A bidirectional radiating planar dipole antenna array operating in the millimeter wave frequency band

Abstract

The present invention discloses a bidirectional radiating planar dipole antenna array operating in the millimeter wave frequency band, comprising a first metal sheet, a first dielectric substrate, a second dielectric substrate, a second metal sheet, a third dielectric substrate, and a third metal sheet; the first metal sheet is attached to the upper surface of the first dielectric substrate; the second dielectric substrate is attached to the lower surface of the first dielectric substrate; the third dielectric substrate is located below the second dielectric substrate; the upper and lower sides of the second metal sheet are attached to the lower surface of the second dielectric substrate and the upper surface of the third dielectric substrate respectively, and the third metal sheet is attached to the lower surface of the third dielectric substrate. The present invention realizes bidirectional radiation characteristics within the operating frequency band, and simultaneously realizes high gain and low profile characteristics. The antenna array consists of two dipole antenna units with the same structure and a power divider.

Description

Technical Field

[0001] The present invention belongs to the field of antenna technology, and in particular relates to a bidirectional radiation planar dipole antenna array operating in a millimeter wave frequency band. Background Art

[0002] The rapid development of the fifth generation mobile communication technology (5G) has made millimeter wave antenna technology a hot research and development topic in the world today. It has also posed new challenges to the breadth of 5G mobile communication coverage and the low-cost improvement of communication capacity. Especially for some specific use occasions where the electromagnetic field is distributed in a narrow and long space, such as tunnels, indoor corridors, and narrow streets, the antenna is required to have not only a sufficiently wide working frequency band, high gain, and fast transmission rate in terms of working characteristics, but also miniaturization and easy integration in structure. Therefore, the research and design of high-performance millimeter wave antennas with bidirectional radiation characteristics is of great significance to the development of 5G communication systems.

[0003] At present, there are many antenna structures that can achieve this bidirectional radiation characteristic, such as: bidirectional stacked microstrip dipole antenna with multi-layer disk array structure (MDAS), by placing two identical MDAS structures back to back on both sides of a dipole exciter, finally a highly symmetrical radiation pattern is obtained; 6 folded dipoles are collinearly arrayed and fed at the center of the array to ensure the symmetry of the antenna array, and finally a bidirectional end-fire mode with high gain and low cross-polarization level is achieved; the ultra-low profile Huygens dipole antenna with different working modes is controlled by diode switches. When both diodes are turned on, the two magnetic dipoles are excited in phase, and the electric dipole is also excited in phase, so that the antenna achieves bidirectional radiation. However, these types of bidirectional antennas are usually large in size and have complex feeding structures, which are not suitable for the integrated development of modern communication equipment. In addition, the existing bidirectional radiating antennas mostly work in low frequency bands, and there are few reports on millimeter-wave bidirectional radiating antennas with high gain, low profile and wide working frequency band. Summary of the invention

[0004] In view of the defects in the above-mentioned prior art, the present invention provides a bidirectional radiation planar dipole antenna array operating in the millimeter wave frequency band to achieve bidirectional radiation characteristics within the working frequency band, and at the same time achieve high gain and low profile characteristics. The antenna array consists of two dipole antenna units with the same structure and a power divider. Among them, the dipole antenna unit structure includes a substrate integrated waveguide, a double-sided parallel strip line (DSPSL), a pair of long-arm dipoles etched with gaps and a guide oscillator, and the power divider includes a microstrip feeder, a balun conversion structure and a substrate integrated waveguide with a gap. Since the balun conversion structure can convert the unbalanced signal input by the microstrip line into a balanced signal, it is placed between the microstrip line and the substrate integrated waveguide, so that the two output ports of the power divider can achieve balanced feeding, that is, the two ends output signals with equal amplitude and opposite phases. This kind of millimeter wave planar dipole antenna array with bidirectional radiation characteristics, which places two identical dipole antenna unit structures back to back on both sides of a power divider, can be realized by PCB process processing as a whole, and is easy to integrate with active circuit systems.

