Low Profile Room Antenna

Abstract

The present invention provides a low-profile room-separated antenna, which relates to the field of antenna technology. The low-profile room-separated antenna includes: a first dielectric substrate, a second dielectric substrate, a third dielectric substrate and a fourth dielectric substrate connected in sequence, each of which has a compact structure to achieve a low-profile effect. Moreover, since a plurality of first short-circuit posts, a plurality of second short-circuit posts and a plurality of third short-circuit posts are distributed in a semicircular shape, the circularity of the directional pattern of the radiation signal can be improved. Due to the presence of the second resonant cavity, the function of frequency selection filtering is realized, so that the low-profile room-separated antenna integrates the heterodyne decoupling capability. Compared with the existing quasi-omnidirectional antenna, the low-profile room-separated antenna has the advantages of high performance, low profile and simple structure in addition to realizing the out-of-band harmonic suppression function, and realizes the integrated integration of antenna and filter and functional fusion.

Description

Technical Field

[0001] The present invention relates to the field of antenna technology, and in particular to a low-profile indoor antenna. Background Art

[0002] With the rapid development of communication technology, quasi-isotropic antennas are widely used in wireless communication systems that require omnidirectional coverage, such as mobile communication base stations, broadcasting and television transmission systems, etc., due to their relatively uniform omnidirectional radiation characteristics.

[0003] In the prior art, quasi-isotropic room antennas are usually relatively complex in structure and have high requirements for cross-sectional height. By using the magnetic wall radiation characteristics of substrate integrated waveguides, a magnetic dipole antenna with high circularity of the directional pattern, simple structure and low cross-section can be designed.

[0004] In actual applications, due to the diversity of working modes and frequencies of magnetic dipole antennas, the communication system after integrating them with the RF transceiver module is often challenged by harmonic interference and forms heterodyne coupling. Traditional designs usually adopt the form of cascading filters to reduce heterodyne coupling.

[0005] However, the indoor antenna designed by the above method has a complex structure, which increases the loss of the communication system and increases the difficulty of integrating the communication system. Summary of the invention

[0006] The present invention provides a low-profile indoor antenna to solve the defects existing in the related art.

[0007] The present invention provides a low-profile indoor antenna, comprising: a first dielectric substrate, a second dielectric substrate, a third dielectric substrate and a fourth dielectric substrate connected in sequence;

[0008] A first patch is arranged on the first dielectric substrate, and a plurality of first short-circuit posts distributed in a semicircular shape are arranged in the first dielectric substrate;

[0009] A second patch is arranged on the second dielectric substrate, and a plurality of second short-circuit posts distributed in a semicircular pattern are arranged in the second dielectric substrate; the plurality of first short-circuit posts and the plurality of second short-circuit posts are respectively located on two sides of the second patch;

[0010] A metal floor is arranged on the third dielectric substrate, a plurality of third short-circuit posts distributed in a semicircular shape are arranged in the third dielectric substrate, and the plurality of second short-circuit posts and the plurality of third short-circuit posts are both located between the second patch and the metal floor;

[0011] The plurality of first short-circuit posts, the plurality of second short-circuit posts and the plurality of third short-circuit posts correspond to each other one by one;

[0012] A coupling gap is formed on the second patch, a feeding through hole corresponding to the coupling gap is formed on the third dielectric substrate and the metal floor, and a first feeding structure is arranged in the feeding through hole;

[0013] A second feeding structure is disposed on the fourth dielectric substrate, the first feeding structure is in contact with the second feeding structure, and the second feeding structure is used to receive an input signal;

[0014] A first resonant cavity is formed between the first patch and the second patch, and a second resonant cavity is formed between the second patch and the metal floor. The first resonant cavity and the second resonant cavity are used to radiate signals.

[0015] According to a low-profile room-type antenna provided by the present invention, the first feeding structure includes an in-hole feeding probe and a feeding disk connected to the in-hole feeding probe;

[0016] The in-hole feeding probe is disposed in the feeding through hole and contacts the second feeding structure;

[0017] The feeding disk is located in the second resonant cavity.

[0018] According to a low-profile room antenna provided by the present invention, the center of the in-hole feeding probe and the center of the feeding disk are on the same axis.

