Four-port omnidirectional antenna

Abstract

A four-port omnidirectional antenna includes a dielectric resonator, a first substrate, and a second substrate. The first substrate includes two sets of feed lines for providing two transverse magnetic (TM) modes, one of which is a higher-order mode. The second substrate also includes two sets of feed lines for providing two transverse electric (TE) modes, one of which is a higher-order mode. The dielectric resonator, the first substrate, and the second substrate are stacked together to form a double-layer printed circuit board (PCB). The feed lines are configured to be mutually isolated, generating fields excited by the two TM modes and the two TE modes, thereby enabling independent operation among the four modes.

Description

Technical Field

[0001] This invention relates to omnidirectional antennas. In particular, this invention relates to a four-port omnidirectional antenna for exciting four omnidirectional modes. Background Technology

[0002] With the rapid development of modern communication technology, the demand for data transmission is increasing. Full-duplex antennas, because they can simultaneously receive and transmit data, thereby reducing the number of antennas in terminal devices, are becoming increasingly important in research.

[0003] Traditional full-duplex antennas often require integration with other structures. Couplers, coplanar waveguides, substrate-integrated waveguides, parasitic structures, and resonant structures are common in full-duplex antenna designs, which increases the size and complexity of the terminal system.

[0004] In recent years, some novel duplex antennas have been proposed for single-antenna elements that can achieve duplex functionality independently without the need for additional structures, but their structures are relatively complex. Furthermore, they cannot be applied to base station operating frequency bands where all modes exhibit omnidirectional radiation characteristics. Summary of the Invention

[0005] According to a first aspect of the present invention, a four-port omnidirectional antenna is provided, comprising: (i) a dielectric resonator;

[0006] (ii) A first substrate in contact with the dielectric resonator, comprising a first set of feed lines and a second set of feed lines; the first set of feed lines is adapted to provide a fundamental transverse magnetic (TM) mode in a lower frequency band, while the second set of feed lines is adapted to provide a higher-order TM mode in a higher frequency band; and (iii) a second substrate in contact with the first substrate, comprising a third set of feed lines and a fourth set of feed lines; the third set of feed lines is adapted to provide a fundamental transverse electric (TE) mode in a lower frequency band, while the fourth set of feed lines is adapted to provide a higher-order TE mode in a higher frequency band. The first, second, third, and fourth sets of feed lines are configured to be mutually isolated, thereby enabling the fundamental transverse magnetic mode, the higher-order transverse magnetic mode, the fundamental transverse electric mode, and the higher-order transverse electric mode to operate independently of each other.

[0007] Preferably, the antenna is a duplex antenna, suitable for simultaneously receiving and transmitting data in one frequency band or two different frequency bands, between any two modes of two TM modes and two TE modes.

[0008] In one specific implementation, the first set of feeder lines are electrically connected to and fed by a first power divider to form a first feeder network.

[0009] Preferably, the first power divider is radially arranged between the third and fourth sets of feed lines on the second substrate, and includes a circumferentially extending arcuate strip with a cascaded structure along the radial direction for providing first-stage power distribution and second-stage power distribution.

[0010] More preferably, the circumferentially extending arcuate strip includes a first arcuate strip for providing first-stage power distribution. The first arcuate strip has a circumferential span of 180 degrees.

[0011] In a variation of the preferred embodiment, the first set of feed lines includes four short stubs extending radially in the outer region of the second set of feed lines, with each short stub spaced 90 degrees apart.

[0012] In another variation of the preferred embodiment, a second set of feed lines is connected from the central via to the central patch to form a second feed network.

[0013] Preferably, the second set of feed lines includes four short-circuit stubs. These short-circuit stubs extend radially at the center of the first substrate, and are arranged orthogonally to each other, while simultaneously connecting to each other at the central patch.

[0014] In another variation of the preferred embodiment, the third set of feeder lines is electrically connected to and powered by the second power divider to form a third feeder network.

[0015] Preferably, the second power divider is disposed in the outermost region of the second substrate.

[0016] Alternatively or additionally, the third set of feeders includes a first ring consisting of four discrete angular strips in the outer region relative to the fourth set of feeders, wherein each discrete angular strip of the first ring has a first arc length defined by a first diagonal length.