[0005] A bidirectional radiating planar dipole antenna array operating in a millimeter wave frequency band of the present invention comprises a first metal sheet, a first dielectric substrate, a second dielectric substrate, a second metal sheet, a third dielectric substrate, and a third metal sheet;

[0006] The first metal sheet is attached to the upper surface of the first dielectric substrate; the second dielectric substrate is attached to the lower surface of the first dielectric substrate; the third dielectric substrate is located below the second dielectric substrate; the upper and lower sides of the second metal sheet are attached to the lower surface of the second dielectric substrate and the upper surface of the third dielectric substrate respectively, and the third metal sheet is attached to the lower surface of the third dielectric substrate.

[0007] Both sides of the second metal sheet and the third metal sheet are connected with metal connecting wires in a symmetrical structure, the other end of the metal connecting wire connected to the second metal sheet is connected to the top dipole arm, and is connected to the top dipole arm in an L-shaped structure, the other end of the metal connecting wire connected to the third metal sheet is connected to the bottom dipole arm, and is connected to the bottom dipole arm in an L-shaped structure, and gaps are etched on the top dipole arm and the bottom dipole arm;

[0008] The first metal sheet includes a microstrip line and a balun transformer connected to each other;

[0009] The third dielectric substrate is symmetrically structured with two rows of metallized through holes, the lower surface of the second metal sheet, the upper surface of the third metal sheet and the metallized through holes cooperate to form a substrate integrated waveguide, a rectangular hole is provided at the center of the second metal sheet, the microstrip line, the balun converter and the substrate integrated waveguide constitute a one-to-two power divider, and the one-to-two power divider has one signal input terminal and two signal output terminals; the above two signal output terminals are respectively connected to the signal input terminals of the corresponding dipole antenna units.

[0010] The millimeter wave dipole antenna unit refers to a millimeter wave dipole antenna unit composed of a top dipole arm and a bottom dipole arm on the same side.

[0011] Two identical millimeter-wave dipole antenna units are placed back to back to form a millimeter-wave planar dipole antenna, that is, an antenna array, to achieve bidirectional radiation characteristics.

[0012] The upper surface of the third dielectric substrate is symmetrically structured and provided with two guide vibrators.

[0013] Preferably, the balun converter comprises a U-shaped microstrip line and a rectangular patch, the bending portion of the U-shaped microstrip line is provided with a cut corner to improve the parasitic capacitance effect of the microstrip line, one end of the microstrip line is integrally formed with one end of the U-shaped microstrip line, and the other end of the U-shaped microstrip line is integrally formed with the rectangular patch.

[0014] Preferably, the upper and lower layers of metal connecting wires connected to the second metal sheet and the third metal sheet cooperate to form a double-sided parallel strip line, and the vertical arms of the top dipole arm and the bottom dipole arm are oriented in opposite directions. The linear array composed of two dipole antenna units is used for bidirectional radiation in the millimeter wave frequency band.

[0015] Preferably, a strip-shaped rectangular hole is etched at the center of the second metal sheet.

[0016] Preferably, the dipole arm length of the millimeter wave planar dipole antenna is 1.5λ g , where λ g is the wavelength corresponding to the center operating frequency of the dipole antenna.

[0017] Preferably, the slit is etched at the middle position of each dipole arm and has a width of 0.1 mm.

[0018] Preferably, the distance between the director oscillator and the dipole arm is about λ g / 4.

[0019] Preferably, the millimeter-wave planar dipole antenna is fed by a one-to-two power divider, and each output port of the one-to-two power divider is directly connected to the millimeter-wave planar dipole antenna.

[0020] The present invention has the following advantages:

[0021] (1) The antenna adopts a dipole structure and etches a pair of slots at appropriate positions, so that the antenna can work in half-wavelength mode and 1.5 times wavelength mode at the same time, greatly improving the impedance bandwidth of the antenna.

[0022] (2) The antenna converts the unbalanced signal fed by the microstrip line into a balanced signal by using a balun conversion structure, so that the two output ports of the power divider output signals with equal amplitudes and opposite phases, thus achieving balanced feeding.

[0023] (2) The antenna achieves bidirectional radiation characteristics by placing two identical antenna unit structures back to back on both sides of the power divider.

[0024] (3) The antenna covers the millimeter wave frequency band of 5G and is a planar dipole structure with a low profile height and easy integration with planar circuits.

