem that the side lobe level in the directivity pattern in the direction orthogonal to the longitudinal direction (in the horizontal plane when the feeding strip line is arranged vertically) is large (for example, about -11 dB).

  The technical reason for this problem is that the subarray is usually designed on the assumption that the radiation amplitude levels of the antenna element arrays arranged on both sides of the feeding strip line are equal. For this reason, the amplitude distribution in the plane orthogonal to the longitudinal direction of the feed strip line is formed as a “uniform” amplitude distribution by a total of four antenna element arrays of two subarrays, which is effective in reducing side lobes. This is because a “taper-like” amplitude distribution that is high at the center and low at the outside cannot be realized.

  As a second problem, in the microstrip array antenna composed of two subarrays, the direction of the main beam in the directivity pattern in the plane perpendicular to the longitudinal direction of the feed strip line is changed from the normal direction of the planar antenna to the above-mentioned plane. When trying to tilt, the side lobe level (for example, -11 dB) existing in the case of the front beam is remarkably increased (for example, becomes -2 to -3 dB).

  The technical reason for the problem is that the subarray is usually designed on the assumption that the radiation phases of the antenna element arrays arranged on both sides of the feeding strip line are equal. For this reason, when there are two feed strip lines, the phase difference between the two feed strip lines depending on the position of the branch point (more precisely, the radiating antenna element closest to the branch point of each of the two sub-arrays and the branch point) This is because the horizontal phase distribution is partly stepped and the “constant gradient distribution” cannot be realized.

  The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to reduce the side lobes with respect to the vertical direction of the longitudinal direction of the feed strip line in a microstrip array antenna with a simple configuration. .

  In order to solve the above problems, the means according to claim 1 is a microstrip formed of a dielectric substrate having a conductor ground plate formed on the back surface and a strip conductor formed on the dielectric substrate. In the array antenna, the strip conductor includes a plurality of linearly arranged feed strip lines and a plurality of connection strips arranged from the sides at predetermined intervals along at least one side of both sides of the feed strip line. A plurality of subarrays each formed of a strip-shaped radiating antenna element, and a branch line for feeding power to the plurality of subarrays from one feeding point. The longitudinal directions of the feeding striplines of each subarray are mutually The two subarrays that are parallel and located on the outer periphery are connected to the radiating antenna element on only one side of the feed strip line, and the other subarray. Is both sides of the feeding strip line, radiating and antenna elements are sequentially connected alternately, wherein the electric field direction of emission of all the radiating antenna element is parallel.

  According to the second aspect of the present invention, the radiating end of the radiating antenna element of the sub-array located on the outer periphery is formed from the feed strip line connected to the radiating antenna element toward the inside of the microstrip array antenna. It is characterized by.

  The degree of freedom in giving the vertical amplitude distribution or phase distribution of the feed strip line is limited by the number of feed lines. According to the present invention, it is possible to increase the number of feed lines while keeping the total number of radiating antenna elements the same, and the degree of freedom of independently controlling the amplitude distribution and the phase distribution is improved. Using this, (1) when the main beam is front (normal direction of the planar antenna), the side lobe can be reduced by making the amplitude distribution into a mountain-shaped (taper-like) distribution, and (2) the main beam When the beam is tilted, the side lobes can be reduced by bringing the phase distribution closer to a linear distribution with a constant gradient.

  Thus, according to the present invention, side lobes can be reduced as compared with the prior art. The effect is obtained not only when (1) the main beam is front (tapering of the amplitude distribution) but also (2) when the main beam is tilted (linearization of the phase distribution).

  Hereinafter, specific examples of the present invention will be described with reference to the drawings. Each figure only shows the outline of the characteristic part of the present invention, and the position of the connection point, the width of each radiating antenna element, and the like should be designed based on known design examples as appropriate.

  FIG. A is a plan view showing a configuration of a microstrip array antenna 100 according to a specific embodiment of the present invention. In addition, FIG. B is a side view thereof. On the other hand, FIG. FIG. 2A is a plan view showing a configuration of a microstrip array antenna 900 having a conventional structure, and FIG. B is a side view thereof.