[0017] In another variation of the preferred embodiment, the fourth set of feeder lines is electrically connected to and powered by the third power divider to form a fourth feeder network.

[0018] Preferably, the third power divider is located in the inner region of the second substrate.

[0019] Alternatively or additionally, the fourth set of feeders includes a second ring consisting of four discrete angled strips in the inner region relative to the third set of feeders, wherein each discrete angled strip of the second ring has a second arc length defined by the length of the second diagonal.

[0020] In another variation of the preferred embodiment, the antenna includes a grounded coplanar waveguide (GCPW) structure located around a third power divider on a second substrate to reduce cross-polarization.

[0021] In another variation of the preferred embodiment, the antenna further includes a filtering structure comprising an arc-shaped structure for eliminating coupling between the first set of feed lines and the second set of feed lines. The size of this arc-shaped structure is approximately equivalent to the half-wavelength of the frequency-dependent higher-order TM mode.

[0022] In another variation of the preferred embodiment, the first substrate and the second substrate are circular and planar, and are stacked along a common axis of rotation.

[0023] In another variation of the preferred embodiment, the dielectric resonator is cylindrical and made of a material with a dielectric constant of 5.

[0024] In another variation of the preferred embodiment, the two different frequency bands include a first frequency band of 1.8 GHz and a second frequency band of 3.9 GHz.

[0025] According to a second aspect of the invention, a four-port omnidirectional antenna is provided, having a dielectric resonator with a dielectric constant of 5 and a double-layer PCB. This single resonator can excite four omnidirectional DR (dielectric resonance) modes, two of which correspond to a set of orthogonal polarizations and are excited within a frequency band.

[0026] In one embodiment, any two modes can be selected for duplex applications, and they will hardly interfere with each other.

[0027] In one embodiment, the antenna is very compact and can be easily applied to base station communication systems.

[0028] A four-port omnidirectional antenna according to one embodiment of the present invention includes four sets of feed lines arranged on a double-stepped substrate to provide four omnidirectional modes. The position and structural design of the four sets of feed lines ensure high isolation between the four omnidirectional modes. This allows the four modes to operate with good in-band and inter-band isolation.

[0029] In particular, when operating as a duplex antenna, the high degree of isolation between the four modes allows any two modes to operate simultaneously, which is of great significance for simplifying duplex antenna systems. Attached Figure Description

[0030] Exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, wherein:

[0031] Figure 1A side view of a four-port omnidirectional antenna according to an embodiment of the present invention is shown.

[0032] Figure 2 It shows Figure 1 The top view of the first and second substrates of the four-port omnidirectional antenna shown.

[0033] Figure 3 This is a simulated reflection coefficient and in-band isolation curve of a four-port omnidirectional antenna operating in a lower frequency band according to an embodiment of the present invention.

[0034] Figure 4 This is a simulated reflection coefficient and in-band isolation curve of a four-port omnidirectional antenna according to an embodiment of the present invention when it operates in a higher frequency band;

[0035] Figure 5 This is a simulation result of the inter-band isolation of a four-port omnidirectional antenna operating in a lower frequency band according to an embodiment of the present invention.

[0036] Figure 6 This is a simulation result of the inter-band isolation of a four-port omnidirectional antenna operating in a higher frequency band according to an embodiment of the present invention.

[0037] Figure 7 This is a four-port omnidirectional antenna according to an embodiment of the present invention under different filter structure lengths TM 01δ Patterns and TM 02δ A graph showing the variation of isolation between modes with the length of the filter structure.

[0038] Figure 8a A four-port omnidirectional antenna according to an embodiment of the present invention is shown in TE 01δ+1 Radiation patterns on the yz and xy planes in the pattern.

[0039] Figure 8b A four-port omnidirectional antenna according to an embodiment of the present invention is shown in TM. 01δ Radiation patterns on the yz and xy planes in the pattern.

[0040] Figure 8c A four-port omnidirectional antenna according to an embodiment of the present invention is shown in TM. 02δ Radiation patterns on the yz and xy planes under the pattern.

[0041] Figure 8d A four-port omnidirectional antenna according to an embodiment of the present invention is shown in TE 03δ+1 Radiation patterns on the yz and xy planes in the pattern.

