Millimeter wave array planar coupling ring decoupling structure and antenna array

Abstract

The present invention provides a millimeter-wave array planar coupled annular decoupling structure and an antenna array. An annular decoupling structure is added between two series-fed patch antennas, and the two are vertically distributed. Capacitive coupling of signals is performed between the annular decoupling structure, which is very close to the antenna feed line, and the series-fed patch antennas. After an indirect coupling signal is received from the first series-fed patch antenna, it is introduced into the second series-fed patch antenna through the coupling line. The length of the annular decoupling structure is adjusted to control the indirect coupling signal and the direct coupling signal to achieve a 180° phase difference, thereby completing the reverse phase cancellation of the indirect coupling signal and the direct coupling signal. The annular decoupling structure adopts an upper and lower symmetrical structure, and the currents on the upper and lower transmission paths are in opposite directions. Therefore, the influence of the additional introduction of the decoupling structure on the amplitude and phase consistency in the radiation far field can be suppressed to the greatest extent.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle-mounted antennas, and in particular to a millimeter wave array planar coupled annular decoupling structure and an antenna array. Background Art

[0002] Currently, due to limitations in millimeter-wave radar size and manufacturing processes, improvements to millimeter-wave array performance can only be achieved using planar structures, meaning they can only be printed on the antenna substrate along with the antenna. This means that many of the techniques used for low-frequency antennas, such as microwaves, cannot be used in millimeter-wave radar arrays.

[0003] Among the more established solutions for enhancing millimeter-wave array isolation, mushroom-type EBG structures and dummy antennas are the most widely used. The mushroom-type EBG structure, by employing equivalent capacitors and inductors, can act like a filter, blocking plane wave coupling within a specific frequency range. However, due to the small array spacing and the periodic nature of the EBG structure, the antenna spacing is too small, significantly reducing the antenna's beamwidth and scanning angle. The dummy antenna solution, on the other hand, inserts a dummy antenna identical to the array antennas between them. This additional dummy antenna introduces additional coupling. By properly adjusting the feed lines and lumped element loads at the dummy antenna ports, the phase and amplitude of the dummy antenna's reflections are adjusted to cancel out the original coupling, thereby enhancing array isolation. This solution not only enhances isolation but also effectively expands the antenna pattern's beamwidth. However, it also has significant drawbacks: First, it requires the use of lumped components, increasing costs. Second, while increasing the beamwidth, it significantly reduces the maximum gain, and this cannot be improved by adjusting the dummy antenna. Third, the isolation improvement effect is limited. The length of the dummy antenna feed line and the resistance of the lumped load components require complex calculations, and the relevant resistance values may not be found. However, since the above structures all change the antenna's spatial wave or surface wave, the amplitude and phase consistency deteriorates to varying degrees. This is a common problem with existing decoupling structures. Since the decoupling structure itself participates in radiation or affects the radiation of the antenna itself, it will more or less deteriorate the amplitude and phase consistency of the antenna array, making it difficult to balance the isolation index and the amplitude and phase consistency index. Summary of the Invention

[0004] In response to the above-mentioned technical problem that it is difficult to take into account both the isolation index and the amplitude and phase consistency index, the present invention proposes a millimeter wave array planar coupled ring decoupling structure and antenna array. Since the coupling between antennas mainly comes from the direct coupling of the antenna radiator, the present invention introduces an additional structure to introduce part of the energy on the antenna feed line to another antenna. By adjusting the length of the transmission line of this structure, the phase of the indirect coupling signal is changed, so that it cancels out the direct coupling signal between the antennas in the opposite direction, thereby achieving improved isolation.

[0005] Specifically, the millimeter wave array planar coupled annular decoupling structure described in the present invention comprises at least: an annular transmission line in the middle, and a first coupling line and a second coupling line connected at both ends by connecting lines.

[0006] The coupling line is a vertically symmetrical structure about a horizontal central axis, and the horizontal lengths of the annular transmission line and the connecting line are adjusted according to the phase difference between the indirect coupling signal and the direct coupling signal.

