Miniaturized slot coupling feed microstrip filtering antenna

Abstract

The antenna comprises a lower dielectric plate, a metal floor, 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 which are sequentially arranged from bottom to top. The radiation network is of an axisymmetric structure and comprises a main patch, two slave patches and two Z-shaped microstrip branches; the metal floor is provided with a strip-shaped floor coupling gap. The strip-shaped floor coupling slot is positioned right below the main patch; the feed network comprises a main feed line and an open-circuit branch. And the feed network excites the upper-layer radiation network through the strip-shaped floor coupling gap on the floor. Good third-order resonance response can be obtained by adjusting the length of the open circuit branch knot and the length of the Z-shaped microstrip branch knot, and high roll-off radiation zero points are formed at the edges of the two sides of the passband.

Description

Technical Field

[0001] The present invention relates to the field of antenna technology, and in particular to a miniaturized slot-coupled feeding microstrip filtering antenna. Background Art

[0002] In recent years, 5G communication systems have developed rapidly, and the demand for miniaturized and high-transmission efficiency devices has been growing. This highlights 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 will introduce additional losses to the system and is not conducive to the miniaturization of the system. In order to meet the needs of the development of the times, filter antennas have stood out with 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 results in an increase in size, a higher profile, and a decrease in antenna gain. Today, fusion design has become the mainstream trend for filter antennas. Under the guidance of this method, filter antennas are moving towards miniaturization without the need for 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 of miniaturization. Parasitic elements can be used in a variety of antenna types to achieve filtering responses, among which patch antennas show the greatest potential in achieving compact size. Commonly used parasitic structures include U-shaped resonators, parasitic stubs, shorting posts, slots, and stacked patches. However, these elements can easily lead to large sizes, especially stubs 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 way to achieve filtering, but there are problems with high profile and design complexity. Therefore, designing a filter antenna with good radiation performance while maintaining a compressed size remains a major challenge. Summary of the invention

[0006] The purpose of the present invention is to provide a miniaturized slot-coupled feeding microstrip filtering antenna in view of the shortcomings of the existing filtering microstrip antenna, which is complex in design and large in size.

[0007] The purpose of the present invention can be achieved by adopting the following technical solutions: A miniaturized slot-coupled fed microstrip filtering antenna comprises a lower dielectric plate, a metal floor, an upper dielectric plate, and a feeding 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 includes a main patch, two slave patches, and two Z-shaped microstrip branches; the two sides of the main patch are connected to a slave patch through a Z-shaped microstrip branch respectively; The metal floor is provided with a strip floor coupling gap; the strip floor coupling gap is located directly below the main patch; The feed network includes a main feeder and an open-circuit branch; one end of the main feeder is connected to one end of the open-circuit branch; The projection of the main feeder line and the strip floor coupling gap on the feeder network is arranged vertically; The projections of the open-circuit branches and the strip floor coupling gaps on the feeder network are staggered; The total length of the main feed line is equal to one quarter of the wavelength of the low-frequency radiation zero point; The open branch is a Z-shaped structure; The slave patch is longer than the master patch and smaller in width than the master patch; The Z-shaped microstrip branch connects the upper half of the non-radiating edge of the main patch and the lower half of the non-radiating edge of the slave patch; By adjusting the length and width of the Z-type microstrip branch, the third resonance and high-frequency zero point of the antenna can be adjusted, and the impedance matching can be further improved.

[0008] By adjusting the length of the open-circuit branch, the position of the low-frequency zero point and the first resonance can be adjusted.

[0009] Main patch TM 10 mode corresponds to the second resonance.

[0010] Compared with the prior art, the present invention has the following advantages and beneficial effects: 1. The slot-coupled fed microstrip filter antenna of the present invention has a relatively wide passband (14.2%) and a flat gain curve within the passband range, with the maximum gain and the minimum gain being 6.34 dBi and 5.72 dBi respectively.

[0011] 2. The slot-coupled fed microstrip filter antenna of the present invention has a very high roll-off property at both edges of the passband, and the low / high frequency roll-off slope reaches 500 / 366.6 dB / GHz.

[0012] 3. The slot-coupled fed microstrip filter antenna of the present invention has an independently adjustable zero point, a relatively simple structure and a convenient design process.

