Ultra compact ultra broad band dual polarized base station antenna

Abstract

The invention refers to a radiating element comprising a support structure, a first dipole arranged on the support structure, and at least one electrically closed ring arranged on the support structure, wherein the ring surrounds the first dipole and is galvanically isolated from the first dipole, wherein a resonance frequency of the first dipole is higher than a center frequency of an operational bandwidth of the radiating element.

Claims

1. A radiating element, comprising: a support structure having a first horizontal layer and a second horizontal layer; a first dipole and a second dipole arranged on the first horizontal layer, the first dipole is placed in a +45 degree polarization direction, and the second dipole is placed in a −45 degree polarization direction; and a first electrically closed ring arranged on the first horizontal layer or the second horizontal layer, wherein the first electrically closed ring surrounds the first dipole and the second dipole from a top or bottom view, and is galvanically isolated from the first dipole and the second dipole, wherein the first electrically closed ring is floating, wherein the first electrically closed ring has a form of a square, and wherein a first planar dipole arm of the first dipole has a groove on an outer corner of the first planar dipole arm.

2. The radiating element of claim 1, wherein a resonance frequency of the first dipole is higher than a center frequency of an operational bandwidth of the radiating element.

3. The radiating element of claim 1, wherein a resonance frequency of the first dipole is higher than an upper limit of an operational bandwidth of the radiating element.

4. The radiating element of claim 1, wherein a vertical distance between the first horizontal layer and the second horizontal layer is less than 5% of an electrical length of the first dipole.

5. The radiating element of claim 1, further comprising a second electrically closed ring arranged on the support structure, wherein the second electrically closed ring surrounds the first dipole and the second dipole, and is galvanically isolated from the first dipole and the second dipole.

6. The radiating element of claim 5, wherein the second electrically closed ring is arranged in a third horizontal layer of the support structure having a vertical distance to the first horizontal layer, in which the first dipole and the second dipole are arranged, not more than 5% of a total length of the first dipole.

7. The radiating element of claim 5, wherein the support structure is a printed circuit board (PCB), and wherein the first electrically closed ring is formed on a top side of the PCB and the second electrically closed ring is formed on a bottom side of the PCB.

8. The radiating element of claim 1, wherein the radiating element is configured to be mounted on a reflector and further comprises: a further support structure configured to elevate the support structure over the reflector, when the radiating element is mounted on the reflector.

9. The radiating element according to claim 8, wherein the further support structure comprises a first pair of dipole feet, and wherein the first pair of dipole feet has at least 4 electrical or capacitive connecting points to the first dipole.

10. The radiating element of claim 1, wherein edges of the square are cut into a diagonal.

11. The radiating element of claim 10, further comprising for the first dipole a first pair of dipole feet and for the second dipole a second pair of dipole feet, which are arranged perpendicular to each other, wherein the first and second pairs of dipole feet, respectively, are formed by a first and second printed circuit boards (PCBs) that are stuck together.

12. The radiating element of claim 11, wherein at least one of the first or the second pair of dipole feet are galvanically or capacitively connected with at least one of the first dipole or the second dipole.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) To illustrate the technical features of embodiments of the present invention more clearly, the accompanying drawings provided for describing the embodiments are introduced briefly in the following. The accompanying drawings in the following description are merely some embodiments of the present invention, but modifications on these embodiments are possible without departing from the scope of the present invention as defined in the claims.

(2) FIG. 1 shows a perspective view of a radiating element.

(3) FIG. 2 shows a top view of the radiating element of FIG. 1.

(4) FIG. 3 shows a bottom view of the radiating element of FIG. 1.

(5) FIG. 4 shows a perspective view of a radiating element of FIG. 1 from the bottom side.

(6) FIG. 5 shows a perspective side view of only the dipole feet of the radiating element of FIG. 1.

(7) FIG. 6 shows a perspective view of a radiating element of FIG. 1 mount on a supporting structure.

(8) FIG. 7 shows a perspective view of the radiating element of FIG. 1 indicating electrical polarisations of the first and second dipoles.

(9) FIG. 8 shows a top view of a further radiating element.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(10) With reference to FIGS. 1 to 3 an embodiment of a radiating element is described. The radiating element includes a support structure 2 in the form of a quadratic PCB. On the top surface of the PCB 2 first and second dipoles 4 and 6 are located on a single layer. The first dipole 4 includes two opposing dipole arms 4a, 4b. The second dipole 6 includes two opposing dipole arms 6a, 6b. Just for illustration purposes, the PCB 2 is illustrated as transparent. The dipoles 4 and 6 are arranged perpendicular to each other. With reference to FIG. 7, an example of an electric polarisation of the dipole elements is indicated by arrows 8 and 10. A skilled person will understand that the dipoles can include any phase shift such that any linear or circular or elliptical polarized radiation field can be radiated from the radiating element.

