Search

EP-4307482-B1 - ARRAY ANTENNA

EP4307482B1EP 4307482 B1EP4307482 B1EP 4307482B1EP-4307482-B1

Inventors

  • SATO, KEISUKE
  • SUZUKI, YUSUKE
  • AMAKAWA, Eiji

Dates

Publication Date
20260506
Application Date
20220309

Claims (7)

  1. An array antenna (1) comprising a plurality of elements (100, 100A) and configured to transmit and receive electromagnetic waves via the elements (100, 100A), comprising: an electromagnetic wave control unit (2), configured to incline the direction of transmission and reception of electromagnetic waves in at least a first direction by emitting electromagnetic waves of mutually different amplitudes or mutually different phases at the plurality of elements (100, 100A), wherein the array antenna (1) has a plurality of element columns (110, 110A) in which two or more N elements are aligned at a prescribed interval d1 in a second direction substantially orthogonal to the first direction, the element columns (110, 110A) are configured as sub arrays, the elements (100, 100A) are arranged with a prescribed interval d2 therebetween in the first direction to form element rows (120), and the element columns (110, 110A) are disposed offset in the first direction by substantially d2/2 from elements or element columns adjacent thereto in the second direction, characterized in that : the element column in the outermost element row has more elements than any other element column in the element row other than the outermost element row.
  2. The array antenna according to claim 1, wherein the element columns (110, 110A) in the element rows outside a predetermined center position has the number of elements equal to or greater than the number of the elements in any other element column in the element row on the center position side.
  3. The array antenna (1) according to claim 1, wherein the array antenna (1) has an array group on the outermost side in the first direction, and the array group has a plurality of the element rows in the first direction.
  4. The array antenna (1) according to claim 1, wherein the array antenna (1) has a plurality of array groups outside in the first direction, and the array group has a plurality of rows of the elements in the first direction, and in the first direction, an outer array group has a number of the element rows greater than or equal to those of inner array group.
  5. Array antenna (1) according to claim 2, wherein the element row which has the least element has one said element.
  6. The array antenna (1) according to claim 1, wherein said d2 is approximately λ/2 and said d1 is 0.5λ or more where λ is the wavelength of the electromagnetic wave to be transmitted and received.
  7. The array antenna (1) according to claim 1, wherein the array antenna (1) is a base station antenna or a relay antenna of a mobile terminal, and the first direction is substantially horizontal.

Description

Technical Field The present invention relates to an array antenna having a plurality of elements and transmitting and receiving radio waves via the elements. Background Art Conventionally, a base station for a mobile terminal or the like forms a wide-angle area with a sector beam having a beam width of about 90 degrees or about 120 degrees. On the other hand, in 5G, from the view point of improving area quality, there are cases where it is required to steer a narrow high-gain beam with a beam width of 20 degrees or less at wide angle for the sake of simultaneously satisfying both high gain of the antenna and wide-angle area formation. FIG. 21 shows a configuration example of the base station 5 and the relay device 6. Beam #6 and beam #2 are directed from base station 5 toward mobile terminals 701 and 702. On the other hand, the beam is directed via the relay device 6 to the portable terminal 703 behind the building. In order to realize this configuration, in mobile communications, the development of high-performance antennas that support digital beamforming using multiple devices and analog beamforming using beamforming ICs is underway. A triangular arrangement as shown in FIG. 23 is known as an arrangement of array antennas that maximizes beamforming performance (see paragraph 0002 and FIG. 27, etc. of Patent Literature 1). With this arrangement, the best beamforming performance can be obtained by appropriately setting the element spacing and freely setting the feeding conditions for each element. In a case where the amplitude and phase of all the arranged antenna elements are variable, that is, if they can be adjusted freely, the "triangular arrangement" of the antenna arrangement is desirable for antenna gain and for angle range of beam steering, considering the side lobe characteristics, etc. For example, Patent Literature 2 describes that, in the case of a planar array of equilateral triangular arrangement, the distance d between element antennas of a two-element partial array is the same regardless of the combination of two element antennas in any direction (see paragraph 0064). Hereinafter, a phased array antenna and a beamforming antenna are sometimes simply referred to as an array antenna or an antenna. Also, an antenna element may be simply called an element. US 2018/309210 A1 discloses an array antenna that can perform beam steering in both an azimuth direction and an elevation direction, can suppress an increase in the number of targets to be subjected to phase shift control, and that can obtain high antenna gain. The antenna includes: a plurality of sub-arrays that each include a plurality of radiating elements and are two-dimensionally arranged in a first direction and a second direction, which are perpendicular to each other; and a plurality of power feeding lines that individually feed power from a high-frequency input/output device to the plurality of sub-arrays. The plurality of sub-arrays are arranged along straight lines in the first direction, and are arranged in the second direction such that among two sub-arrays that are adjacent to each other in the second direction, one sub-array is shifted in the first direction with respect to the other sub-array. US 2015/349434 A1 discloses an array antenna for satellite communications and an antenna, in which the side-lobe level and power-supply loss are low. The antenna includes a first sub-array and a second sub-array, each including antenna elements arrayed in a matrix with a regular pitch, the first sub-array and the second sub-array being shifted relative to each other in a satellite orbital direction. US 2015/084832 A1 discloses an antenna array that can reduce energy of side lobes in horizontal beams in an antenna array pattern and improve ultra-wideband performance. The antenna includes at least two antenna sub-arrays, where the at least two antenna sub-arrays are arranged in a vertical direction, each of the antenna sub-arrays includes multiple radiating elements, and in at least two adjacent antenna sub-arrays in the vertical direction, radiating elements at corresponding positions in the respective antenna sub-arrays are arranged in a staggered manner in a horizontal direction. Prior Art Patent Literature Patent Literature 1Japanese Patent Laid-Open No. 2021-027465Patent Literature 2Japanese Patent Laid-Open No. 2020-198576 Summary of the Invention Problems to be Solved by the Invention First, the difference between a triangular array and a square array is explained. FIG. 22 shows a configuration example of a square array antenna, and FIG. 23 shows a configuration example of a triangular array antenna. In the triangular array shown in FIG. 23, adjacent element rows are horizontally shifted by d/2, so the horizontal element spacing can be considered equivalent to an element spacing of d/2. This configuration improves horizontal beamforming performance compared to the square array. Especially when steering at a wide angle, an increase o