US-12627075-B2 - Compact cross-polarized dipole radiating elements having embedded coupling loops therein

US12627075B2US 12627075 B2US12627075 B2US 12627075B2US-12627075-B2

Abstract

A cross-polarized dipole radiating element includes: (i) a substrate having a quad-arrangement of radiating arms on a forward-facing surface thereof, and a radio-frequency (RF) coupled loop on a rear-facing surface thereof, and (ii) a feed stalk electrically coupled to the quad-arrangement of radiating arms. The RF coupled loop can include a quad-arrangement of rear-facing coupling elements, which extend opposite corresponding ones of the quad-arrangement of radiating arms, and a quad-arrangement of metal traces, which are configured to electrically couple the quad-arrangement of coupling elements together into a closed electrical loop.

Inventors

Cheng Xue
Bo Wu
Ligang Wu
Bin Sun
Jian Zhang
Yuemin Li
Peter J. Bisiules

Assignees

Outdoor Wireless Networks LLC

Dates

Publication Date: 20260512
Application Date: 20230124

Claims (12)

1 . A cross-polarized dipole radiating element, comprising: a substrate having a quad-arrangement of radiating arms formed on a forward-facing surface thereof, and a radio-frequency (RF) coupled loop formed on a rear-facing surface thereof; and a feed stalk electrically coupled to the quad-arrangement of radiating arms, wherein the RF coupled loop comprises: a quad-arrangement of coupling elements, which extend opposite corresponding ones of the quad-arrangement of radiating arms; and a quad-arrangement of metal traces, which are configured to electrically couple the quad-arrangement of coupling elements together into a closed electrical loop, and wherein centroids of the quad-arrangement of coupling elements are located at four corners of a square, when viewed from a plan perspective, and wherein each metal trace in the quad-arrangement of metal traces extends at least partly within the square.
2 . The radiating element of claim 1 , wherein each of the coupling elements in the quad-arrangement have a circular or polygonal shape, when viewed from the plan perspective.
3 . The radiating element of claim 1 , wherein each of the metal traces in the quad-arrangement have a linear or arcuate shape, when viewed from the plan perspective.
4 . The radiating element of claim 1 , wherein a capacitance between each of the coupling elements and a corresponding radiating arm is greater than 0.1 pF.
5 . The radiating element of claim 1 , wherein each of the metal traces has a length in a range between 0.125λ 0 and 0.25λ 0 , where λ 0 corresponds to a wavelength associated with a center frequency of an operating band of the radiating element.
6 . The radiating element of claim 1 , wherein a capacitance between each of the coupling elements and a corresponding radiating arm is greater than 0.1 pF; and wherein each of the metal traces has a length in a range between 0.125λ 0 and 0.25λ 0 , where λ 0 corresponds to a wavelength associated with a center frequency of an operating band of the radiating element.
7 . The radiating element of claim 1 , further comprising a cross-polarized feed signal network electrically coupled to a base of the feed stalk.
8 . The radiating element of claim 1 , wherein the substrate is polygonal-shaped; and wherein the quad-arrangement of radiating arms only partially cover the forward-facing surface of the substrate.
9 . The radiating element of claim 1 , wherein a ratio of an area of each radiating arm relative to an area of a corresponding coupling element is in a range from 6 to 24.
10 . A cross-polarized dipole radiating element, comprising: a substrate having a quad-arrangement of radiating arms on a forward-facing surface thereof, and a radio-frequency (RF) coupled loop on a rear-facing surface thereof, which comprises a quad-arrangement of circular or polygonal-shaped coupling elements that are electrically coupled together and overlap centroids of their respective radiating arms when viewed from a plan perspective; a quad-arrangement of metal traces, which are configured to electrically couple the quad-arrangement of coupling elements together into a closed electrical loop; and a feed stalk electrically coupled to the quad-arrangement of radiating arms, wherein centroids of the quad-arrangement of coupling elements are located at four corners of a square, when viewed from the plan perspective, and wherein centroids of the quad-arrangement of coupling elements are aligned with the centroids of the radiating arms when viewed from the plan perspective.
11 . The radiating element of claim 10 , wherein each of the metal traces has a length in a range between 0.125λ 0 and 0.25λ 0 , where λ 0 corresponds to a wavelength associated with a center frequency of an operating band of the radiating element.
12 . The radiating element of claim 10 , wherein a capacitance between each of the coupling elements and a corresponding radiating arm is greater than 0.1 pF.