[0019] According to a low-profile room-type antenna provided by the present invention, the second feeding structure is a T-shaped feeding structure composed of multiple sections of high and low impedance lines, the feeding through hole includes a first feeding through hole and a second feeding through hole, and the coupling slot includes a first coupling slot and a second coupling slot;

[0020] The vertical portion of the T-shaped feeding structure is used to receive the input signal;

[0021] The horizontal portion of the T-shaped feeding structure is used to output two output signals, and the first end and the second end of the horizontal portion of the T-shaped feeding structure are respectively provided with a first feeding probe and a second feeding probe;

[0022] The first end of the horizontal portion of the T-shaped feeding structure, the first feeding through hole and the first coupling slot correspond to each other one by one, and the first feeding probe is electrically connected to the in-hole feeding probe in the first feeding through hole;

[0023] The second end of the horizontal portion of the T-shaped feeding structure, the second feeding through hole and the second coupling slot correspond one to one, and the second feeding probe is electrically connected to the in-hole feeding probe in the second feeding through hole.

[0024] According to a low-profile room-space antenna provided by the present invention, the position of the coupling slot on the second patch is based on the antenna mode TM21 and TM 02 The intersection points of the virtual electric walls are determined.

[0025] According to a low-profile room antenna provided by the present invention, the first patch and the second patch are both semicircular in shape and have the same size.

[0026] According to a low-profile room antenna provided by the present invention, the coupling slot is rectangular, and the angle between the long side of the coupling slot and the straight side of the second patch is 45°.

[0027] According to a low-profile room antenna provided by the present invention, the first patch is connected to the first dielectric substrate and the plurality of first short-circuit posts by welding or conductive glue;

[0028] The second patch is connected to the second dielectric substrate and the plurality of second short-circuit posts by welding or conductive adhesive.

[0029] According to a low-profile room antenna provided by the present invention, the first dielectric substrate, the second dielectric substrate, the third dielectric substrate and the fourth dielectric substrate are connected by stacking or conductive adhesive.

[0030] According to a low-profile indoor antenna provided by the present invention, the first dielectric substrate, the second dielectric substrate, the third dielectric substrate and the fourth dielectric substrate are all flame-retardant copper-clad laminates;

[0031] The first patch, the second patch and the metal floor are all copper plates or aluminum plates.

[0032] The low-profile room-based antenna provided by the present invention includes: a first dielectric substrate, a second dielectric substrate, a third dielectric substrate and a fourth dielectric substrate connected in sequence, each of which has a compact structure and achieves a low-profile effect. Moreover, since the plurality of first short-circuit posts, the plurality of second short-circuit posts and the plurality of third short-circuit posts are distributed in a semicircular shape, the circularity of the radiated signal pattern can be improved. Due to the presence of the second resonant cavity, the function of frequency selection filtering is realized, so that the low-profile room-based antenna integrates the heterodyne decoupling capability. Compared with the existing quasi-omnidirectional antenna, the low-profile room-based antenna, in addition to realizing the out-of-band harmonic suppression function, also has the advantages of high performance, low profile and simple structure, realizing the integrated integration of antenna and filter and functional fusion. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the present invention or related technologies, the drawings required for use in the embodiments or related technical descriptions are briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0034] Figure 1 It is a structural schematic diagram of the low-profile room antenna provided by the present invention.

[0035] Figure 2 It is a schematic diagram of the scattering parameters and actual gain of the low-profile indoor antenna provided by the present invention.

[0036] Figure 3 It is a schematic diagram of the radiation direction of the low-profile indoor antenna provided by the present invention. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are 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 creative work are within the scope of protection of the present invention.

[0038] Since the structure of the magnetic dipole room antenna with high circularity, low profile and reduced hetero-frequency coupling provided in the prior art is complex, the loss of the communication system is increased and the integration difficulty of the communication system is increased. Therefore, a low-profile room antenna is provided in an embodiment of the present invention.

[0039] Figure 1 FIG. 1 is a schematic diagram of a low-profile indoor antenna provided in an embodiment of the present invention. Figure 1 As shown, the low-profile indoor antenna includes: a first dielectric substrate 120, a second dielectric substrate 220, a third dielectric substrate 320 and a fourth dielectric substrate 420 connected in sequence.