[0042] Before explaining any embodiments of the invention in detail, it should be understood that the application of the invention is not limited to the details and arrangement of components of the embodiments described below or shown in the drawings. The invention can be practiced or performed in various other ways. Furthermore, it should be understood that the wording and terminology used herein are for descriptive purposes only and should not be considered limiting. Detailed Implementation

[0043] Dielectric resonant antennas (DRAs) are easier to implement than other antenna types when three or more modes are required. DRAs, with their fixed size and materials, can achieve multi-mode (including multi-orthogonal mode) excitation under different feeding methods. Utilizing this characteristic, the same dielectric resonator can be excited through different ports, enabling the design of multi-band and multi-polarization antennas. Furthermore, DRAs offer advantages such as compact structure, low loss, flexible shape, and diverse feeding methods.

[0044] For effective application in base stations, signals need to be received and transmitted from all directions. One embodiment of this invention relates to a full-duplex four-port omnidirectional antenna that can cover the N3 and N77 operating frequency bands in the FR1 (frequency range 1) band and excite four omnidirectional modes through its four ports. The different modes can operate independently with isolation close to or greater than 20 dB. The antenna proposed in this embodiment is of significant importance for simplifying full-duplex systems.

[0045] One embodiment of a four-port omnidirectional dielectric resonant antenna is as follows: Figure 1 and Figure 2 As shown. See also Figure 1 The antenna 100 includes a printed cylinder serving as a dielectric resonator 110, and two substrates, namely a first substrate 120 and a second substrate 130. To achieve a wider bandwidth, the dielectric resonator 110 is made of a material with a dielectric constant of 5. Both substrates are made using ROGERSRO4003 printed circuit boards (PCBs) and are each 1.524 mm thick. The first substrate 120 (also serving as the upper substrate) is fixed to the lower surface of the dielectric resonator 110, while the second substrate 130 is fixed to the surface of the first substrate 120 as the lower substrate. The planar dimensions of the first substrate 120 are smaller than those of the second substrate 130.

[0046] The four ports 141, 142, 143, and 144 correspond to four sets of feed networks. The dielectric resonator 110 is excited through these four ports 141, 142, 143, and 144, generating two transverse magnetic (TM) modes and two transverse electric (TE) modes, respectively. The first TM mode (TM...) in the lower frequency band... 01δ The feed network of the second TM mode (TM mode) is fed from port 144, and the higher frequency band feeds from port 144. 02δThe feed network for the first TE mode (TE mode) is fed from port 142, in the lower frequency band. 01δ+1 The power supply network of the second TE mode (TE mode) is fed from port 141, which is a higher frequency band. 03δ+1 The power supply network (in this mode) is fed from port 143.

[0047] like Figure 2 As shown, the feed line for TM mode is arranged on the first substrate 120, while the feed line for TE mode and the first power divider 331 for the first TM mode are arranged on the second substrate 130.

[0048] TM and TE modes are very popular in Wi-Fi and base station applications because they both have omnidirectional radiation modes and the field directions are orthogonal to each other. It can be seen that the electric field of the TM mode is along the radial direction, corresponding to vertical polarization, while the electric field of the TE mode is along the φ direction, corresponding to horizontal polarization.

[0049] The first power divider 331 and the feed lines, placed on different substrates, are electrically connected via metallized vias. (For TM) 01δ The power divider 331 of the mode is disposed on the second substrate 130, located radially between the third and fourth groups of feed lines. A filter structure 340 is also included, which is located near the TM. 01δ The mode port is configured to eliminate coupling between the first and second set of feed lines. The arcuate portion of the filter structure 340 has dimensions similar to half the wavelength of the second TM mode frequency.

[0050] See Figure 2 Part (a) shows a top view of a first substrate 120, which is circular. It contains a first TM mode (TM) for a lower frequency band. 01δ The first set of feeder lines (in the mode) consists of four short wires 211, 212, 213, and 214. One side of the four short wires 211, 212, 213, and 214 is connected to the power divider 331 through a metal via, and the other side is shorted to ground 140, thereby forming the first feeder network.

[0051] In one embodiment, four stubs 211, 212, 213, and 214 have a rectangular shape and extend radially. They are located in the outer region of the first substrate 120, away from the center, reserving space for the second set of feed lines 220. The four stubs 211, 212, 213, and 214 are spaced 90 degrees apart from each other. The four stubs are of the same length.