[0007] The first coupling line and the second coupling line are symmetrically distributed around the vertical central axis of the transmission line.

[0008] The lengths of the first coupling line and the second coupling line are preset values.

[0009] The transmission line includes an upper transmission line and a lower transmission line that are symmetrical to each other, and the currents transmitted between the upper transmission line and the lower transmission line are in opposite directions.

[0010] The line widths of the upper transmission line and the lower transmission line are distributed in a gradual manner from small to large from the middle to both sides.

[0011] As another preferred embodiment, the present invention also provides a millimeter wave array planar coupling antenna array, comprising at least: at least two series-fed patch antennas etched on the upper surface of a dielectric substrate, a ring-shaped decoupling structure added between the series-fed patch antennas, the series-fed patch antenna and the ring-shaped decoupling structure being spaced apart by a preset distance and being vertically distributed; after the indirect coupling signal is received from the first series-fed patch antenna, it is introduced into the second series-fed patch antenna through the ring-shaped decoupling structure, and the length of the ring-shaped decoupling structure is adjusted to control the indirect coupling signal and the direct coupling signal to achieve a phase difference of 180°, thereby completing the reverse cancellation of the indirect coupling signal and the direct coupling signal.

[0012] The first coupling line and the second coupling line are in the shape of long strips and are parallel to the feed line of the first serial-fed patch antenna and the feed line of the second serial-fed patch antenna, respectively.

[0013] The feed patch antenna is composed of patch radiating units that gradually increase in size from the middle to the two sides. The patch radiating units are connected by feed lines, and the patch radiating units are cross-distributed on the left and right sides of the feed lines.

[0014] The annular decoupling structure is arranged at an end of the series-fed patch antenna away from the patch radiation unit.

[0015] In summary, the present invention provides a millimeter-wave array planar coupled annular decoupling structure and an antenna array, which adds an annular decoupling structure between two series-fed patch antennas, and the two are distributed vertically; the annular decoupling structure that is very close to the antenna feed line is used to capacitively couple the signal with the series-fed patch antenna, and after the indirect coupling signal is received from the first series-fed patch antenna, it is introduced into the second series-fed patch antenna through the coupling line, and the length of the annular decoupling structure is adjusted to control the indirect coupling signal and the direct coupling signal to achieve a phase difference of 180°, thereby completing the reverse phase cancellation of the indirect coupling signal and the direct coupling signal. The annular decoupling structure adopts an upper and lower symmetrical structure, and the currents on the upper and lower transmission paths are in opposite directions, so that the influence of the additional introduction of the decoupling structure on the amplitude and phase consistency in the far field can be suppressed to the greatest extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of a millimeter wave array planar coupled antenna array described in the present invention.

[0017] Figure 2 for Figure 1 Schematic diagram of the ring decoupling structure described in .

[0018] Figure 3 for Figure 2 Schematic diagram of current transmitted between the upper transmission line and the lower transmission line of the ring decoupling structure described in .

[0019] Figure 4 This is a diagram showing the isolation improvement effect of the millimeter wave array planar coupled ring decoupling structure described in the present invention.

[0020] Figure 5 This is a comparison diagram of the front and rear amplitude consistency of the millimeter wave loaded annular decoupling structure described in the present invention.

[0021] Figure 6 The antenna radiation pattern effects of the millimeter wave array before and after the planar coupling ring decoupling structure is loaded are compared.

[0022] Among them, 1-dielectric substrate; 2-series-fed patch antenna; 21-first series-fed patch antenna; 22-second series-fed patch antenna; 3-annular decoupling structure; 31-annular transmission line; 311-upper transmission line; 312-lower transmission line; 32-connecting line; 33-first coupling line; 34-second coupling line. DETAILED DESCRIPTION

