Metal patch loaded miniaturized dielectric resonator antenna for base station

Abstract

The invention provides a metal patch loaded miniaturized dielectric resonator antenna for a base station, and relates to the technical field of wireless communication, a specific parasitic metal patch is introduced at the bottom of a dielectric resonator, the limitation that the traditional design only depends on geometric dimension to adjust the frequency is broken through, the TM12 high-order mode frequency is obviously pulled down to be close to a fundamental mode TM10 and fusion is realized, and the antenna has the advantages of being simple in structure and convenient to use. On the premise that the size of the antenna is not increased, the working bandwidth is expanded to 3.4-4.0 GHz. Through the structural design, a cross-shaped groove structure is loaded in the central area of the dielectric resonator, a current path of a TM20 parasitic mode is cut off accurately, directional diagram distortion and cross polarization interference caused by the mode are effectively suppressed, and it is ensured that the antenna has stable radiation performance. Therefore, the antenna has excellent broadband and radiation characteristics, can still keep compact physical size, low profile structure and simple processing technology, and meets the urgent demand of a microwave frequency band wireless communication terminal on high performance and miniaturization antennas.

Description

Technical Field

[0001] This invention relates to the field of wireless communication technology, specifically to a miniaturized dielectric resonator antenna with metal patch loading for a base station. Background Technology

[0002] With the rapid development of 5G and future 6G mobile communication, antenna resources are becoming increasingly scarce, and microwave antenna design faces the dual challenge of miniaturization and high performance. Dielectric resonator antennas (DRAs), due to their low-loss constituent materials and virtually no conductor loss compared to traditional microstrip patch antennas, offer significant advantages such as high radiation efficiency, high gain, and ease of integration, thus finding widespread application in communication systems. To adapt to the increasingly compact structure of modern communication equipment, antenna miniaturization is crucial. A common method for DRA miniaturization is to use dielectric materials with high dielectric constants; however, according to resonator Q-factor theory, a high dielectric constant leads to an increase in the antenna's Q-factor, significantly reducing its impedance bandwidth. To balance broadband performance and miniaturization, utilizing the multimode resonance principle of dielectric resonators to extend bandwidth has become the mainstream technical approach. This involves exciting multiple adjacent resonant modes within the dielectric resonator, causing their frequencies to approach and merge. While the theory is relatively mature, significant technical bottlenecks remain in the practical engineering design for flexibly controlling the mode frequencies.

[0003] Most existing multimode DRA designs rely on changing the aspect ratio of the dielectric block to adjust the frequency. This dependence on geometry means that the frequencies of each mode often change together, making independent control difficult. Broadbanding in current designs typically involves raising the resonant frequency of the fundamental mode to approach higher-order modes. However, this method is limited by the physical dimensions of the dielectric block, making further miniaturization of the antenna challenging. Furthermore, the process of exciting multiple modes to extend bandwidth often generates interfering parasitic modes, degrading the radiation performance of the dielectric resonator. Existing suppression techniques often employ metallized vias, metal walls, or complex 3D filter structures within the dielectric, significantly increasing fabrication difficulty and manufacturing costs, and potentially reducing antenna efficiency due to additional conductor losses. Summary of the Invention

[0004] Therefore, this invention provides a miniaturized dielectric resonator antenna with metal patch loading for base stations to address the combined technical problems of limited bandwidth, difficulty in flexibly adjusting higher-order mode frequencies, and deterioration of radiation characteristics by parasitic modes in existing dielectric resonator antennas used in base station applications, all of which are encountered in the pursuit of miniaturization. The miniaturized dielectric resonator antenna based on metal patch loading provided by this invention breaks through the limitations of traditional designs that rely solely on geometric adjustments to adjust the frequency by introducing a specific parasitic metal patch at the bottom of the dielectric resonator. This significantly pulls down the TM12 higher-order mode frequency to near the fundamental mode TM10 and achieves fusion, thereby effectively extending the operating bandwidth to 3.4-4.0 GHz without increasing the antenna size. Simultaneously, this invention focuses on loading a cross-shaped slot structure in the central region of the dielectric resonator through structural design, precisely cutting off the current path of the TM20 parasitic mode, thereby effectively suppressing the pattern distortion and cross-polarization interference caused by this mode, ensuring stable radiation performance of the antenna throughout the entire operating frequency band. The ultimate goal is to enable the antenna to maintain a compact physical size, low profile structure, and simple manufacturing process while possessing excellent broadband and radiation characteristics, thereby meeting the urgent need for high-performance, miniaturized antennas in microwave band wireless communication terminals.