[0052] A second set of feed lines is also disposed at the center of the first substrate 120 for providing a second TM mode (TM) at a higher frequency bandwidth. 02δ model).

[0053] The second set of feed lines consists of four short-circuit stubs 220, which are short-circuited to each other in an orthogonal manner, forming a cross shape. The four short-circuit stubs 220 are of the same size. The first and second sets of feed lines on the first substrate 120 are rotationally symmetrical, and the first substrate 120 and the second substrate 130 are stacked along a common rotation axis to form a double-layer PCB.

[0054] To avoid overlap between the second set of feed lines and the first set of feed lines, the angle between one of the short-circuited stubs in the second set of feed lines and one of the short-circuited stubs 211 in the first set of feed lines is 36 degrees. To form the second feed network, four short-circuited stubs 220 are connected to a circular metal patch and fed through a central metal via to excite TM at a frequency of 3.9 GHz. 02δ The design incorporates a central metal via and a circular patch that allows four shorted stubs to be fed with constant amplitude and phase. Grounded metal vias at the ends of the stubs improve impedance matching and reduce their size.

[0055] In order to excite the TM mode field in the dielectric resonator, the first and second sets of feed lines extend radially to excite a current similar to the dipole current.

[0056] It is worth noting that an arc-shaped structure is integrated in the first power divider 331, designed to reduce TM. 01δ With TM 02δ Coupling between modes. The size of the arc-shaped structure is comparable to half the wavelength of the higher-order mode frequency band, thus enabling it to function as a filter.

[0057] The four ports correspond to four sets of feed networks, three of which require uniform omnidirectional distribution via 1:4 power dividers 330, 331, and 332. To avoid feeder overlap, a double-layer substrate structure is used. All TE feed lines are located on the lower substrate, while all short-circuited stubs used to excite TM mode are placed on the upper substrate. To avoid overlap, TM... 01δ The power dividers 331 of the mode are distributed on the lower substrate and are connected by metallized vias.

[0058] Figure 2 Part (b) shows a top view of the second substrate 130, which includes a third set of feed lines and a fourth set of feed lines for providing two TE modes. The third set of feed lines includes a first ring consisting of four triangular strips 311, 312, 313, and 314, located in the outer region of the second substrate 130, away from the center, for use in the lower frequency band (TE). 01δ+1The first TE mode is provided in the mode. The four triangular strips in the first ring each have an arc length defined by the first diagonal α1. The four triangular strips 311, 312, 313, and 314 in the third group of feeders are spaced apart from each other and electrically connected through the second power divider 332 to form a third feeder network.

[0059] A fourth set of feed lines is provided in the inner region of the second substrate 130 to provide the second TE mode at a higher frequency band (TE03δ+1 mode). The fourth set of feed lines is electrically connected and powered through the third power divider 330, thereby forming a fourth feed network.

[0060] like Figure 2 As shown in (b), the fourth set of feed lines includes a second ring composed of four discrete angled strips 321, 322, 323, and 324. This second ring is located near the central region of the second substrate and does not overlap with the angled strips 311, 312, 313, and 314 of the third set of feed lines. Similarly, the four angled strips 321, 322, 323, and 324 of the fourth set of feed lines are spaced apart from each other, and their arc lengths are defined by the second diagonal α2. The arc lengths of the angled strips in the second ring are shorter than those in the first ring.

[0061] Using four arcs can suppress HEM compared to using two arcs. 21δ To excite the TE mode field in the dielectric resonator, a small current loop consisting of four corner bars is used to approximate the magnetic dipole, and these loops are powered by a 1-4 power divider.

[0062] In one embodiment, a second power divider 332 is disposed in the outermost region of the second substrate 130, while a third power divider 330 is disposed near the center of the second substrate 130. A grounded coplanar waveguide (GCPW) structure is also disposed around the third power divider 330 to reduce cross-polarization. Unwanted radiation and coupling caused by the power dividers can degrade the radiation mode.

[0063] Power dividers 330, 331, and 332 include circumferentially extending arcuate bars with a cascaded structure in the radial direction for providing first-stage power distribution and second-stage power distribution, wherein the circumferential span of the arcuate bar for providing first-stage power distribution is 180 degrees.