  In the microstrip array antenna 100 according to the present invention shown in FIG. 1, a strip conductor 2 is formed on the surface of a dielectric substrate 1, and a ground plate 3 made of a conductor is formed on the back surface. The strip conductor 2 includes a three-branch branch line 40 having a feed point 20, feed strip lines 41, 42 and 43 connected to the branch line 40, and a total of 28 radiating antenna elements. The radiating antenna elements 5-61 to 5-67 are connected to the feed strip line 41. The radiating antenna elements 5-71 to 5-77 and 5-81 to 5-87 are connected to the feeding strip line 42. The radiating antenna elements 5-91 to 5-97 are connected to the feed strip line 43. The 28 radiation antenna elements have a strip shape (rectangular shape) and are directly connected to the feeding strip lines 41, 42 and 43. The radiation antenna element 5-ij is collectively referred to as “antenna element array i” for each i.

  Specifically, a feeding strip line 42 is connected to the center of the three-branching branch line 40, and feeding strip lines 41 and 43 are connected to both ends of the branch line 40. The linear feed strip lines 41, 42 and 43 are parallel to each other. The radiating antenna elements 5-61 to 67 connected to the feeding strip line 41 have their radiating ends facing the feeding strip line 42 side. The radiating antenna elements 5-71 to 77 connected to the feeding strip line 42 have their radiating ends facing the feeding strip line 41, and the radiating antenna elements 5-81 to 87 have their radiating ends fed to the feeding strip line. It faces the 43 side. The radiation antenna elements 5-91 to 97 connected to the feed strip line 43 have their radiation ends directed toward the feed strip line 42. The feeding strip line 41 and the radiating antenna elements 5-61 to 67 constitute a sub-array SA1, the feeding strip line 42, the radiating antenna elements 5-71 to 77 and the 5-81 to 87 constitute a sub-array SA2, and the feeding strip line 43 The radiating antenna elements 5-91 to 97 constitute a sub-array SA3.

  In the microstrip array antenna 100 of FIG. 1, the longitudinal directions of the feeding strip lines 41, 42, and 43 are parallel to each other, and the radiating antenna elements 5-61 to 67, 5, 5 each having a strip shape (rectangular shape). The longitudinal direction (the direction of the radiated electric field) of −71 to 77, 5-81 to 87, and 5-91 to 97 is perpendicular. If the longitudinal directions of the radiating antenna elements 5-61 to 67, 5-71 to 77, 5-81 to 87, and 5-91 to 97 are all parallel to each other, they are fed to the feeding strip. The present invention can be applied regardless of the angle formed with the longitudinal direction of the lines 41, 42 and 43.

  The three-branch branch line 40 distributes power to the feeding strip lines 41, 42, and 43 as follows. That is, the three-branch branch line 40 connects the power input from the feeding point 20 to the feeding strip lines 41 and 43 to which the seven radiating antenna elements are connected, respectively, 1/6 and 14 radiating antenna elements. 2/3 is supplied to the feeding strip line 42. Each sub-array is designed so that the same power is radiated from all the radiating antenna elements. Eventually, the individual radiation from the 14 radiating antenna elements 5-61 to 5-67 and 5-91 to 97 is achieved. The amount of each radiation from the 14 radiation antenna elements 5-71 to 5-77 and 5-81 to 87 is designed to be twice the amount. It is well known that the amount of coupling between each radiating antenna element and the feeding strip line can be designed as a width of each strip shape. In FIG. 1, for the purpose of “schewing the outline”, for example, the antenna element radiating antenna elements 5-61 to 67 are simply indicated by “same width” where they should originally be strips having different widths. That is, FIG. 1 only shows that the radiated electric fields of the radiating antenna elements connected to the same feeding strip line are all equal, and “the geometric shapes of all the radiating antenna elements match”. Does not mean.