[0005] The present invention provides a miniaturized dielectric resonator antenna based on a metal patch loading. The antenna structure, from bottom to top, includes: a pair of differential feed networks, a second dielectric substrate, a metal ground plane, a first dielectric substrate, a parasitic metal patch layer, and a dielectric resonator with a cross-shaped slot. Specifically: the differential feed networks are printed below the first substrate; the metal ground plane covers the upper surface of the second dielectric substrate and the lower surface of the first dielectric substrate; the parasitic metal patch is printed on the upper surface of the first dielectric substrate; and the dielectric resonator is tightly fitted onto the parasitic metal patch.

[0006] Furthermore, the parasitic metal patch is located directly below the dielectric resonator, with its geometric center coinciding with the center of the dielectric resonator. This metal patch does not directly radiate energy outwards as a radiator, but rather acts as an electromagnetic loading element. The parasitic metal patch is designed as four small square patches, with gaps in the middle to accommodate differential feed probes. Its physical dimensions are precisely designed to adjust the electromagnetic field boundary conditions fed into the dielectric resonator. Specifically, this patch introduces an additional capacitance effect at the bottom of the dielectric resonator. This loading effect significantly alters the electric field distribution of the higher-order mode (TM12), thereby lowering the resonant frequency of the TM12 mode and bringing it closer to the fundamental mode (TM10), thus utilizing the dual-mode fusion characteristic to extend the bandwidth.

[0007] Furthermore, the dielectric resonator is made of a ceramic material with a dielectric constant of 16, and its geometric center region has a semi-through cross-shaped air slot. This cross-shaped slot is a defect structure formed by removing the dielectric material. Its working mechanism is as follows: In a rectangular dielectric resonator, the electric field distribution of the parasitic mode TM20 is usually concentrated in the central region. The cross-shaped slot disrupts the dielectric continuity of the TM20 mode, cuts off its equivalent current path, and thus suppresses the TM20 mode with almost no impact on the TM10 and TM12 modes, eliminating the antenna performance degradation caused by it.

[0008] Furthermore, the antenna employs a pair of differential feed networks and two pairs of metal probes for differential feeding and dual polarization. The metal probes pass through the metal ground plane and the first and second dielectric substrates, directly inserting into the dielectric resonator. The differential feed networks provide excitation signals with equal amplitude and 180-degree phase difference, which can effectively excite the desired modes (TM10 and TM12) on the one hand, and naturally improve port isolation and cross-polarization by utilizing the symmetry of the differential signals on the other hand.

[0009] The key innovation of this invention lies in enabling higher-order modes to operate at the fundamental mode frequency without changing the size of the dielectric block. It specifically utilizes the characteristics of the TM20 mode's field strength distribution at the center, suppressing the mode by physically cutting off its path, thus solving the problem of performance degradation in multimode antennas. Simultaneously, differential feeding is employed. The combination of these three elements achieves comprehensive performance in terms of broadband, miniaturization, and high radiation purity, covering the mainstream 5G microwave frequency band of 3.4-4.0 GHz. This structure creatively utilizes a parasitic patch located at the interface between the dielectric resonator and the dielectric substrate to introduce a capacitive load, pulling the higher-order mode (TM12) frequency down to near the fundamental mode (TM10). A cross-shaped groove is etched on the dielectric resonator to suppress the interfering higher-order mode (TM20), thereby enabling higher-order modes to operate at the fundamental mode frequency and achieving broadband coverage of 3.4-4.0 GHz on a compact single dielectric block.

[0010] The present invention has the following advantages over the prior art:

[0011] 1. This invention's antenna cleverly utilizes a metal patch at the bottom of the dielectric resonator, leveraging the capacitive loading effect it introduces to significantly pull the higher-order mode (TM12) frequency down from the high-frequency band to near the fundamental mode (TM10). This mechanism allows the antenna to overcome the limitations of miniaturization and wide bandwidth without increasing the physical size of the dielectric block, achieving continuous broadband coverage of 3.4-4.0 GHz (relative bandwidth 16.2%), perfectly covering the critical microwave frequency band Sub-6 GHz. Compared to traditional single-mode dielectric resonator antennas in the same frequency band, this invention significantly reduces size while maintaining the same bandwidth performance.

[0012] 2. This invention, by creating a cross-shaped air slot in the central region of the dielectric resonator, physically cuts off the current path of the interference mode. Combined with differential feeding technology, the antenna maintains stable wide-side radiation characteristics throughout the entire operating passband without performance degradation or pattern distortion. Simulation results show that the antenna's cross-polarization level in the main radiation direction is better than -23 dB, ensuring polarization purity.