[0013] 4. The slot-coupled fed microstrip filter antenna of the present invention has small size, low profile, low cost and good application prospect. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 A 3D structural diagram of a microstrip filter antenna provided in an embodiment of the present invention.

[0015] Figure 2 A side view of a microstrip filter antenna provided in an embodiment of the present invention.

[0016] Figure 3 A top view of a microstrip filter antenna provided in an embodiment of the present invention.

[0017] Figure 4 A bottom view of the microstrip filter antenna provided in an embodiment of the present invention.

[0018] Figure 5 The microstrip filter antenna provided by the embodiment of the present invention The simulation result curve of the gain (Realized Gain) parameter, the solid line is the gain simulation curve, and the dotted line is Simulation curve.

[0019] Figure 6 The radiation pattern of the microstrip filter antenna provided in an embodiment of the present invention at 2.36 GHz; (a) is the XOZ plane, and (b) is the YOZ plane.

[0020] Figure 7 The radiation pattern of the microstrip filter antenna provided in an embodiment of the present invention at 2.53 GHz; (a) is the XOZ plane, and (b) is the YOZ plane.

[0021] Figure 8 The radiation pattern of the microstrip filter antenna provided in an embodiment of the present invention at 2.69 GHz; (a) is the XOZ plane, and (b) is the YOZ plane.

[0022] Markings in the figure: 1. Lower dielectric plate; 2. Upper dielectric plate; 3. Main feed line; 4. Open-circuit branch; 5. Floor coupling gap; 6. Main patch; 7. Slave patch; 8. Z-type microstrip branch. DETAILED DESCRIPTION

[0023] The present invention will be further described below in conjunction with specific implementation examples.

[0024] like Figures 1 to 4 As shown, a miniaturized slot-coupled fed microstrip filter antenna provided in this embodiment has a center frequency of 2.53 GHz, and the positions of the gain zero points are 2.28 GHz and 2.80 GHz respectively. The antenna includes a lower dielectric plate 1, a metal floor, an upper dielectric plate 2, which are arranged from bottom to top, and a feeding network located on the lower surface of the lower dielectric plate 1, and a radiation network located on the upper surface of the upper dielectric plate 2. The structure of placing the radiation network and the feeding network in layers helps to miniaturize the filter antenna.

[0025] The radiation network is an axisymmetric structure with bilateral symmetry, which includes a main patch 6, two slave patches 7, and two Z-shaped microstrip branches 8; the two sides of the main patch 6 are connected to a slave patch 7 through a Z-shaped microstrip branch 8; the Z-shaped microstrip branch 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 branch 8 reduces the coupling between the main patch 6 and the slave patch 7, improves the impedance matching of the passband, and significantly compresses the lateral size of the antenna. In addition, loading the Z-shaped microstrip branch 8 lengthens the length of the radiation current path, and has a lower frequency passband and a higher bandwidth compared to the case where the Z-shaped microstrip branch 8 is not loaded. Among them, the TM10 mode of the main patch 6 corresponds to the second resonance, and the loading of the slave patch 7 introduces the third resonance. By adjusting the length of the Z-shaped microstrip branch 8 or the length of the slave patch 7, the third resonance and high-frequency zero point of the antenna can be adjusted, and the impedance matching can be further improved.

[0026] The length of the secondary patch 7 is slightly greater than that of the primary patch 6, specifically, it may be slightly greater by 1 mm, but the width is narrower, specifically, it is slightly smaller by 3 mm.

[0027] The metal floor is provided with a strip floor coupling gap 5 ; the strip 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 .

[0028] The feeding network includes a main feeder line 3 and an open-circuit branch 4; the portion of the main feeder line 3 that exceeds the strip floor coupling gap 5 is connected in parallel with the open-circuit branch 4, and its total length is approximately equal to one-quarter wavelength of the low-frequency radiation zero point. The open-circuit branch 4 is a Z-shaped structure, making the structure more compact; by adjusting the length of the open-circuit branch 4, the position of the low-frequency zero point and the first resonance can be adjusted.

[0029] The main feeder line 3 and the projection of the strip floor coupling slot 5 on the feeder network are arranged perpendicularly.

[0030] The projections of the open-circuit branches 4 and the strip floor coupling gaps 5 on the feeder network are staggered.

