Miniaturized slot-coupled microstrip filter antenna

Abstract

The application discloses a miniaturized slot-coupled feed microstrip filter antenna, which comprises, from bottom to top, a lower dielectric plate, a metal ground plate, an upper dielectric plate, a feed network located on the lower surface of the lower dielectric plate and a radiation network located on the upper surface of the upper dielectric plate; the radiation network is an axisymmetric structure, which comprises a main patch, two slave patches and two Z-shaped microstrip branches; the metal ground plate is provided with a strip-shaped ground plate coupling gap; the strip-shaped ground plate coupling gap is located directly below the main patch; the feed network comprises a main feed line and an open circuit branch. The feed network excites the upper radiation network through the strip-shaped ground plate coupling gap on the ground plate. By adjusting the length of the open circuit branch and the length of the Z-shaped microstrip branch, good three-order resonant response can be obtained, and high roll-off radiation zero points are formed on both sides of the passband.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of antennas, in particular to a miniaturized slot-coupled feed microstrip filter antenna. BACKGROUND

[0002] In recent years, the rapid development of 5G communication systems has led to an increasing demand for small, high-transmission-efficiency devices, highlighting the importance of continuous research and development in the field of microwave front-end devices, especially antenna technology. The traditional method of designing filters and antennas separately introduces additional losses into the system and is not conducive to the miniaturization of the system. To meet the needs of the times, filter antennas have emerged as the best choice due to their efficient integrated design of antennas and filters, and have gradually attracted widespread research attention.

[0003] The most intuitive way to implement a filter antenna is to directly connect the antenna radiator and the filter structure, but this will result in an increase in size, an increase in profile, and a decrease in antenna gain. Today, integrated design has become the mainstream trend in filter antennas. Under the guidance of this method, filter antennas are developing towards miniaturization, and do not require obvious filter circuits.

[0004] Parasitic elements can effectively suppress unwanted frequency bands without introducing additional losses, so they have received widespread attention in the trend towards miniaturization. Parasitic elements can be used in various types of antennas to achieve filter responses, among which patch antennas show the greatest potential in achieving compact sizes. Common parasitic structures include U-shaped resonators, parasitic branches, shorted posts, slots, and stacked patches. However, these elements can easily result in a large size, especially branches and stacked patches.

[0005] Filter branches are usually added to the feed line to absorb unwanted signals. However, due to the parallel structure of the branches, the size of the feed line structure will inevitably increase. Using stacked patches is also an effective method to achieve filtering, but there are problems of high profile and design complexity. Therefore, it is still a great challenge to design a filter antenna with good radiation performance while maintaining a compressed size. SUMMARY

[0006] The purpose of the present application is to address the shortcomings of existing filter microstrip antenna designs, which are complex and large in size, and to provide a miniaturized slot-coupled feed microstrip filter antenna.

[0007] The purpose of the present application can be achieved by adopting the following technical solutions:

[0008] A miniaturized slot-coupled feed microstrip filter antenna, comprising, from bottom to top, a lower dielectric plate, a metal ground plate, an upper dielectric plate, and a feed network located on the lower surface of the lower dielectric plate, and a radiation network located on the upper surface of the upper dielectric plate.

[0009] The radiation network is an axisymmetric structure, which comprises one main patch, two sub-patches and two Z-shaped microstrip branches; the two sides of the main patch are connected with one sub-patch through one Z-shaped microstrip branch respectively.

[0010] The metal floor is provided with a strip-shaped floor coupling gap; the strip-shaped floor coupling gap is located directly below the main patch.

[0011] The feeding network comprises a main feeder and an open circuit branch; one end of the main feeder is connected with one end of the open circuit branch.

[0012] The projection of the main feeder and the strip-shaped floor coupling gap on the feeding network is arranged vertically.

[0013] The open circuit branch and the projection of the strip-shaped floor coupling gap on the feeding network are arranged staggeredly.

[0014] The total length of the main feeder is equal to one quarter of the wavelength of the low-frequency radiation zero point.

[0015] The open circuit branch is in a Z-shaped structure.

[0016] The length of the sub-patch is greater than that of the main patch, and the width of the sub-patch is smaller than that of the main patch.

[0017] The Z-shaped microstrip branch connects the upper half of the non-radiation edge of the main patch and the lower half of the non-radiation edge of the sub-patch.

[0018] By adjusting the length and width of the Z-shaped microstrip branch, the third resonance and the high-frequency zero point of the antenna can be adjusted, and the impedance matching can be further improved.

[0019] By adjusting the length of the open circuit branch, the positions of the low-frequency zero point and the first resonance can be adjusted.

[0020] The TM mode of the main patch corresponds to the second resonance. 10

[0021] Compared with the prior art, the present application has the following advantages and beneficial effects:

[0022] 1. The slot-coupled feeding microstrip filter antenna has a wide passband (14.2%) and a flat gain curve in the passband range, with a maximum gain of 6.34 dBi and a minimum gain of 5.72 dBi.