[0013] 3. Compared with existing technologies that employ complex structures involving multi-layer dielectric stacking, internal perforation, or side loading, this invention utilizes a single dielectric block combined with a bottom-plane printed patch structure. The parasitic patch is directly printed on the dielectric substrate, eliminating the need for additional three-dimensional support components and effectively reducing the antenna's profile height. The cross-slot fabrication process is simple and easy for mass production. Benefiting from the low-loss characteristics of the dielectric resonator itself and the effective utilization of higher-order modes, this invention maintains high gain and good stability within the 3.4-4.0 GHz operating frequency band. Simulation data shows that the antenna's average gain reaches 7.3 dBi, and the gain is relatively stable, making it suitable for microwave communication systems with high signal coverage quality requirements. Attached Figure Description

[0014] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0015] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0016] Figure 2 This is a top view of the present invention.

[0017] Figure 3 This is a bottom view of the present invention.

[0018] Figure 4 This is an exploded view of the structure of the present invention.

[0019] Figure 5 This is a diagram showing the reflection coefficient, isolation, and gain results of the present invention.

[0020] Figure 6 This invention relates to antenna array radiation patterns at 3.48 GHz and 3.98 GHz.

[0021] Explanation of reference numerals in the attached figures:

[0022] 1. Dielectric resonator; 11. Cross-shaped groove; 121. Probe via; 211. Parasitic metal patch; 221. Feed probe; 3. First dielectric substrate; 31. First via; 4. Metal reflective ground plane; 41. Clearing hole; 5. Second dielectric substrate; 51. Second via; 61. First differential feed network; 62. Second differential feed network. Detailed Implementation

[0023] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Example 1

[0025] This embodiment provides a miniaturized dielectric resonator antenna with a metal patch for use in a base station. Figure 1 The figure shows a schematic diagram of the overall structure of the miniaturized dielectric resonator antenna based on metal patch loading provided in this embodiment. As shown in the figure, the antenna adopts a vertical stacked structure, and its main body from top to bottom mainly includes: dielectric resonator 1, parasitic metal patch 211, first dielectric substrate 3, metal reflective ground plane 4, second dielectric substrate 5, and the feed network located at the bottom layer.

[0026] Figure 2 The image shows a top view of the antenna, clearly revealing the structural details of the top-layer dielectric resonator 1. Dielectric resonator 1 is made of ceramic material with a dielectric constant of 16, and has a semi-through cross-shaped slot 11 at its geometric center. This cross-shaped slot 11 is an air groove formed by removing a portion of the dielectric material; its core function is to cut off the current path of the TM20 parasitic mode inside the dielectric resonator, thereby suppressing the excitation of this higher-order mode and optimizing radiation performance. Four probe through-holes 121 are also provided inside the dielectric resonator 1 to accommodate metal feed probes. Figure 3The bottom-layer feeding structure is shown. Both the first dielectric substrate 3 and the second dielectric substrate 5 are made of plates with a dielectric constant of 2.2 and thicknesses of 1.57 mm and 0.78 mm, respectively. A metal reflective ground plane 4 is sandwiched between them as the antenna's reference ground. There are no signal traces, but large-diameter probe clearance holes 41 are provided at the corresponding probe positions to prevent short circuits. The first differential feed network 61 and the second differential feed network 62 are printed on the lower surface of the second dielectric substrate 5. Both the first differential feed network 61 and the second differential feed network 62 include a signal input microstrip line, a T-junction connected to the signal input microstrip line, and two transmission line branches of unequal length extending from the T-junction. The physical length difference between the two transmission line branches is configured to correspond to half a waveguide wavelength of the operating center frequency to generate a 180-degree phase difference at the ends of the two branches. The ends of the two transmission line branches are electrically connected to the corresponding feed probes 221 to provide differential excitation signals with equal amplitude and a 180-degree phase difference to the dielectric resonator 1. Figure 3 As shown, the input microstrip line of the feed network is located near the edge of the second dielectric substrate 5, extending inward to connect to a T-junction. Each T-junction has two transmission line branches of unequal path lengths extending inward, and the ends of the two transmission line branches are electrically connected to the corresponding feed probe 221. These two feed networks have identical structures and are orthogonal to each other, and are used to excite two orthogonal linearly polarized waves respectively. Figure 4 The exploded view of the antenna structure shows four discrete parasitic metal patches 211 printed directly below the dielectric resonator 1 and on the upper surface of the first dielectric substrate 3. These four patches are arranged symmetrically in a 2×2 matrix, corresponding to the four regions at the bottom of the dielectric resonator 1. These parasitic metal patches 211 are not directly connected to the signal source, but rather serve as capacitive load elements. The design principle is to use the metal patches to change the electromagnetic boundary conditions at the bottom of the dielectric resonator, significantly pulling the resonant frequency of the higher-order mode (TM12) down to near the fundamental mode (TM10), thereby expanding the operating bandwidth without increasing the antenna size. Specifically, taking the first differential feed network 61 as an example, when a signal is input, it is split into two paths by a T-type power divider network, generating differential excitation signals with equal amplitude and a 180-degree phase difference. These two signals are respectively connected to two feed probes 221. Figure 4 As shown, four feed probes 221 extend vertically upwards, passing sequentially through the second through-hole 51 on the second dielectric substrate 5, the clearance hole 41 on the metal reflective ground plate 4, and the first through-hole 31 on the first dielectric substrate 3, finally inserting into the probe through-hole 121 of the dielectric resonator 1. This differential probe feeding method, combined with the cross-shaped groove 11 in the center of the dielectric, can further improve the isolation between ports and reduce the cross-polarization level.