[0040] The first patch 110 is disposed on the first dielectric substrate 120, and the first patch 110 can be bonded to the first dielectric substrate 120. The first dielectric substrate 120 can be provided with a plurality of first shorting posts 130 distributed in a semicircular pattern, and the first shorting posts 130 can be evenly distributed in a semicircular pattern, and the sizes of the first shorting posts 130 are the same.

[0041] The first dielectric substrate 120 , the first patch 110 , and the first short-circuit posts 130 may constitute the first layer 100 of the low-profile room antenna.

[0042] A second patch 210 is disposed on the second dielectric substrate 220, and the second patch 210 can be bonded to the second dielectric substrate 220. A plurality of second short-circuit posts 230 are disposed in a semicircular pattern in the second dielectric substrate 220, and each second short-circuit post 230 can be evenly distributed in a semicircular pattern, and each second short-circuit post 230 has the same size. The size of each first short-circuit post 130 and each second short-circuit post 230 can be the same or different, and is not specifically limited here. In order to reduce processing costs, the size of each first short-circuit post 130 and each second short-circuit post 230 can be set to be the same.

[0043] Each first short-circuit post 130 and each second short-circuit post 230 are respectively located on two sides of the second patch 210 , for example Figure 1 In the embodiment, the first patch 110 is disposed on the upper surface of the first dielectric substrate 120 , and the second patch 210 is disposed on the upper surface of the second dielectric substrate 220 .

[0044] The second dielectric substrate 220 , the second patch 210 and the second short-circuit posts 230 may constitute the second layer 200 of the low-profile room antenna.

[0045] The third dielectric substrate 320 is provided with a metal floor 310, and the metal floor 310 can be bonded to the third dielectric substrate 320. The third dielectric substrate 320 is provided with a plurality of third shorting posts 330 distributed in a semicircular pattern, and the third shorting posts 330 can be evenly distributed in a semicircular pattern, and the sizes of the third shorting posts 330 are the same.

[0046] Each first short-circuit post 130, each second short-circuit post 230 and each third short-circuit post 330 corresponds to each other. The sizes of each first short-circuit post 130, each second short-circuit post 230 and each third short-circuit post 330 may be the same or different, and are not specifically limited here. In order to reduce the processing cost, the sizes of each first short-circuit post 130, each second short-circuit post 230 and each third short-circuit post 330 may be set to be the same, so that the resonant frequencies of the formed first resonant cavity and the second resonant cavity are consistent, forming a stable working frequency band. If the sizes of each first short-circuit post 130, each second short-circuit post 230 and each third short-circuit post 330 differ too much, it will affect the difficulty of adjusting the impedance matching.

[0047] A coupling slot 240 is formed on the second patch 210 , and a feeding through hole corresponding to the coupling slot 240 is formed on the third dielectric substrate 320 and the metal floor 310 , and a first feeding structure 360 ​​is disposed in the feeding through hole.

[0048] The third dielectric substrate 320 , the metal floor 310 , the first feeding structure 360 ​​, and the third short-circuit posts 330 may constitute the third layer 300 of the low-profile room antenna.

[0049] A second feeding structure 440 is disposed on the fourth dielectric substrate 420, and the second feeding structure 440 may be bonded to the fourth dielectric substrate 420. The first feeding structure 360 ​​is in contact with the second feeding structure 440, and the second feeding structure 440 is used to receive an input signal.

[0050] The fourth dielectric substrate 420 and the second feeding structure 440 may constitute a fourth layer 400 of the low-profile room antenna.

[0051] The first dielectric substrate 120, the second dielectric substrate 220, the third dielectric substrate 320, the fourth dielectric substrate 420 and the metal floor 310 may all be in the shape of a cuboid, the shapes of the first patch 110 and the second patch may be set as required, and the shapes of each first short-circuit post 130, each second short-circuit post 230 and each third short-circuit post 330 may all be in the shape of a hollow cylinder with a metallized inner wall.

[0052] The first patch 110 , the second patch 210 , and the metal ground 310 are all grounded.