[0023] 2. The slot-coupled feeding microstrip filter antenna has high roll-off on both sides of the passband, with a low / high frequency roll-off slope of 500 / 366.6 dB / GHz.

[0024] 3. The slot-coupled feeding microstrip filter antenna has independent adjustable zero points, a relatively simple structure and a convenient design process. ​

[0025] 4. The slot-coupled microstrip filter antenna of the present application has small size, low profile, low cost and good application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 A 3D structure diagram of the microstrip filter antenna provided for the embodiment of the present application.

[0027] Figure 2 A side view of the microstrip filter antenna provided for the embodiment of the present application.

[0028] Figure 3 A top view of the microstrip filter antenna provided for the embodiment of the present application.

[0029] Figure 4 A bottom view of the microstrip filter antenna provided for the embodiment of the present application.

[0030] Figure 5 A simulation result curve diagram of the microstrip filter antenna provided for the embodiment of the present application and the gain (Realized Gain) parameter, the solid line is the gain simulation curve, and the dotted line is the simulation curve.

[0031] Figure 6 Radiation patterns of the microstrip filter antenna provided for the embodiment of the present application at 2.36 GHz; wherein (a) is the XOZ plane, and (b) is the YOZ plane.

[0032] Figure 7 Radiation patterns of the microstrip filter antenna provided for the embodiment of the present application at 2.53 GHz; wherein (a) is the XOZ plane, and (b) is the YOZ plane.

[0033] Figure 8 Radiation patterns of the microstrip filter antenna provided for the embodiment of the present application at 2.69 GHz; wherein (a) is the XOZ plane, and (b) is the YOZ plane.

[0034] Markings in the figure: 1, lower dielectric plate; 2, upper dielectric plate; 3, main feed line; 4, open stub; 5, ground plate coupling slot; 6, main patch; 7, slave patch; 8, Z-shaped microstrip stub. DETAILED DESCRIPTION

[0035] The present application will be further described below in combination with specific implementation examples.

[0036] As Figures 1 to 4 ​As shown, this embodiment provides a miniaturized slot-coupled fed microstrip filter antenna with a center frequency of 2.53 GHz and gain zeros at 2.28 GHz and 2.80 GHz, respectively. It includes a lower dielectric substrate 1, a metal ground plane, and an upper dielectric substrate 2 arranged sequentially from bottom to top, as well as a feed network located on the lower surface of the lower dielectric substrate 1 and a radiating network located on the upper surface of the upper dielectric substrate 2. This structure of placing the radiating network and the feed network in layers helps to achieve miniaturization of the filter antenna.

[0037] The radiating network is an axisymmetric structure with left-right symmetry, comprising a main patch 6, two slave patches 7, and two Z-shaped microstrip stubs 8. Each side of the main patch 6 is connected to a slave patch 7 via a Z-shaped microstrip stub 8. The Z-shaped microstrip stub 8 connects the upper half of the non-radiating edge of the main patch 6 and the lower half of the non-radiating edge of the slave patch 7. The loading of the Z-shaped microstrip stub 8 reduces the coupling between the main patch 6 and the slave patches 7, improves the impedance matching of the passband, and significantly compresses the lateral dimensions of the antenna. Furthermore, loading the Z-shaped microstrip stub 8 lengthens the radiated current path, resulting in a lower frequency passband and higher bandwidth compared to the case without the Z-shaped microstrip stub 8. The TM10 mode of the main patch 6 corresponds to the second resonance, while the loading of the slave patches 7 introduces the third resonance. By adjusting the length of the Z-shaped microstrip stub 8 or the slave patch 7, the antenna's third resonance and high-frequency null point can be adjusted, further improving impedance matching.

[0038] The length of patch 7 is slightly larger than that of main patch 6, specifically by about 1mm, but the width is narrower, specifically by about 3mm.

[0039] The metal floor has a strip-shaped floor coupling gap 5; the strip-shaped floor coupling gap 5 is located directly below the width axis of the main patch 6, and its length does not exceed the width of the main patch 6.

[0040] The power supply network includes a main feed line 3 and an open stub 4; the part of the main feed line 3 that extends beyond the strip floor coupling gap 5 is connected in parallel with the open stub 4, and its total length is approximately equal to one-quarter wavelength of the low-frequency radiation null point. The open stub 4 has a Z-shaped structure, which makes the structure more compact; by adjusting the length of the open stub 4, the position of the low-frequency null point and the first resonance can be adjusted.

[0041] The coupling gap 5 between the main feeder 3 and the strip floor falls vertically on the projection of the feeder network.

[0042] The projections of the open branch 4 and the strip floor coupling gap 5 on the feed network are staggered.

[0043] The signal is fed in through the main feed line 3, and the energy is coupled to the upper radiation network through the floor coupling gap 5 of the metal ground plane. By adjusting the length of the open stub 4, the length of the Z-shaped microstrip stub 8, and the length from the patch 7, a good third-order resonant response can be obtained, and high roll-off radiation nulls are formed at both edges of the passband.