Description

FIELD The present invention relates to cellular communications systems and, more particularly, to radiating elements used in base station antenna systems. BACKGROUND Crossed dipole radiating elements can generate isotropic, omnidirectional, dual-polarized, and circularly polarized radiation; and, when combined into arrays of multiple radiating elements, may be suitable for single-band, multiband, and wideband wireless communication systems. These systems include, but are not limited to, broadcasting services, satellite communications, mobile communications, global navigation satellite systems, radio frequency (RF) identification, wireless power transmission, wireless local area networks, and other wireless communications. The basic design of a conventional cross dipole radiating element consists of a pair of two half-wavelength dipoles, which are aligned at right angles relative to each other and may be supplied with currents of equal magnitude that are in phase quadrature in some applications. In addition to wireless communications, many other applications similarly require antennas that radiate a unidirectional pattern with significant front-to-back ratio to ensure high security and efficiency in the propagation channels. Accordingly, such antennas typically utilize rear-side reflectors that support generation of the unidirectional pattern with dual polarization. With the rapid development of today's wireless communication markets, demands for improved antenna design have focused on: compact size, higher radiation efficiencies, broader bandwidths, multiple bands, specific radiation profiles with improved return loss (RL) and isolation (ISO), ease of fabrication and integration, and lower cost. SUMMARY A cross-polarized dipole radiating element according to an embodiment of the invention utilizes an embedded rear-facing loop to achieve compact size, excellent impedance matching, and improved roll-off, return loss and isolation. In some embodiments, the radiating element includes a substrate having a quad-arrangement of radiating arms on a forward-facing surface thereof, and a radio-frequency (RF) coupled loop on a rear-facing surface thereof, and a feed stalk electrically coupled to the quad-arrangement of radiating arms. A cross-polarized feed signal network may also be electrically coupled to a base of the feed stalk, and supported on an underlying reflector. In some of these embodiments, the RF coupled loop includes a quad-arrangement of rear-facing coupling elements, which extend opposite corresponding ones of the quad-arrangement of radiating arms, and a quad-arrangement of metal traces, which are configured to electrically couple the quad-arrangement of coupling elements together into a closed electrical loop. The centroids of the quad-arrangement of coupling elements may be located at four corners of a square, when viewed from a plan perspective; each of the coupling elements may also have a circular, polygonal or similar shape, when viewed from the plan perspective. In some further embodiments, the metal traces may have a linear, arcuate or similar shape, when viewed from the plan perspective. According to additional embodiments of the invention, a capacitance between each of the radiating arms and underlying coupling element is greater than 0.1 pF, whereas each of the metal traces has a length in a range between 0.125λ0 and 0.25λ0, where λ0 corresponds to a wavelength associated with a center frequency of an operating band of the radiating element. The substrate may also be polygonal-shaped, and the quad-arrangement of radiating arms may fully or only partially cover the forward-facing surface of the substrate. A ratio of an area of each radiating arm relative to an area of a corresponding coupling element may also be in a range from 6 to 24. According to further embodiments of the invention, a cross-polarized dipole radiating element is provided, which includes a substrate having a quad-arrangement of radiating arms on a forward-facing surface thereof, and a radio-frequency (RF) coupled loop on a rear-facing surface thereof. This RF coupled loop includes a quad-arrangement of circular or polygonal-shaped coupling elements that are electrically coupled together, and overlap centroids of their respective radiating arms when viewed from a plan perspective. A rearwardly-extending feed stalk is also provided, which is electrically coupled at one end to the quad-arrangement of radiating arms, and at its base to a cross-polarized feed signal network. In some embodiments, the centroids of the quad-arrangement of coupling elements are located at four corners of a square, when viewed from the plan perspective. The centroids of the coupling elements may also be aligned with corresponding centroids of the radiating arms when viewed from the plan perspective. A quad-arrangement of metal traces may also be provided, which are configured to electrically couple the quad-arrangement of coupling elements together