A new type of multi-frequency broadband microstrip antenna

Abstract

The present invention discloses a novel multi-frequency broadband microstrip antenna, belonging to the field of antenna technology. Its coplanar waveguide structure and microstrip transmission line are placed on the upper surface of a dielectric substrate, the length of the coplanar waveguide structure is less than the microstrip transmission line, the coplanar waveguide structure includes a first coplanar waveguide ground plane and a second coplanar waveguide ground plane of the same size, the first coplanar waveguide ground plane and the second coplanar waveguide ground plane are symmetrically placed on both sides of the microstrip transmission line, and there is a gap between the first coplanar waveguide ground plane and the second coplanar waveguide ground plane and the microstrip transmission line; the ground plane is placed on the lower surface of the dielectric substrate, directly below one end of the microstrip transmission line. The present invention can achieve the effect of broadband multi-frequency, the designed frequency band can cover the wireless local area network and the global access microwave interconnection access frequency band, and realize the operation in multiple frequency bands at the same time, and also has the advantages of simple structure, reasonable design, and easy manufacturing.

Description

Technical Field

[0001] The invention belongs to the technical field of antennas, and in particular relates to a novel multi-frequency broadband microstrip antenna. Background Art

[0002] Communication system is a general term for technical systems used to complete the information transmission process. Modern communication systems are mainly realized by the propagation of electromagnetic waves in free space (wireless communication) or the transmission mechanism in guided media. In wireless communication systems, antennas occupy an important position. The essence of antennas is to complete the radiation and reception of electromagnetic energy through the mutual conversion of electric and magnetic fields under the basic principle of electromagnetic fields. In addition to the long-established wireless communication technology, the underlying principle of cutting-edge technologies such as mobile payment and wireless charging in recent years is still to use the electromagnetic induction phenomenon to achieve the mutual conversion of energy, so the application field of antennas is constantly expanding.

[0003] As far as antennas are concerned, reducing their size has become part of the research and improvement of communication equipment. However, blindly reducing the size of the antenna will affect its standing wave, gain, bandwidth and other index characteristics. Therefore, before designing, the transmission line method, cavity mode theory method, Green's function method, integral equation method and moment method are usually used to analyze the antenna characteristics. Microstrip antennas have been widely studied and applied due to their advantages such as light weight, small size, low profile, easy conformality and low cost. However, ordinary microstrip patch antennas are limited by the defects of narrow bandwidth, high loss and single structure and have not been widely used. Therefore, it is of great significance to carry out work to expand the working frequency band of microstrip antennas.

[0004] Microstrip antennas also have a fixed multi-frequency characteristic, that is, the same microstrip antenna can operate at multiple discrete frequency operating points to meet the needs of multiple communication frequency bands. Since the bandwidth of microstrip antennas is relatively narrow, the accuracy of the operating frequency point is required to be more precise. Any interference from the external environment will cause the frequency point of the microstrip antenna to drift, making the antenna unable to work normally. At present, domestic and foreign research has found that the bandwidth of microstrip antennas can be effectively broadened by reducing the equivalent resonant circuit, adding parasitic patches, using LC resonant circuits, loading short-circuit probes, and adding impedance matching networks. However, the above methods of increasing bandwidth will also affect the gain of the antenna, and both cannot be taken into account. Summary of the invention

[0005] In view of the above problems existing in the prior art, the object of the present invention is to provide a novel multi-frequency broadband microstrip antenna, which broadens the bandwidth near the center frequency of the microstrip antenna and has a multi-frequency effect.

[0006] To solve the above problems, the present invention adopts the following technical solutions.

[0007] A novel multi-frequency broadband microstrip antenna comprises a dielectric substrate, a coplanar waveguide structure, a microstrip transmission line and a ground plate;

[0008] The coplanar waveguide structure and the microstrip transmission line are placed on the upper surface of the dielectric substrate, the length of the coplanar waveguide structure is shorter than the microstrip transmission line, the coplanar waveguide structure comprises a first coplanar waveguide ground plane and a second coplanar waveguide ground plane of the same size, the first coplanar waveguide ground plane and the second coplanar waveguide ground plane are symmetrically placed on both sides of the microstrip transmission line, and gaps are left between the first coplanar waveguide ground plane and the second coplanar waveguide ground plane and the microstrip transmission line;

[0009] The grounding plate is placed on the lower surface of the dielectric substrate, and the grounding plate is located directly below one end of the microstrip transmission line.

[0010] The ground plate is semicircular, and the center of the circle is located just below one end of the microstrip transmission line.

[0011] A first parasitic patch is also provided on the upper surface of the dielectric substrate. The first parasitic patch is arranged at an end of the second coplanar waveguide ground plane away from the ground plane and close to the microstrip transmission line.

[0012] The first parasitic patch is rectangular.

[0013] The lower surface of the dielectric substrate is also provided with a second parasitic patch and a third parasitic patch of the same size. The second parasitic patch and the third parasitic patch are symmetrically placed on both sides directly below the microstrip transmission line.

[0014] The second parasitic patch and the third parasitic patch are circular.

[0015] The dielectric substrate is a cubic insulating dielectric layer, and the coplanar waveguide structure, microstrip transmission line and first parasitic patch are all rectangular.