  The three-branch branch line 40 supplies power to the feed strip lines 41, 42, and 43 so that electromagnetic waves having the same phase are radiated from all 28 radiation antenna elements. That is, with respect to the transmission distance from the feeding point 20 to the radiating antenna element 5-71 connected to the feeding strip line 42 closest thereto, the feeding distance from the feeding point 20 to the radiating antenna element 5-81 connected to the feeding strip line 42 is increased. The transmission distance is obtained by adding ½ times the guide wavelength λ in the high-frequency strip conductor to be used. Further, the transmission distance from the feeding point 20 to the radiating antenna element 5-61 connected to the feeding strip line 41 closest thereto is the transmission distance from the feeding point 20 to the radiating antenna element 5-81 connected to the feeding strip line 42. The transmission distance from the feed point 20 to the radiating antenna element 5-91 connected to the feed strip line 43 nearest to the feed point 20 is connected to the feed strip line 42 by adding the integral multiple of the guide wavelength λ to the distance. The transmission distance to the radiated antenna element 5-71 is added with an integral multiple of the guide wavelength λ. Hereinafter, the adjacent radiating antenna elements 5-ij (j = 1 to 6) and the radiating antenna elements 5-i (j + 1) in each antenna element row (i = 6 to 9) have a transmission distance from the feeding point 20 in the pipe. The wavelength λ was varied. This embodiment is composed of only two sub-arrays SA1 and SA3, symmetrical sub-array SA2 and branch line 40, and the simplest configuration of the invention according to claims 1 and 2 from the aspect of the number of antenna element arrays. It is.

  The conventional microstrip array antenna 900 of FIG. 2 is shown for comparison and has the following configuration. It consists of two branch lines 90 and feed strip lines 91 and 92 each having 14 radiating antenna elements connected thereto. The radiating antenna elements 95-61 to 67 and 95-71 to 77 and the feeding strip line 91 are referred to as a sub-array SA91, and the radiating antenna elements 95-81 to 87 and 95-91 to 97 and the feeding strip line 92 are referred to as a sub-array SA92. The 28 radiation antenna elements of the microstrip array antenna 900 of FIG. 2 are all designed to have the same radiation amount and the same radiation phase. Also in FIG. 2, for the purpose of “schewing the outline”, for example, the antenna element radiating antenna elements 59-61 to 67 should be simply “same width” where they should originally be strips having different widths. FIG. 2 merely shows that the radiated electric fields of the respective radiating antenna elements are all equal, and does not mean that “the geometric shapes of all the radiating antenna elements are the same”.

  FIG. 3 shows the relative radiated electric field strength of each antenna element array of the microstrip array antenna 100 of FIG. 1 according to the present invention and the microstrip array antenna 900 of FIG. 2 having a conventional structure. In addition, the space | interval of the radiation ends of each row | line was made the same. Here, as an example, the case where the radiation end intervals are the same is shown, but this is not a necessary condition for obtaining the effect of the present invention. In the actual design work, the design requirement is the radiating edge spacing to make it closer to the desired directivity pattern, or the radiating edge spacing to improve the antenna aperture efficiency as described in the section of “Other effects” later. It is good to select it in light of it. In the microstrip array antenna 900 of FIG. 2 having a conventional structure, the radiation intensity of each radiation antenna element has a uniform distribution as shown by the black triangles in FIG. On the other hand, the microstrip array antenna 100 of FIG. 1 according to the present invention gives the distribution as shown by the white circles in FIG. The distribution indicated by the white circles is a “taper distribution” that is effective in reducing the side lobes of the directivity pattern in the horizontal plane when the feeding strip lines 41 to 43 are arranged in the vertical direction. In addition, the space | interval of each radiation | emission end was 1.7 mm.

  FIG. 4 shows directivity patterns of the microstrip array antenna 100 of FIG. 1 according to the present invention and the microstrip array antenna 900 of FIG. 2 having a conventional structure. When the normal direction of the microstrip array antenna which is a planar antenna is 0 deg, there are two side lobes each having a peak in the vicinity of ± 60 deg with respect to the main beam in the 0 deg direction. It can be seen that the sidelobe level of the microstrip array antenna 900 having the conventional structure is −11.3 dB, whereas the microstrip array antenna 100 having the proposed structure can reduce the sidelobe level to −23.9 dB. That is, the microstrip array antenna 100 in FIG. 1 can reduce the side lobe by 12 dB or more in the directivity in the plane perpendicular to the longitudinal direction of the feed strip line, compared to the microstrip array antenna 900 in FIG.