[0064] Based on the above feeding structure, horizontal and vertical polarization modes can be obtained. Their field distributions are naturally orthogonal to each other, thus achieving high isolation.

[0065] See Figure 3 and Figure 4 These two figures show the reflection coefficient and in-band isolation of each port in TM and TE modes.

[0066] Figure 3 This shows the reflection coefficient and in-band isolation in the low-frequency band. Labeled as S. 11 (Port 1) and S 44 Both curves for (port 4) are below -15dB at 1.85GHz, while the bandwidth below -10dB covers the range from 1.80GHz to 1.92GHz. The relative bandwidth is 6.5%. According to... Figure 3 As shown, S14 (ports 1 and 4) is below -30dB throughout the entire operating bandwidth, indicating good in-band isolation performance.

[0067] Figure 4 The reflection coefficient and in-band isolation for the high-frequency band are displayed. It can be seen that the two curves labeled S22 (port 2) and S33 (port 3) are both below -10dB in the 3.75GHz to 3.99GHz range and are well matched at 3.9GHz. The relative bandwidth is 6.3%. According to... Figure 4 As shown, S23 (ports 2 and 3) is below -15dB throughout the entire operating bandwidth and reaches -23dB at 3.75GHz.

[0068] Considering that different frequency bands operate simultaneously in a duplex system, interband coupling is also demonstrated.

[0069] Figure 5 and Figure 6 The working isolation of the ports in different frequency bands is shown. Figure 5 This shows the inter-band isolation in the low-frequency band. Figure 6 The inter-band isolation in the high-frequency band is shown. The results indicate that all ports maintain good isolation of close to or greater than 20 dB when operating simultaneously in the high-frequency and low-frequency bands.

[0070] Due to TM 01δ Pattern and TM 02δ The feed lines of the mode are close to each other and have parallel field distributions, resulting in severe coupling between them. To eliminate this coupling, in TM... 01δ A filter structure was loaded near the port of the mode. The effects of the shape and size of the filter structure on the isolation between the two modes were investigated.

[0071] Figure 7 This is a graph showing the effect of different arc dimensions of the filter structure on isolation. The graph shows that the isolation effect is the best when the small angle of the defined arc length is 43°, proving that higher-order modes are better filtered by the arc.

[0072] Figures 8a to 8dRadiation patterns of four omnidirectional modes of a dielectric resonant antenna according to an embodiment of the present invention are shown. The results demonstrate that the modes are symmetrical and undistorted with the same polarization, confirming that modes corresponding to different ports can operate simultaneously without interference, thus enabling the proposed DRA to achieve duplex functionality. The achieved gain reaches 1 dBi. It can be seen that the cross-polarization is below -15 dB at most angles in both the E and H planes.

[0073] As can be seen from the attached figure, the co-polarized radiation mode is approximately circular in the xy plane, with a non-uniformity within 2dB, indicating that uniform feeding and good omnidirectional radiation characteristics have been achieved.

[0074] The embodiment of the four-port omnidirectional antenna can operate simultaneously at 1.8 GHz and 3.9 GHz, corresponding to bandwidths of 6.5% and 6.3%, respectively. The four ports correspond to four modes: TM 01δ Pattern, TM 02δ Mode, TE 01δ+1 Pattern and TE 03δ+1 The mode exhibits good port matching, with the reflection coefficient of each port below -15 dB. Furthermore, each port can excite a symmetrical omnidirectional radiation pattern.

[0075] In duplex applications, any two TM modes and any two TE modes can operate simultaneously on two different frequency bands with a large frequency ratio.

[0076] like Figures 4 to 7 The simulation results show that the isolation between any two ports can be maintained above 15 dB across the entire operating frequency band. In some port combinations, the isolation can exceed 30 dB. Achieving such high isolation with a single antenna, without adding any couplers or parasitic structures, represents a significant technological breakthrough in the field of duplex systems, providing a highly practical and effective solution for real-world applications.