[0027] Figure 5This figure shows the simulation results of the antenna's reflection coefficient, isolation, and gain in this embodiment. The gray shaded area in the figure represents the target operating frequency band of the antenna (3.4-4.0 GHz). Within this frequency band, the port reflection coefficients S11 and S22 are both below -15 dB, indicating that the antenna has good impedance matching characteristics. Meanwhile, the isolation S21 between the two ports remains below -40 dB throughout the entire frequency band, indicating that the first differential feed network 61 and the second differential feed network 62 do not interfere with each other. The average gain of the antenna within the operating frequency band is approximately 7.3 dBi.

[0028] Figure 6 The normalized radiation patterns of the antenna at two typical frequency points, 3.48 GHz and 3.98 GHz, are shown. The antenna maintains stable wide-side radiation characteristics throughout the entire operating bandwidth, and the cross-polarization is below -25 dB, achieving high-purity radiation performance.

[0029] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A metal patch loaded miniaturized dielectric resonator antenna for a base station, characterized by, The application relates to a dielectric resonator antenna. The dielectric resonator (1) is internally provided with a half-penetrating cross-shaped slot (11) from bottom to top, wherein the cross-shaped slot (11) is an air slot formed by digging part of dielectric material.

2. The metal patch loaded miniaturized dielectric resonator antenna for base stations of claim 1, wherein, The dielectric resonator (1) is internally provided with four probe through holes (121) for accommodating metal feeding probes (221).

3. The metal patch loaded miniaturized dielectric resonator antenna for base stations of claim 2, wherein, The parasitic metal patch (211) is provided with four groups and is arranged in a 2*2 matrix symmetry.

4. The metal patch loaded miniaturized dielectric resonator antenna for base stations of claim 3, wherein, The first dielectric substrate (3) is provided with a first through hole (31).

5. The metal patch loaded miniaturized dielectric resonator antenna for base stations of claim 4, wherein, The metal reflecting floor (4) is provided with a void hole (41).

6. The metal patch loaded miniaturized dielectric resonator antenna for base stations of claim 5, wherein, The second dielectric substrate (5) is provided with a second through hole (51).

7. The metal patch loaded miniaturized dielectric resonator antenna for base stations of claim 6, wherein, The feeding network comprises a first differential feeding network (61) and a second differential feeding network (62) printed on the lower surface of the second dielectric substrate (5).

8. The metal patch loaded miniaturized dielectric resonator antenna for base stations of claim 7, wherein, The first differential feeding network (61) and the second differential feeding network (62) are both printed on the lower surface of the second dielectric substrate (5) and are orthogonally distributed in space, and both the first differential feeding network (61) and the second differential feeding network (62) comprise a signal input microstrip line, a T-shaped junction connected with the signal input microstrip line and two transmission line branches with different lengths extended from the T-shaped junction, wherein the physical length difference of the two transmission line branches is configured to correspond to half of the guided wave wavelength of the working center frequency to generate a phase difference of 180 degrees at the ends of the two branches, and the ends of the two transmission line branches are respectively electrically connected with corresponding feeding probes (221) for providing the dielectric resonator (1) with differential excitation signals with equal amplitude and a phase difference of 180 degrees.

9. The metal patch loaded miniaturized dielectric resonator antenna for base stations of claim 8, wherein, The four feeding probes (221) vertically extend upwards, sequentially pass through the second through hole (51) on the second dielectric substrate (5), the void hole (41) on the metal reflecting floor (4), the first through hole (31) on the first dielectric substrate (3) and finally are inserted into the probe through hole (121) of the dielectric resonator (1).

10. The metal patch loaded miniaturized dielectric resonator antenna for base stations of claim 9, wherein, ​

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