  In addition, 14 radiation antenna elements 5-61 to 5-67 (antenna element array 6) and 14-91 to 97 (antenna element array 9) are individually radiated from the 14 radiation antenna elements 5-61 to 5-67 (antenna element array 6). As the individual radiation amounts from 71 to 5-77 (antenna element array 7) and 5-81 to 87 (antenna element array 8) are larger, the side lobe is reduced. This embodiment is remarkable when the number of feeding strip lines is small, particularly when there are three. However, if the radiation amounts of the antenna element array 6 and the antenna element array 9 are too small, the beam width tends to be thick. Therefore, the radiation amount is considered in consideration of both the design requirements for the desired beam width and the design requirements for sidelobe reduction. It is good to choose the distribution.

  Note that there are the following precautions in designing the actual radiating element array. That is, in the case of MSAA in which the radiating antenna elements are partly coupled directly to the feeding strip line, the radiating antenna element spacing when the radiating antenna elements are arranged on both sides of the feeding strip line and the radiating antenna element only on one side of the feeding strip line When the antennas are arranged, it is necessary to change the distance between the radiating antenna elements. This is because when the radiating antenna element is connected to the feed strip line, the phase rotation amount of the radio wave propagating through the feed strip line varies. Normally, the phase of the radio wave propagating through the feeding strip line is advanced by providing the radiating antenna element. Therefore, when the radiating antenna element is provided only on one side, the phase is delayed as compared with the case where it is on both sides. In order to compensate for this, it is necessary to reduce the element spacing. By doing so, the phase in the radiating element group disposed only on one side is aligned, and the phase with the other radiating element groups disposed on both sides is also aligned. By arranging the radiation antenna in the feed line in this way, if the amount of perturbation (element width dependency) of the radio wave propagating through the feed strip line is accurately grasped in advance, the one-side arrangement Phase compensation in MSAA in which the radiating element group and the radiating element group arranged on both sides are mixed is performed well, and a desired phase distribution is realized.

  In FIG. 1, the radiation antenna elements 5-61 to 5-67 and 5-91 to 97 located on the outermost periphery have their radiation ends facing inward with respect to the entire antenna. However, even if their radiation ends are outward, it is possible to obtain the action and effect of improving the degree of freedom of the radiation amplitude distribution.

  When the main beam is tilted from the normal direction of the planar antenna, a microstrip array antenna 200 as shown in FIG. 5 may be configured. The microstrip array antenna 200 of FIG. 5 is obtained by replacing the three-branch branch line 40 having the feeding point 20 of the microstrip array antenna 100 of FIG. 1 with a three-branch branch line 44, and the other configurations are the same. It is. That is, the strip conductor 22 is formed on the surface of the dielectric substrate 1, and the ground plate 3 made of a conductor is formed on the back surface. The strip conductor 22 includes a three-branch branch line 44 having a feeding point 20, feeding strip lines 41, 42 and 43, a total of 28 radiating antenna elements 5-61 to 5-67, 5-71 to 5-77, 5 -81 to 5-87 and 5-91 to 5-97. The feeding strip line 41 and the radiating antenna elements 5-61 to 67 constitute a sub-array SA1, the feeding strip line 42, the radiating antenna elements 5-71 to 77 and the 5-81 to 87 constitute a sub-array SA2, and the feeding strip line 43 The radiating antenna elements 5-91 to 97 constitute a sub-array SA3.

  The branch line 44 of the microstrip array antenna 200 of FIG. 5 differs from the branch line 40 of the microstrip array antenna 100 of FIG. 1 in the following points. That is, the branch line 44 of the microstrip array antenna 200 of FIG. 5 is longer than the branch line 40 of the microstrip array antenna 100 of FIG. 1 by the distance from the feeding point to the subarray SA1, and from the feeding point to the subarray SA3. Is shorter than the branch line 40 of the microstrip array antenna 100 of FIG. Thus, the radiating antenna elements 5-71 to 5-77 and 5-81 to 5-87 of the sub-array SA2 all radiate electromagnetic waves in the same phase, but the radiating antenna elements 5-61 to 5-67 of the sub-array 1 do so. And the phase of the radiating antenna elements 5-91 to 5-97 of the sub-array SA3 is further advanced.