[0023] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0024] like Figure 1 As shown, the present invention proposes a millimeter wave array planar coupled annular decoupling structure. The overall effect diagram is shown. By adding a coupling line between two series-fed patch antennas, and the two are distributed at 90 degrees; the annular decoupling structure that is very close to the antenna feed line is used to capacitively couple the signal with the series-fed patch antenna. Since the coupling between antennas mainly comes from the direct coupling of the antenna radiator, including the surface wave coupling and space wave coupling of the antenna, and the coupling on the series-fed patch antenna can be ignored. Therefore, the present invention introduces a ring-shaped decoupling structure to introduce part of the energy on the series-fed patch antenna into another series-fed patch antenna, and by adjusting the length of the transmission line of the coupled annular decoupling junction, a 180° phase difference between the indirect coupling signal and the direct coupling signal is achieved. The indirectly introduced phase is changed so that it cancels out the direct coupling signal between the antennas in the opposite direction, thereby improving the isolation.

[0025] Specifically, the millimeter wave array planar coupling ring decoupling structure of the present invention is as follows: Figure 1 As shown, it at least includes: at least two series-fed patch antennas etched on the upper surface of the dielectric substrate, a ring-shaped decoupling structure is added between the series-fed patch antennas, the series-fed patch antenna and the ring-shaped decoupling structure are separated by a preset distance and the two are vertically distributed; after the indirect coupling signal is received from the first series-fed patch antenna, it is introduced into the second series-fed patch antenna through the ring-shaped decoupling structure, and energy is transferred by coupling, which can optimize the isolation without affecting the antenna port matching and return loss, and the placement position is flexible.

[0026] Further adjusting the length of the annular decoupling structure controls the phase difference of the indirect and direct coupling signals to 180°, achieving reverse cancellation of the indirect and direct coupling signals. This structure, etched directly onto the dielectric substrate, offers a simple structure, ease of fabrication, and convenient parameter adjustment. It also directly utilizes the energy coupled by the feeder for decoupling, without affecting the antenna's radiation pattern, ensuring the antenna's radiation performance.

[0027] like Figure 2 As shown, the millimeter wave array planar coupled annular decoupling structure described in the present invention comprises at least: a ring transmission line in the middle, and a first coupling line and a second coupling line connected at both ends by connecting lines.

[0028] Furthermore, the coupling line is a vertically symmetrical structure about a horizontal central axis, and the horizontal lengths of the annular transmission line and the connecting line are adjusted according to the phase difference between the indirect coupling signal and the direct coupling signal, thereby not destroying the amplitude and phase consistency of the antenna array.

[0029] The horizontal lengths of the ring transmission line and the connecting line are adjusted according to the phase difference between the indirect coupling signal and the direct coupling signal.

[0030] Furthermore, the first coupling line and the second coupling line are symmetrically distributed around the vertical central axis of the transmission line.

[0031] Furthermore, the first coupling line and the second coupling line are in the shape of long strips and are parallel to the first string of antenna feed lines and the second string of antenna feed lines, respectively.

[0032] Furthermore, the lengths of the first coupling line and the second coupling line are preset values.

[0033] Furthermore, the transmission line includes an upper transmission line and a lower transmission line that are symmetrical to each other, and the currents transmitted between the upper transmission line and the lower transmission line are in opposite directions. Figure 3 As shown, the structure adopts an upper and lower symmetrical design, so that the radiation effects generated by the upper and lower current paths can offset each other, thereby not destroying the amplitude and phase consistency of the antenna array.

[0034] Furthermore, the line widths of the upper transmission line and the lower transmission line are distributed in a gradual manner from small to large from the middle to both sides.

[0035] As another preferred embodiment, the present invention also provides a millimeter wave array planar coupling antenna array, comprising at least: at least two series-fed patch antennas etched on the upper surface of a dielectric substrate, a ring-shaped decoupling structure added between the series-fed patch antennas, the series-fed patch antenna and the ring-shaped decoupling structure being spaced apart by a preset distance and being vertically distributed; after the indirect coupling signal is received from the first series-fed patch antenna, it is introduced into the second series-fed patch antenna through the ring-shaped decoupling structure, and the length of the ring-shaped decoupling structure is adjusted to control the indirect coupling signal and the direct coupling signal to achieve a phase difference of 180°, thereby completing the reverse cancellation of the indirect coupling signal and the direct coupling signal.