[0025] (4) This millimeter-wave planar dipole antenna array, which places two identical dipole antenna unit structures back to back on both sides of a power divider, realizes bidirectional radiation characteristics. The whole can be realized through PCB processing and is easy to integrate with active circuit systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the three-dimensional structure of the present invention;

[0027] Figure 2 is a side view of the present invention;

[0028] Figure 3 is a top view of the present invention;

[0029] Figure 4 is a top view of the millimeter wave dipole antenna unit of the present invention;

[0030] Figure 5 is a side view of a power distributor of the present invention;

[0031] Figure 6 It is a reflection coefficient and gain simulation diagram of the millimeter wave dipole antenna unit of the present invention;

[0032] Figure 7 It is an S parameter simulation diagram of the power divider of the present invention;

[0033] Figure 8 It is a simulation diagram of the phase difference between two output ports of the power divider of the present invention;

[0034] Fig. 9It is a reflection coefficient and gain simulation diagram of the millimeter wave bidirectional radiation planar dipole antenna array of the present invention;

[0035] Fig.10 It is a comparison of the simulation results of the main polarization and cross polarization of the E-plane and H-plane of the present invention at 26GHz;

[0036] Fig.11 It is a comparison of the simulation results of the main polarization and cross polarization of the E-plane and H-plane of the present invention at 28GHz;

[0037] Fig.12 It is a comparison of the simulation results of the main polarization and cross polarization of the E-plane and H-plane of the present invention at 30GHz;

[0038] Fig.13 It is a comparison of the simulation results of the main polarization and cross polarization of the E-plane and H-plane of the present invention at 32GHz;

[0039] Markings in the figure: M1-first metal sheet, S1-first dielectric substrate, S2-second dielectric substrate, M2-second metal sheet, S3-third dielectric substrate, M3-third metal sheet, 1-director, 2-metallized through hole, 3-gap, 4-connecting metal wire, 5-rectangular hole, 6-one-to-two power divider, 7-microstrip line, 8-balun converter, 9-top dipole arm, 10-bottom dipole arm, 11-substrate integrated waveguide. DETAILED DESCRIPTION

[0040] The present invention is further analyzed below in conjunction with specific embodiments.

[0041] The present invention provides a bidirectional radiating planar dipole antenna array operating in the millimeter wave frequency band, such as Figure 1 As shown, the bidirectional radiating planar dipole antenna array operating in the millimeter wave frequency band is a multi-layer vertical arrangement structure, including a first metal sheet M1, a first dielectric substrate S1, a second dielectric substrate S2, a second metal sheet M2, a third dielectric substrate S3, and a third metal sheet M3; wherein the first dielectric substrate S1 and the third dielectric substrate S3 adopt Rogers Duriod 5880, with a dielectric constant of 2.2, a loss tangent of 0.0009, and a thickness of 0.508 mm, and the second dielectric substrate S2 adopts Rogers RO4450B, with a dielectric constant of 3.54, a loss tangent of 0.004, and a thickness of 0.1 mm;

[0042] Further, such as Figure 2 As shown, the third dielectric substrate S3 is symmetrically provided with two rows of metallized through holes 2, and the lower surface of the second metal sheet M2, the upper surface of the third metal sheet M3 and the metallized through holes 2 cooperate to form a substrate integrated waveguide (SIW) 11.

[0043] like Figure 3 , 4 , 5, the first metal sheet M1 is located on the upper surface of the first dielectric substrate S1, and the first metal sheet M1 includes a microstrip line 7 and a balun converter 8 connected to each other; the microstrip line 7, the balun converter 8 and the substrate integrated waveguide 11 form a one-to-two power divider 6;

[0044] The second dielectric substrate S2 is located on the lower surface of the first dielectric substrate S1 and is used to bond the first dielectric substrate S1 and the third dielectric substrate S3;

[0045] The second metal sheet M2 is located on the lower surface of the second dielectric substrate S2 and the upper surface of the third dielectric substrate S3, and the second metal sheet M2 includes the top dipole arm 9 of the millimeter wave planar dipole antenna, the upper surface metallization layer of the substrate integrated waveguide 11, the bidirectional parallel strip line (DSPSL) 4 and the guide oscillator 1. The upper surface of the substrate integrated waveguide 11 is etched with a strip-shaped rectangular hole 5.