  The relative radiation phase of each antenna element array of the microstrip array antenna 200 of FIG. 5 designed as described above is shown by white circles in FIG. In addition, the space | interval of the radiation ends of each row | line | column was the same, and the space | interval was 1.7 mm. Here, as an example, the case where the radiation end intervals are the same is shown, but this is not a necessary condition for obtaining the effect of the present invention. In actual design work, the distance between the radiating edges to make it closer to the desired directivity pattern, or the distance between the radiating edges to increase the antenna aperture efficiency as described in the section “Other effects”, is checked against the design requirements. It is good to choose. If the phases of the radiating antenna elements 5-71 to 5-77 (antenna element array 7) and 5-81 to 5-87 (antenna element array 8) of the subarray SA2 are 0 degrees, the radiating antenna elements 5-61 of the subarray SA1 are set. 5 to 67 (antenna element array 6) has a phase of -89 degrees, and the radiation antenna elements 5-91 to 5-97 (antenna element array 9) of the subarray SA3 have a phase of +89 degrees. As a result, a main beam inclined by 20 degrees from the normal direction of the planar antenna toward the subarray SA3 can be formed. A design in which the two-branch branch line 90 of the microstrip array antenna 900 of FIG. 2 is replaced is also indicated by a black triangle in FIG. This can be achieved by replacing the bifurcated branch line so that the relative radiation phases of the subarray SA91 and the subarray SA92 are different by 134.8 degrees.

  FIG. 7 shows the directivity pattern in the plane perpendicular to the longitudinal direction of the feed strip line for the present embodiment shown by white circles in FIG. 6 and the two-branch comparative example shown by black triangles. In this example and the comparative example, the inclination of the main beam can be realized as 20 degrees. At this time, side lobes exist in the vicinity of −30 degrees on the opposite side to the tilted direction. The side lobe level is −2.4 dB in the comparative example, but according to the present embodiment, it becomes −21.8 dB, and an improvement of 19.4 dB is obtained. That is, in the case of microstrip array antennas in which the radiation phase is uniform in the sub-array and the radiation phase is made different between the sub-arrays, all the conventional sub-arrays have radiation antenna elements on both sides. When the outer peripheral sub-array has a radiating antenna element on only one side, side lobes can be reduced.

[Other effects]
The effectiveness of the present invention will be described from the viewpoint of the area of the antenna. FIG. 8 shows an interval necessary for avoiding coupling with adjacent antenna element rows or coupling with a feeding strip line when four antenna element rows are arranged.

  FIG. A indicates that the feeding strip lines are arranged in all the antenna element rows, and it is necessary to secure the minimum distance α at the radiation end of each antenna element row in order to avoid coupling with the adjacent feeding strip line. In this case, there is a useless area of width 3α in the antenna area. FIG. In B, the feeding strip lines are respectively arranged on the outermost antenna element rows, and the two antenna element rows are connected to one feeding strip line. In this case, the outermost antenna element array is formed from the feeding strip line toward the outer periphery of the antenna. In this case, there is a useless area having a width 2α in the antenna area. FIG. B corresponds to the invention according to claim 1 excluding claim 2 of the present application. FIG. In C, a feeding strip line is arranged on each outermost antenna element row, two antenna element rows are connected to one feeding strip line, and the outermost antenna element row is directed from the feeding strip line toward the inside of the antenna. The case where it was formed is shown. In this case, it is necessary to secure the minimum distance β for avoiding coupling of the radiation ends of the antenna element arrays facing each other. In this case, there is a useless area having a width of 2β in the antenna area. FIG. C corresponds to the invention according to claim 2 of the present application. FIG. D is a structure in which two antenna strips are connected with two feeding strip lines. In this case, there is a useless area of width β in the antenna area.