[0036] Furthermore, the first coupling line and the second coupling line are in the shape of long strips and are parallel to the feed line of the first serial-fed patch antenna and the feed line of the second serial-fed patch antenna, respectively.

[0037] Furthermore, the feed patch antenna is composed of patch radiating units that gradually increase in size from the middle to both sides, and each patch radiating unit is connected by a feed line. The patch radiating units are cross-distributed on the left and right sides of the feed line.

[0038] Furthermore, the annular decoupling structure is arranged at an end of the series-fed patch antenna away from the patch radiation unit.

[0039] Specifically, in order to further illustrate the effectiveness of the above antenna design, the millimeter wave array planar coupled ring decoupling structure of the present invention is simulated, wherein:

[0040] Figure 4 This is a diagram showing the isolation improvement effect of the millimeter-wave array planar coupled ring decoupling structure of the present invention. It can be seen that the improved millimeter-wave array antenna can effectively improve the isolation.

[0041] Figure 5 This is the amplitude-phase consistency of the millimeter-wave array planar coupled ring decoupling structure of the present invention, where the dotted line represents the unloaded decoupling structure and the solid line represents the loaded decoupling structure. As shown in the figure, the structure does not destruct the amplitude-phase consistency, and there is almost no difference before and after the decoupling structure is loaded.

[0042] Figure 6 This is the radiation pattern of the antenna with the millimeter-wave array planar coupled ring decoupling structure. It can be seen that the introduction of the structure described in the present invention has almost no effect on the radiation pattern of the antenna, and can maintain the original radiation performance of the antenna.

[0043] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A millimeter wave array planar coupling ring decoupling structure, characterized in that: The annular decoupling structure comprises at least: an annular transmission line in the middle, and a first coupling line and a second coupling line connected at both ends by connecting lines; The coupling line is a vertically symmetrical structure with a horizontal central axis, and the horizontal lengths of the annular transmission line and the connecting line are adjusted according to the phase difference between the indirect coupling signal and the direct coupling signal; The transmission line comprises an upper transmission line and a lower transmission line which are symmetrical to each other, and the currents transmitted between the upper transmission line and the lower transmission line are in opposite directions; The line widths of the upper transmission line and the lower transmission line are distributed in a gradual manner from small to large from the middle to both sides.

2. The millimeter wave array planar coupling ring decoupling structure according to claim 1, characterized in that: The first coupling line and the second coupling line are symmetrically distributed around the vertical central axis of the transmission line.

3. The millimeter wave array planar coupling ring decoupling structure according to claim 2, characterized in that: The lengths of the first coupling line and the second coupling line are preset values.

4. A millimeter wave array planar coupled antenna array, characterized in that: At least: At least two series-fed patch antennas are etched on the upper surface of a dielectric substrate, and a ring-shaped decoupling structure as described in any one of claims 1 to 3 is added between the series-fed patch antennas, the series-fed patch antenna and the ring-shaped decoupling structure are separated by a preset spacing and the two are vertically distributed; after an indirect coupling signal is received from the first series-fed patch antenna, it is introduced into the second series-fed patch antenna through the ring-shaped decoupling structure, and the length of the ring-shaped decoupling structure is adjusted to control the indirect coupling signal and the direct coupling signal to achieve a phase difference of 180°, thereby completing the reverse cancellation of the indirect coupling signal and the direct coupling signal.

5. The millimeter wave array planar coupled antenna array according to claim 4, characterized in that: The first coupling line and the second coupling line are in the shape of long strips and are parallel to the feed line of the first serial-fed patch antenna and the feed line of the second serial-fed patch antenna, respectively.

6. The millimeter wave array planar coupled antenna array according to claim 5, characterized in that: The series-fed patch antenna is composed of patch radiating units that gradually decrease in size from the middle to both sides. The patch radiating units are connected by feeders, and the patch radiating units are cross-distributed on the left and right sides of the feeder.

7. The millimeter wave array planar coupled antenna array according to claim 6, characterized in that: The annular decoupling structure is arranged at an end of the series-fed patch antenna away from the patch radiation unit.

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