(11) The top surface of the PCB 2 also includes a ring 12 which in the present embodiment has the form of a square wherein the edges of the square are cut into a diagonal. The top ring 12 surrounds the first and second dipole 4 and 6 completely. Moreover, the top ring 12 is galvanically separated from the dipoles 4 and 6 as well as from all other electrical parts of the radiating element. Hence the top ring 12 is floating.

(12) On the bottom surface of the PCB 2, as shown in FIG. 3, a second electrical ring 14 is located which also surrounds the first and second dipoles 4 and 6. The second ring 14 is also galvanically separated from ground and from any other electrical parts of the antenna element. It should be noted that the dipoles 4 and 6 as shown in FIG. 3 (which can be seen due to the transparent illustration of the PCB 2) are the same as the ones shown in FIG. 1 the dipoles 4 and 6 are only arranged on one side (in this case the top side) or layer of the PCB. However, the diploes 4 and 6 could also be arranged on another layer or even on different layers of the PCB.

(13) The vertical distance of the first ring 12 and the second ring 14 is only defined by the thickness of the PCB 2. In general, the vertical distance between the first and second ring 12 and 14 as well as the vertical distance with respect to the layer of the first and second dipoles 4 and 6 is very small (less than 5% or 2%) in comparison to the length of each of the dipoles 4 or 6 in their horizontal extension.

(14) Furthermore, it can be seen that neither the first ring 12 nor the second ring 14 overlap with the dipoles 4 and 6, when seen from the top or bottom view.

(15) The construction of the ring structure surrounding the dipole structure maintains an ultra broad band characteristic of an antenna while reducing the radiation surface compared to radiating elements without such an additional ring structure. By this means, the dipoles manage to shift the frequency since the dipoles resonate out of the useful band of the LB and the HB is electrical invisible to the LB or vice versa. The top and bottom rings 12 and 14 provide an additional resonating structure to the dipole elements, hence, increasing the operating frequency of the radiating element. The rings 12 and 14 remain invisible to the LB array as they are not directly connected to ground. A further advantage is that the rings are integrated on the same carrier structure, namely the PCB 2, such that no additional part are required to mechanically connect the rings 12, 14 on the radiating element.

(16) With reference to FIGS. 3 to 5 a foot structure of the radiating element is described. Each of the dipoles 4 and 6 is connected with a pair of dipole feet 24 and 26. The pairs of dipole feet 24 and 26 each include a single PCB which are stacked together as shown in FIG. 5. On the front end of the PCBs of the dipole feet 24 and 26, respectively, each PCB includes four connecting points in form of four soldering tags 40a, 40b, 40c, 40d which are inserted in respective slots in the first and second dipole 4, 6 as shown in the top view of FIG. 2. Thus, each dipole foot is connected by two connecting points to the respective dipole arm. As shown in FIGS. 3 and 4, the soldering tags of the dipole feet are directly galvanically connected to the respective dipole. FIG. 8 shows another top view on radiating element according to an embodiment of the present invention. Also this radiating element comprises two cross polarized dipoles 4 and 6 and a floating top ring 12 surrounding the two dipoles 4, 6. The dipoles 4, 6 and the top ring are arranged on the same PCB layer as the top ring 12. Furthermore, a solder stop 34 is shown in Figure used to avoid solder material for the soldering tags spill over the PCB. However, the metal material of the dipoles 4 and 6 is continuous below the solder stop 34.

(17) Each dipole feet 24 and 26 shown in FIGS. 4 and 5 includes a PCB which is planar conductive on one side 28 and include a general U-shaped conductive path 30 on the opposing side. The planar conductive side 28 which is also galvanically connected to the mentioned soldering tags of each dipole feet 24, 26 will typically be connected to ground. The conductive path 30 of each of the dipole feet 24, 26 will typically be connected to be connected to an RF signal source.

(18) With reference to FIG. 6, the radiating element is shown mounted on a surface structure 32 which may include also a PCB (e.g. for mounting on a reflector board). As can be seen from FIG. 6, the pairs of dipole feet 24 and 26 provide for a defined distance between the supporting structure 2 and a reflector board. Thus, the radiating element can be easily installed in an antenna structure. It should be understood that multiple of the radiating elements can be installed on a reflector next to each other in a single base station antenna structure.

(19) It is implicit that all the previous descriptions are still valid for a single polarized radiating element, which would include a single dipole instead of two; indeed the principle behind the electromagnetic coupling between ring and dipole remains valid. Hence, further embodiments of the present invention provide radiating elements with only one dipole or even with more than two dipoles.

(20) The foregoing descriptions are only implementation manners of the present invention and the protection of the scope of the present invention is not limited to this. Any variations or replacements can be easily made through person skilled in the art. Therefore, the protection scope of the present invention should be subject to the protection scope of the attached claims.