[0044] In this embodiment, both the lower dielectric substrate 1 and the upper dielectric substrate 2 are made of "Rogers RO4003", with a dielectric constant of 3.55 and a loss tangent of 0.0027. The thickness of dielectric substrate 1 is 0.5 mm and the thickness of dielectric substrate 2 is 3 mm.

[0045] After adjusting the dimensional parameters of each part of the slot-coupled fed microstrip filter antenna in this embodiment, the slot-coupled fed microstrip filter antenna of this embodiment was verified and simulated through calculation and electromagnetic field simulation. Figure 5 As shown, the performance of this antenna in the frequency range of 2GHz to 3.2GHz is given. The graph shows the simulation results for the input port return loss and the realized gain parameter. There are two curves in the graph, the dashed line being... The solid line represents the gain. It can be seen that in the 2.35GHz~2.71GHz frequency band, the value of the dashed curve is less than -10dB, and the value of the solid line is around 6dBi. The simulation results show that the slot-coupled fed microstrip filter antenna of this embodiment has a wide passband and stable gain, which can meet the requirements of wireless communication system applications such as Wi-Fi in the 2.35GHz~2.71GHz frequency band.

[0046] The radiation patterns of the slot-coupled fed microstrip filter antenna HFSS simulation model at 2.36 GHz in the XOZ and YOZ planes are as follows. Figure 6 (a) Figure 6 As shown in (b).

[0047] The radiation patterns of the slot-coupled fed microstrip filter antenna HFSS simulation model at 2.53 GHz in the XOZ and YOZ planes are as follows. Figure 7 (a) Figure 7 As shown in (b).

[0048] The radiation patterns of the slot-coupled fed microstrip filter antenna HFSS simulation model at 2.69 GHz in the XOZ and YOZ planes are as follows. Figure 8 (a) Figure 8 As shown in (b).

[0049] In the above embodiment, the lower dielectric plates 1 and 2 are made of any one of TACONIC TLX, polyimide, polytetrafluoroethylene glass cloth and co-fired ceramic, and the metal of the upper dielectric plate metal floor 3, the main feeder 4, the open stub 5, the main patch 6, the slave patch 7 and the Z-shaped microstrip stub 8 is any one of aluminum, iron, tin, copper, silver, gold and platinum, or an alloy of any one of aluminum, iron, tin, copper, silver, gold and platinum.

[0050] The above description is the preferred embodiment of the present application, it should be pointed out that for those skilled in the art, without departing from the principles of the present application, can make a number of improvements and refinements, these improvements and refinements are also considered to be within the scope of the present application.

Claims

1. A miniaturized slot-coupled microstrip filtered antenna, characterized in that The antenna comprises a lower dielectric plate (1), a metal ground plate, an upper dielectric plate (2) arranged in sequence from bottom to top, a feed network on the lower surface of the lower dielectric plate (1), and a radiation network on the upper surface of the upper dielectric plate (2); The radiation network is an axisymmetric structure comprising a main patch (6), two slave patches (7), and two Z-shaped microstrip stubs; the two sides of the main patch (6) are connected to a slave patch (7) through a Z-shaped microstrip stub respectively; The metal ground plate is provided with a strip-shaped ground plate coupling gap (5); The strip-shaped ground plate coupling gap (5) is located directly below the main patch (6); The feed network comprises a main feed line (3) and an open stub (4); one end of the main feed line (3) is connected to one end of the open stub (4); The projection of the main feed line (3) and the strip-shaped ground plate coupling gap (5) on the feed network is arranged vertically; The open stub (4) and the projection of the strip-shaped ground plate coupling gap (5) on the feed network are arranged staggered.

2. The miniaturized slot-coupled microstrip filtered antenna according to claim 1, characterized in that, The total length of the main feed line (3) is equal to one quarter of the wavelength of the low-frequency radiation zero point.

3. The miniaturized slot-coupled fed microstrip waveguide filter antenna according to claim 1, characterized in that The open stub (4) is in Z-shaped structure.

4. The miniaturized slot-coupled fed microstrip waveguide filter antenna according to claim 1, characterized in that The length of the slave patch (7) is greater than that of the main patch (6), and the width of the slave patch (7) is smaller than that of the main patch (6).

5. The miniaturized slot-coupled fed microstrip waveguide filter antenna according to claim 1, characterized in that The Z-shaped microstrip stub connects the upper half of the non-radiation edge of the main patch (6) and the lower half of the non-radiation edge of the slave patch (7).

6. The miniaturized slot-coupled fed microstrip waveguide filter antenna of claim 1, wherein By adjusting the length and width of the Z-shaped microstrip stub, the third resonance and high-frequency zero point of the antenna are adjusted, and the impedance matching is further improved.

7. The miniaturized slot-coupled fed microstrip waveguide filter antenna according to claim 1, characterized in that By adjusting the length of the open stub (4), the positions of the low-frequency zero point and the first resonance are adjusted.

8. The miniaturized slot-coupled fed microstrip waveguide filter antenna according to claim 1, characterized in that The TM10 mode of the main patch (6) corresponds to the second resonance.

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