[0053] Each first short-circuit post 130 can form a first resonant cavity between the first patch 110 and the second patch 210, each second short-circuit post 230 and each third short-circuit post 330 can form a second resonant cavity between the second patch 210 and the metal floor 310, and both the first resonant cavity and the second resonant cavity can be semi-enclosed and semi-open substrate integrated waveguide resonant cavities, and signals can be radiated through the open areas of the first resonant cavity and the second resonant cavity respectively, and quasi-omnidirectional radiation can be achieved by using the magnetic wall radiation characteristics of the substrate integrated waveguide. Therefore, the low-profile room antenna is a magnetic dipole antenna.

[0054] In the second resonant cavity, only signals that meet its resonance conditions exist, that is, through the second resonant cavity, frequency-selective filtering of the input signal can be achieved, and the first feeding structure 360 ​​can be used to couple the signal after frequency-selective filtering into the first resonant cavity through the second dielectric substrate 220 and the coupling slot 240. Through the first resonant cavity, an additional in-band pole can be provided for the low-profile room antenna.

[0055] The low-profile room-based antenna provided in an embodiment of the present invention includes: a first dielectric substrate, a second dielectric substrate, a third dielectric substrate and a fourth dielectric substrate connected in sequence, each of which has a compact structure to achieve a low-profile effect. Moreover, since the plurality of first short-circuit posts, the plurality of second short-circuit posts and the plurality of third short-circuit posts are distributed in a semicircular shape, the circularity of the radiated signal pattern can be improved. Due to the presence of the second resonant cavity, the function of frequency selective filtering is realized, so that the low-profile room-based antenna integrates the heterodyne decoupling capability. Compared with the existing quasi-omnidirectional antenna, the low-profile room-based antenna, in addition to realizing the out-of-band harmonic suppression function, also has the advantages of high performance, low profile and simple structure, realizing the integrated integration of antenna and filter and functional fusion.

[0056] Based on the above embodiments, Figure 1 As shown, the first feeding structure 360 ​​includes an in-hole feeding probe 350 and a feeding disk 340 connected to the in-hole feeding probe 350 .

[0057] The in-hole feeding probe 350 is disposed in the feeding through hole, contacts the second feeding structure 440 , and is not connected to the metal floor 310 .

[0058] The feeding disk 340 is located in the second resonant cavity and is spaced apart from the second patch 210 , so as to prevent the in-hole feeding probe 350 , the feeding disk 340 and the second feeding structure 440 from being grounded.

[0059] On the basis of the above embodiment, the centers of the in-hole feeding probe 350 and the feeding disc 340 are on the same axis, which reduces the possibility of the in-hole feeding probe 350 and the feeding disc 340 being grounded.

[0060] Based on the above embodiments, Figure 1 As shown, the second feeding structure 440 is a T-shaped feeding structure composed of multiple sections of high and low impedance lines, the feeding through hole includes a first feeding through hole and a second feeding through hole, and the first feeding structure is arranged in each feeding through hole. The coupling slot 240 includes a first coupling slot and a second coupling slot, and the first end of the vertical portion 410 of the T-shaped feeding structure, the first feeding through hole and the first coupling slot correspond to each other.

[0061] The vertical portion 410 of the T-shaped feeding structure is used to receive input signals, and the horizontal portion of the T-shaped feeding structure includes a first end and a second end for outputting two output signals. The first end and the second end of the horizontal portion of the T-shaped feeding structure are respectively provided with a first feeding probe 430 and a second feeding probe 431.

[0062] The first end of the horizontal portion of the T-shaped feeding structure, the first feeding through hole and the first coupling slot correspond one to one, and the first feeding probe 430 is electrically connected to the in-hole feeding probe in the first feeding through hole.

[0063] The second end of the horizontal portion of the T-shaped feeding structure, the second feeding through hole and the second coupling slot correspond one to one, and the second feeding probe 431 is electrically connected to the in-hole feeding probe in the second feeding through hole.

[0064] Through the T-shaped feeding structure, the input signal received by the vertical part 410 can be divided into two output signals with the same amplitude and consistent phase. The two output signals are fed synchronously, which can remove high-frequency stray signals in the output signals and achieve high-frequency harmonic suppression.

[0065] Based on the above embodiment, the position of the coupling slot on the second patch is based on the antenna pattern TM 21 and TM 02 Combined with the phase and amplitude information of the signal on the feeding disk 340, without affecting the fundamental mode TM 01 While working, some high-order harmonic modes can be suppressed.