Claims

1. A four-port omnidirectional antenna, comprising: Dielectric resonator; A first substrate in contact with the dielectric resonator, the first substrate including a first set of feed lines and a second set of feed lines; The first set of feed lines is adapted to provide a basic transverse magnetic mode in a lower frequency band; The second set of feed lines is adapted to provide higher-order transverse magnetic modes in higher frequency bands; A second substrate in contact with the first substrate, the second substrate including a third set of feed lines and a fourth set of feed lines; The third set of feed lines is adapted to provide a basic transverse current mode in the lower frequency band. The fourth set of feed lines is adapted to provide a high-order transverse current mode in the higher frequency band. The first group of feed lines, the second group of feed lines, the third group of feed lines, and the fourth group of feed lines are configured to be mutually isolated, thereby enabling the basic transverse magnetic mode, the higher-order transverse magnetic mode, the basic transverse electric mode, and the higher-order transverse electric mode to operate independently of each other.

2. The four-port omnidirectional antenna according to claim 1, wherein the four-port omnidirectional antenna is a duplex antenna, adapted to simultaneously receive and transmit data in one frequency band or two different frequency bands, between any two of the basic transverse magnetic mode, the higher-order transverse magnetic mode, the basic transverse electric mode, and the higher-order transverse electric mode.

3. The four-port omnidirectional antenna of claim 1, wherein the first set of feed lines is electrically connected to and fed by a first power divider to form a first feed network.

4. The four-port omnidirectional antenna of claim 3, wherein the first power divider is radially arranged between the third set of feed lines and the fourth set of feed lines on the second substrate, and includes a circumferentially extending arcuate strip having a cascaded structure along the radial direction for providing first-stage power distribution and second-stage power distribution.

5. The four-port omnidirectional antenna of claim 4, wherein the circumferentially extending arcuate strip includes a first arcuate strip for providing the first-stage power distribution; the circumferential span of the first arcuate strip is 180 degrees.

6. The four-port omnidirectional antenna of claim 3, wherein the first set of feed lines comprises four stubs extending radially in the outer region of the second set of feed lines, and each of the stubs is spaced 90 degrees apart.

7. The four-port omnidirectional antenna according to claim 1, wherein the second set of feed lines is connected to the central patch from the central via to form a second feed network.

8. The four-port omnidirectional antenna of claim 7, wherein the second set of feed lines comprises four short-circuit stubs extending radially at the center of the first substrate; wherein the four short-circuit stubs are arranged orthogonally to each other and are simultaneously connected to each other at the central patch.

9. The four-port omnidirectional antenna of claim 1, wherein the third set of feed lines is electrically connected to and powered by the second power divider to form the third feed network.

10. The four-port omnidirectional antenna of claim 9, wherein the second power divider is disposed in the outermost region of the second substrate.

11. The four-port omnidirectional antenna of claim 9, wherein the third set of feed lines includes a first loop consisting of four discrete angled strips in an outer region relative to the fourth set of feed lines, wherein each discrete angled strip of the first loop has a first arc length defined by a first diagonal length.

12. The four-port omnidirectional antenna of claim 1, wherein the fourth set of feed lines is electrically connected to and powered by the third power divider to form a fourth feed network.

13. The four-port omnidirectional antenna of claim 12, wherein the third power divider is located in the innermost region of the second substrate.

14. The four-port omnidirectional antenna of claim 12, wherein the fourth set of feed lines includes a second loop consisting of four discrete angle strips in an inner region relative to the third set of feed lines, wherein each of the discrete angle strips of the second loop has a second arc length defined by a second diagonal length.

15. The four-port omnidirectional antenna of claim 12 further includes a grounded coplanar waveguide structure located around the third power divider on the second substrate to reduce cross-polarization.

16. The four-port omnidirectional antenna according to claim 5 further includes a filtering structure; the filtering structure includes an arc-shaped structure for eliminating coupling between the first set of feed lines and the second set of feed lines, wherein, The size of the arc-shaped structure is equivalent to half the wavelength of the frequency corresponding to the higher-order transverse magnetic mode.

17. The four-port omnidirectional antenna of claim 1, wherein the first substrate and the second substrate are circular and planar, and are stacked along a common axis of rotation.

18. The four-port omnidirectional antenna of claim 1, wherein the dielectric resonator is cylindrical and made of a material with a dielectric constant of 5.

19. The four-port omnidirectional antenna according to claim 2, wherein the two frequency bands include a first frequency band of 1.8 GHz and a second frequency band of 3.9 GHz.

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