  Usually α is greater than β. This is because the radiating ends of the radiating antenna elements facing each other are not directly opposed to each other but are designed to be “shifted in the vertical direction”. Figure 8 shows the efficiency of the antenna area. D is the best, FIG. C (Claim 2 of the present application), FIG. B (other than claim 2 of the present application), FIG. Area efficiency decreases in the order of A. However, FIG. FIG. As described above, C is preferable from the viewpoint of reducing side lobes. Further, the outermost periphery of the array antenna is not significantly affected by the ground plate on the back surface, and it is desirable that the radiation end of the radiation antenna element is not brought close to the outer periphery of the dielectric substrate. From this point of view, FIG. A, FIG. B, FIG. In each of D, the radiation end of the radiation antenna element arranged on the outermost periphery is directed to the outer periphery of the dielectric substrate. It can be seen that only C (Claim 2 of the present application) has a configuration that can sufficiently secure a gap from the outer periphery of the dielectric substrate to the radiation end. 4 and 7 are directivity pattern diagrams based only on the array factor, excluding so-called element factors.

  In all the embodiments described above, each radiating antenna element may be inclined from the vertical direction of the longitudinal direction of the feeding strip line. In that case, as described in Patent Document 1, each radiating antenna element may have a rectangular shape, and may be connected at only one vertex thereof, or may be electromagnetically coupled by providing a minute gap.

  Various radiation characteristics (low side lobe, main radiation (main beam)) required for applications that require small array antennas, such as for short-range sensors for automobiles and subarrays for directivity formation (DBF) by digital signal processing An antenna with direction control) can be realized.

The top view (1.A) and side view (1.B) which show the structure of the microstrip array antenna 100 which concerns on the specific 1st Example of this invention. The top view (2.A) and side view (2.B) which show the structure of the microstrip array antenna 900 of the conventional structure. The graph which shows the radiation | emission amount for every antenna element row | line | column of the microstrip array antenna 100 and the microstrip array antenna 900. FIG. The graph which showed the directivity pattern of the microstrip array antenna 100 of 1st Example compared with the directivity pattern of the microstrip array antenna 900. FIG. The top view (5.A) and side view (5.B) which show the structure of the microstrip array antenna 100 which concerns on the specific 2nd Example of this invention. The graph which shows the relative radiation | emission phase of each antenna element of the microstrip array antenna 200. FIG. The graph which showed the directivity pattern of the microstrip array antenna 200 compared with the directivity pattern of what replaced the branch line of the microstrip array antenna 900. FIG. The top view which shows the four kinds of structure methods of the microstrip array antenna which has four antenna element rows.

Explanation of symbols

1: Dielectric substrate 100, 200: Microstrip array antenna 2, 22: Strip conductor 20: Feed point 3: Ground plate made of conductor 40, 44: Branch line 41, 42, 43: Feed strip line 5-ij, ( i = 6-9, j = 1-7): radiating antenna elements SA1, SA2, SA3: subarrays

Claims (2)

In a microstrip array antenna formed from a dielectric substrate having a conductor ground plate formed on the back surface and a strip conductor formed on the dielectric substrate,
The strip conductor is
A plurality of strip-shaped radiating antenna elements connected and arranged from a side of the feeding strip line arranged in a line at a predetermined interval along at least one side of both sides of the feeding strip line; A plurality of subarrays comprising:
A branch line for feeding power to the plurality of subarrays from one feeding point;
The longitudinal directions of the feeding strip lines of the subarrays are parallel to each other,
The two sub-arrays located on the outer periphery are connected to the radiating antenna element on only one side of the feeding strip line,
In the other subarray, the radiating antenna elements are alternately connected to both sides of the feeding strip line in order,
A microstrip array antenna characterized in that the electric field directions radiated by all the radiating antenna elements are parallel. The radiation end of the radiation antenna element of the subarray located on the outer periphery is formed from the feed strip line to which the radiation antenna element is connected toward the inside of the microstrip array antenna. The microstrip array antenna described in 1.