[0066] Specifically, the position of the coupling slot 240 on the second patch 210 is based on the antenna pattern TM 21 and TM 02 The intersection points of the virtual electric walls are determined.

[0067] Based on the above embodiment, the first patch 110 and the second patch 210 are both semicircular in shape and have the same size, which can simplify the circuit board structure, reduce the manufacturing difficulty, and improve the strength and stability of the circuit board. In addition, the semicircular first patch 110 and the second patch 210 can also reduce the reflection and scattering of electromagnetic waves and improve the performance of the low-profile room antenna.

[0068] Based on the above embodiment, the coupling slot 240 is rectangular, and the angle between the long side of the coupling slot 240 and the straight side of the second patch 210 is 45°. The coupling slot 240 is arranged along the current direction when the fundamental modes of the two resonant cavities resonate. In this way, the influence of the coupling slot 240 on the radiation characteristics of the low-profile room antenna can be minimized.

[0069] On the basis of the above embodiment, the first patch 110 is connected to the first dielectric substrate 120 and the plurality of first short-circuit posts 130 by welding or conductive adhesive;

[0070] The second patch 210 is connected to the second dielectric substrate 220 and the plurality of second short-circuit posts 230 by welding or conductive adhesive.

[0071] The connection by welding or conductive adhesive can, on the one hand, reduce the impedance discontinuity at the connection and improve the radiation efficiency and gain of the antenna. On the other hand, the connection by welding and conductive adhesive is relatively firm and not easy to loosen or fall off.

[0072] On the basis of the above embodiment, the first dielectric substrate 120, the second dielectric substrate 220, the third dielectric substrate 320 and the fourth dielectric substrate 420 are connected by stacking or conductive adhesive, which can improve the stability of the low-profile room antenna.

[0073] On the basis of the above embodiment, the first dielectric substrate 120, the second dielectric substrate 220, the third dielectric substrate 320 and the fourth dielectric substrate 420 are all flame retardant copper clad laminates (FR-4). Among them, FR-4 has good mechanical strength, can withstand large external forces, and is not easy to deform. FR-4 also has good flame retardancy and high safety. In addition, the dielectric constant and loss factor of FR-4 are relatively stable, so that the attenuation and distortion of the signal during transmission can be relatively small, which can improve the transmission quality of the signal.

[0074] The first patch 110, the second patch 210 and the metal floor 310 are all copper plates or aluminum plates. Among them, the copper plate has good electrical conductivity, thermal conductivity and high mechanical strength, and can withstand large tension and pressure. The aluminum plate is light in weight, low in price, and has a smooth surface, which can reduce the reflection and scattering of electromagnetic waves and improve the gain and directivity of the antenna.

[0075] Figure 2 A schematic diagram of scattering parameters and actual gain of a low-profile indoor antenna provided by an embodiment of the present invention, from Figure 2 It can be seen that the central operating frequency of the low-profile indoor antenna At 2.105GHz, the simulated reflection coefficient of antenna IV is S 11 The two in-band poles in the curve are located at 2.10 GHz and 2.11 GHz respectively, and the reflection coefficient S 11 The frequency coverage range of <-10dB is 2.09GHz-2.12GHz, and the gain of the antenna in the maximum radiation direction within the working frequency band remains stable, about 2.4dBi. In addition, the low-profile indoor antenna also suppresses a series of high-order modes so that the operating frequency of the high-order modes appears outside 6.5GHz, forming a wide stopband performance with a stopband frequency range of the working frequency. 3.09 times of that of the low-profile indoor antenna. ( is the free space wavelength at the center frequency), the profile is low.

[0076] Figure 3 A schematic diagram of the radiation direction of a low-profile indoor antenna provided in an embodiment of the present invention. Figure 3 The E-plane ( yoz ) and H surface ( xoy ). Figure 3 It can be seen that the maximum radiation direction of the E-plane pattern at the two resonant frequencies is approximately: , azimuth In the direction of maximum radiation, the E-plane pattern presents a quasi-circular shape as a whole, and the cross-polarization is less than -20dB. Therefore, it is shown that the radiation pattern of the low-profile indoor antenna has good stability within the operating frequency range and has good omnidirectional radiation characteristics.

[0077] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, and of course, can also be implemented by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the relevant technology can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiment.