[0046] The third metal sheet M3 is located on the lower surface of the third dielectric substrate S3, and includes a bottom dipole arm 10 and a bottom surface metallization layer of a substrate integrated waveguide 11. The bottom dipole arm and the top dipole arm constitute a complete millimeter wave planar dipole antenna. The bottom surface metallization layer of the third metal sheet M3, the upper surface metal layer of the second metal sheet M2, and the metallized through hole 2 of the third dielectric substrate S3 constitute a complete substrate integrated waveguide 11.

[0047] The bottom dipole arm and the top dipole arm both have an etched gap 3, and the gap width is 0.1 mm;

[0048] The millimeter wave bidirectional radiation planar dipole antenna array is a linear array composed of two dipole antenna units, which is used for bidirectional radiation in the millimeter wave frequency band. These millimeter wave dipole units are fed by substrate integrated waveguides and are placed back to back on both sides of the one-to-two power divider 6 at a certain distance;

[0049] The one-to-two power divider 6 is composed of a microstrip line 7 of a first metal sheet M1, a balun converter 8, and a substrate integrated waveguide with a rectangular hole 5, as shown in FIG. Figure 5 As shown, it has one signal input terminal Port1 and two signal output terminals Port2 and Port3; the above two signal output terminals are respectively connected to the signal input terminals of the corresponding dipole antenna units.

[0050] The specific working principle of the above embodiment is as follows: when the antenna works in the millimeter wave frequency band, the signal is transmitted from the microstrip line, and a balun conversion structure is used to realize balanced distribution of the signal on the two branch microstrip lines, and finally coupled to the slot, and transmitted from the slot to the two ends of the substrate integrated waveguide (SIW) to realize balanced feeding, that is, signals with equal amplitude and opposite phase are transmitted to the dipole antenna units at both ends respectively, so as to realize bidirectional radiation characteristics. The double-sided parallel strip line (DSPSL) is a kind of switching structure between the dipole and the substrate integrated waveguide, and its characteristic impedance is very close to the input impedance of the dipole in the antenna unit structure and the wave impedance of the substrate integrated waveguide. Therefore, the double-sided parallel strip line can directly connect the dipole antenna and the substrate integrated waveguide without the need for a switching structure with a gradually changing width. The millimeter wave dipole antenna unit etches a slot at an appropriate position on the dipole arm, so that the dipole antenna works in the half-wavelength mode and the 1.5 times wavelength mode at the same time, introduces a new resonance point, and the impedance matching of the low-frequency part is significantly improved, thereby significantly widening the working bandwidth. Placing a director in front of each of the two end dipoles can not only increase the gain of the antenna unit, but also improve the directivity of the antenna.

[0051] Based on the above embodiment, further description is given through the following simulation:

[0052] Figure 6 This is a simulation diagram of the reflection coefficient and gain of the millimeter wave dipole antenna unit of the present invention. The -10 dB frequency band is between 19.8 and 38.6 GHz, and the maximum gain within the frequency band is 7.3 dBi. Figure 7 It is the S parameter simulation diagram of the power divider of the present invention.

[0053] It can be seen that the reflection coefficient of the power divider of this embodiment is less than -10dB in the frequency range of 23.2GHz to 40.4GHz, and is lower than -20dB in most operating frequency bands, indicating that most of the energy is basically non-reflected. At the same time, the transmission coefficients of the two output ports are very similar and almost the same.

[0054] Figure 8 It is a simulation diagram of the phase difference between the two output ports of the power divider of the present invention.

[0055] It can be seen that in this embodiment, within the entire working frequency band, the port phase difference is maintained within 180°±1.2°, indicating that the power divider implements the distribution principle of equal amplitude and opposite phase.

[0056] Fig. 9 The reflection coefficient and gain curves of the present invention designed for simulation working in the millimeter wave frequency band are shown, the -10dB frequency band is around 26.5-38GHz, and the gain within the frequency band is above 5dBi. Fig.10 , 11, 12, and 13 are comparisons of simulation results of the main polarization and cross polarization of the E-plane and H-plane of the millimeter-wave antenna array of the present invention at frequencies of 26 GHz, 28 GHz, 30 GHz, and 32 GHz, respectively.