[0031] 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 floor. By adjusting the length of the open-circuit branch 4, the length of the Z-type microstrip branch 8, and the length of the follower patch 7, a good third-order resonance response can be obtained, and a high roll-off radiation zero point can be formed at the edges of both sides of the passband.

[0032] In the design of this embodiment, the material of the lower dielectric plate 1 and the upper dielectric plate 2 are both "Rogers RO4003", with a dielectric constant of 3.55 and a loss tangent of 0.0027. The thickness of the dielectric plate 1 is 0.5 mm, and the thickness of the dielectric plate 2 is 3 mm.

[0033] After adjusting the size parameters of each part of the slot-coupled fed microstrip filter antenna of this embodiment, the slot-coupled fed microstrip filter antenna of this embodiment is verified and simulated by calculation and electromagnetic field simulation. Figure 5 As shown, the antenna is given in the frequency range of 2GHz~3.2GHz (Input port return loss) and realized gain (Realized Gain) parameter simulation results curve, there are two curves in the figure, the dotted line is , the solid line is the gain; it can be seen that within the frequency band of 2.35GHz~2.71GHz, the value of the dotted line curve is less than -10dB, and the solid line value is around 6dBi. The simulation results show that the slot-coupled fed microstrip filter antenna of this embodiment has a wider passband and stable gain, and can meet the requirements of wireless communication system applications such as Wi-Fi in the frequency band of 2.35GHz~2.71GHz.

[0034] The radiation patterns of the slot-coupled-fed microstrip filter antenna HFSS simulation model of this embodiment at 2.36 GHz on the XOZ and YOZ planes are as follows: Figure 6 Middle (a), Figure 6 As shown in (b).

[0035] The radiation patterns of the slot-coupled-fed microstrip filter antenna HFSS simulation model of this embodiment at 2.53 GHz on the XOZ and YOZ planes are as follows: Figure 7 Middle (a), Figure 7 As shown in (b).

[0036] The radiation patterns of the slot-coupled-fed microstrip filter antenna HFSS simulation model of this embodiment at 2.69 GHz on the XOZ and YOZ planes are as follows: Figure 8 Middle (a), Figure 8 As shown in (b).

[0037] 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 floor 3 of the upper dielectric plate, the main feed line 4, the open branch 5, the main patch 6, the slave patch 7 and the Z-type microstrip branch 8 are made of 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.

[0038] The above is a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the principle of the present invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A miniaturized slot-coupled fed microstrip filter antenna, characterized in that It comprises a lower dielectric plate (1), a metal floor, an upper dielectric plate (2) which are arranged in sequence from bottom to top, a feeding network located on the lower surface of the lower dielectric plate (1), and a radiation network located 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 branches; both sides of the main patch (6) are connected to a slave patch (7) via a Z-shaped microstrip branch respectively; The metal floor is provided with a strip-shaped floor coupling gap (5); The strip floor coupling gap (5) is located directly below the main patch (6); The feed network comprises a main feeder line (3) and an open-circuit branch node (4); one end of the main feeder line (3) is connected to one end of the open-circuit branch node (4); The projection of the main feeder line (3) and the strip floor coupling gap (5) on the feeder network is arranged vertically; The projections of the open-circuit branches (4) and the strip floor coupling gaps (5) falling on the feeder network are staggered.

2. A miniaturized filtering microstrip 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. A miniaturized filtering microstrip antenna according to claim 1, characterized in that: The open-circuit branch (4) is a Z-shaped structure.

4. A miniaturized filtering microstrip antenna according to claim 1, characterized in that: The slave patch (7) is longer than the master patch (6) and smaller in width than the master patch (6).

5. A miniaturized filtering microstrip antenna according to claim 1, characterized in that: The Z-shaped microstrip branch 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).

6. A miniaturized filtering microstrip antenna according to claim 1, characterized in that: By adjusting the length and width of the Z-type microstrip branch, the third resonance and high-frequency zero point of the antenna can be adjusted, and the impedance matching can be further improved.

7. A miniaturized filtering microstrip antenna according to claim 1, characterized in that: The length of the open-circuit branch (4) is adjusted to adjust the position of the low-frequency zero point and the first resonance.

8. A miniaturized filtering microstrip 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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