[0078] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A low-profile indoor antenna, characterized in that: include: A first dielectric substrate, a second dielectric substrate, a third dielectric substrate and a fourth dielectric substrate connected in sequence; A first patch is arranged on the first dielectric substrate, and a plurality of first short-circuit posts distributed in a semicircular shape are arranged in the first dielectric substrate; A second patch is arranged on the second dielectric substrate, and a plurality of second short-circuit posts distributed in a semicircular pattern are arranged in the second dielectric substrate; the plurality of first short-circuit posts and the plurality of second short-circuit posts are respectively located on two sides of the second patch; A metal floor is arranged on the third dielectric substrate, a plurality of third short-circuit posts distributed in a semicircular shape are arranged in the third dielectric substrate, and the plurality of second short-circuit posts and the plurality of third short-circuit posts are both located between the second patch and the metal floor; The plurality of first short-circuit posts, the plurality of second short-circuit posts and the plurality of third short-circuit posts correspond to each other one by one; A coupling gap is formed on the second patch, a feeding through hole corresponding to the coupling gap is formed on the third dielectric substrate and the metal floor, and a first feeding structure is arranged in the feeding through hole; A second feeding structure is disposed on the fourth dielectric substrate, the first feeding structure is in contact with the second feeding structure, and the second feeding structure is used to receive an input signal; A first resonant cavity is formed between the first patch and the second patch, and a second resonant cavity is formed between the second patch and the metal floor. The first resonant cavity and the second resonant cavity are used to radiate signals.

2. The low-profile room antenna according to claim 1, characterized in that: The first feeding structure comprises an in-hole feeding probe and a feeding disk connected to the in-hole feeding probe; The in-hole feeding probe is disposed in the feeding through hole and contacts the second feeding structure; The feeding disk is located in the second resonant cavity.

3. The low-profile room antenna according to claim 2, characterized in that: The center of the in-hole feeding probe and the center of the feeding disk are on the same axis.

4. The low-profile room antenna according to claim 1, characterized in that: The second feeding structure is a T-shaped feeding structure composed of multiple sections of high and low impedance lines, the feeding through hole includes a first feeding through hole and a second feeding through hole, and the coupling slot includes a first coupling slot and a second coupling slot; The vertical portion of the T-shaped feeding structure is used to receive the input signal; The horizontal portion of the T-shaped feeding structure is used to output two output signals, and the first end and the second end of the horizontal portion of the T-shaped feeding structure are respectively provided with a first feeding probe and a second feeding probe; The first end of the horizontal portion of the T-shaped feeding structure, the first feeding through hole and the first coupling slot correspond to each other one by one, and the first feeding probe is electrically connected to the in-hole feeding probe in the first feeding through hole; The second end of the horizontal portion of the T-shaped feeding structure, the second feeding through hole and the second coupling slot correspond one to one, and the second feeding probe is electrically connected to the in-hole feeding probe in the second feeding through hole.

5. The low-profile room antenna according to claim 1, characterized in that: The location of the coupling slot on the second patch is based on the antenna pattern TM 21 and TM 02 The intersection points of the virtual electric walls are determined.

6. The low-profile room antenna according to claim 1, characterized in that: The first patch and the second patch are both semicircular in shape and have the same size.

7. The low-profile room antenna according to claim 6, characterized in that: The coupling slot is rectangular, and the angle between the long side of the coupling slot and the straight side of the second patch is 45°.

8. The low-profile room-space antenna according to any one of claims 1 to 7, characterized in that: The first patch is connected to the first dielectric substrate and the plurality of first short-circuit posts by welding or conductive glue; The second patch is connected to the second dielectric substrate and the plurality of second short-circuit posts by welding or conductive adhesive.

9. The low-profile room-space antenna according to any one of claims 1 to 7, characterized in that: The first dielectric substrate, the second dielectric substrate, the third dielectric substrate and the fourth dielectric substrate are connected by stacking or conductive adhesive.

10. The low-profile room-space antenna according to any one of claims 1 to 7, characterized in that: The first dielectric substrate, the second dielectric substrate, the third dielectric substrate and the fourth dielectric substrate are all flame-retardant copper-clad laminates; The first patch, the second patch and the metal floor are all copper plates or aluminum plates.

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