[0057] It can be seen that the millimeter wave antenna array provided in this embodiment has a relatively symmetrical radiation pattern, indicating that it has good bidirectional radiation performance.

[0058] The above is only a preferred embodiment of the present invention, and does not limit the embodiments of the present invention. It should be pointed out that for those skilled in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should be included in the scope of protection of the claims of the present invention.

Claims

1. A bidirectional radiating planar dipole antenna array operating in the millimeter wave frequency band, characterized in that: It includes a first metal sheet, a first dielectric substrate, a second dielectric substrate, a second metal sheet, a third dielectric substrate, and a third metal sheet; The first metal sheet is attached to the upper surface of the first dielectric substrate; The second dielectric substrate is attached to the lower surface of the first dielectric substrate; the third dielectric substrate is located below the second dielectric substrate; the upper and lower sides of the second metal sheet are attached to the lower surface of the second dielectric substrate and the upper surface of the third dielectric substrate respectively, and the third metal sheet is attached to the lower surface of the third dielectric substrate. Both sides of the second metal sheet and the third metal sheet are connected with metal connecting wires in a symmetrical structure, the other end of the metal connecting wire connected to the second metal sheet is connected to the top dipole arm, and is connected to the top dipole arm in an L-shaped structure, the other end of the metal connecting wire connected to the third metal sheet is connected to the bottom dipole arm, and is connected to the bottom dipole arm in an L-shaped structure, and gaps are etched on the top dipole arm and the bottom dipole arm; The top dipole arm and the bottom dipole arm on the same side form a millimeter wave dipole antenna unit, and two identical millimeter wave dipole antenna units are placed back to back to form a millimeter wave planar dipole antenna; The first metal sheet includes a microstrip line and a balun transformer connected to each other; The third dielectric substrate is provided with two rows of metallized through holes in a symmetrical structure, the lower surface of the second metal sheet, the upper surface of the third metal sheet and the metallized through holes cooperate to form a substrate integrated waveguide, and the microstrip line, the balun converter and the substrate integrated waveguide form a one-to-two power divider; The upper surface of the third dielectric substrate is symmetrically structured and provided with two guiding vibrators.

2. A bidirectional radiating planar dipole antenna array operating in the millimeter wave frequency band according to claim 1, characterized in that: The balun converter comprises a U-shaped microstrip line and a rectangular patch, wherein the bending portion of the U-shaped microstrip line is provided with a cut corner, one end of the microstrip line is integrally formed with one end of the U-shaped microstrip line, and the other end of the U-shaped microstrip line is integrally formed with the rectangular patch.

3. The bidirectional radiating planar dipole antenna array operating in the millimeter wave frequency band according to claim 1, characterized in that: The upper and lower layers of metal connecting wires connected to the second metal sheet and the third metal sheet cooperate to form a double-sided parallel strip line, and the vertical arms of the top dipole arm and the bottom dipole arm are oriented in opposite directions.

4. The bidirectional radiating planar dipole antenna array operating in the millimeter wave frequency band according to claim 1, characterized in that: A strip-shaped rectangular hole is etched at the center of the second metal sheet.

5. The bidirectional radiating planar dipole antenna array operating in the millimeter wave frequency band according to claim 1, characterized in that: The dipole arm length of the millimeter wave planar dipole antenna is 1.5λ g , where λ g is the wavelength corresponding to the center operating frequency of the dipole antenna.

6. A bidirectional radiating planar dipole antenna array operating in the millimeter wave frequency band according to claim 5, characterized in that: The slit is etched at the middle position of each dipole arm and has a width of 0.1 mm.

7. The bidirectional radiating planar dipole antenna array operating in the millimeter wave frequency band according to claim 5, characterized in that: The distance between the director and the dipole arm is λ g / 4.

8. The bidirectional radiating planar dipole antenna array operating in the millimeter wave frequency band according to claim 1, characterized in that: The millimeter wave planar dipole antenna is fed by a one-to-two power divider, and each output port of the one-to-two power divider is directly connected to the millimeter wave planar dipole antenna.

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