[0016] The coplanar waveguide structure, microstrip transmission line and ground plane are made of metal.

[0017] It also includes a wave port excitation, and the wave port excitation is arranged between the microstrip transmission line and the ground plate.

[0018] The dielectric substrate is made of epoxy resin with a relative dielectric constant of 4.4.

[0019] Compared with the prior art, the present invention adds parasitic patches at appropriate positions, which increases the bandwidth and has significant gain, achieving a trade-off effect. The multi-frequency broadband microstrip antenna of the present invention adopts microstrip transmission lines, coplanar waveguides, ground planes, front parasitic patches, back parasitic patches and wave port excitation structures to achieve broadband multi-frequency effects. The designed frequency band can cover the wireless local area network (WLAN) and the World Wide Web of Microwave Access (WiMAX) frequency bands, and can work in multiple frequency bands at the same time. Moreover, the multi-frequency broadband microstrip antenna also has the advantages of simple structure, reasonable design and easy manufacturing. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a structural schematic diagram of the novel multi-frequency broadband microstrip antenna of the present invention;

[0021] Figure 2 It is a front schematic diagram of the novel multi-frequency broadband microstrip antenna of the present invention;

[0022] Figure 3 It is a schematic diagram of the back side of the novel multi-frequency broadband microstrip antenna of the present invention;

[0023] In the figure: 1, dielectric substrate; 201, first coplanar waveguide ground plane; 202, second coplanar waveguide ground plane; 3, microstrip transmission line; 4, first parasitic patch; 501, second parasitic patch; 502, third parasitic patch; 6, ground plane; 7, wave port excitation;

[0024] Figure 4 This is the return loss simulation diagram of the antenna;

[0025] Figure 5 This is the voltage standing wave ratio simulation diagram of the antenna;

[0026] Figure 6 The E-plane and H-plane radiation patterns of the antenna at 3.2GHz;

[0027] Figure 7 is the 3D radiation pattern of the antenna at 3.2GHz;

[0028] Figure 8 The E-plane and H-plane radiation patterns of the antenna at 3.5GHz;

[0029] Fig. 9 is the 3D radiation pattern of the antenna at 3.5GHz;

[0030] Fig.10 The E-plane and H-plane radiation patterns of the antenna at 4.8GHz;

[0031] Fig.11 is the 3D radiation pattern of the antenna at 4.8GHz;

[0032] Fig.12The E-plane and H-plane radiation patterns of the antenna at 5.2GHz;

[0033] Fig.13 This is the 3D radiation pattern of the antenna at 5.2 GHz. DETAILED DESCRIPTION

[0034] The present invention is further described below in conjunction with specific embodiments.

[0035] A new type of multi-frequency broadband microstrip antenna, such as Figures 1 to 3 As shown, it includes a dielectric substrate 1, a coplanar waveguide structure, a microstrip transmission line 3, a first parasitic patch 4, a second parasitic patch 501, a third parasitic patch 502, a ground plate 6 and a wave port excitation 7.

[0036] The dielectric substrate 1 is a cubic insulating dielectric layer.

[0037] The microstrip transmission line 3 is rectangular and is located at the center of the upper surface of the dielectric substrate 1 .

[0038] The coplanar waveguide structure is placed on the upper surface of the dielectric substrate 1. The coplanar waveguide structure includes a rectangular first coplanar waveguide ground plane 201 and a second coplanar waveguide ground plane 202 of the same size. The first coplanar waveguide ground plane 201 and the second coplanar waveguide ground plane 202 are symmetrically placed on both sides of the microstrip transmission line 3, respectively. There are gaps between the first coplanar waveguide ground plane 201 and the second coplanar waveguide ground plane 202 and the microstrip transmission line 3. The length of the coplanar waveguide structure is shorter than the microstrip transmission line 3.

[0039] The ground plate 6 is semicircular and is located on the lower surface of the dielectric substrate 1 , with the center of the circle being located just below one end of the microstrip transmission line 3 .

[0040] The first parasitic patch 4 is rectangular and smaller than the second coplanar waveguide ground plane 202 . It is also located on the upper surface of the dielectric substrate 1 and is arranged at an end of the second coplanar waveguide ground plane 202 away from the ground plane 6 and close to the microstrip transmission line 3 .

[0041] A second parasitic patch 501 and a third parasitic patch 502 of circular shape and identical size are also provided on the lower surface of the dielectric substrate 1 . The second parasitic patch 501 and the third parasitic patch 502 are symmetrically placed on both sides directly below the microstrip transmission line 3 .

[0042] The coplanar waveguide structure, the microstrip transmission line 3 and the ground plate 6 are all made of metal, generally copper.

[0043] The wave port excitation 7 is arranged between the microstrip transmission line 3 and the ground plane 6. The microstrip transmission line 3, the coplanar waveguide structure 2, the microstrip transmission line 3 and the ground plane 6 are used for feeding, and the wave port 7 is used for excitation to obtain good performance matching and realize multi-frequency broadband effect.

[0044] Example

[0045] A novel multi-frequency broadband microstrip antenna uses a PCB board as a dielectric substrate and then welds an SMA connector. The dielectric substrate 1 is 35mm long, 22mm wide and 1mm high; the first coplanar waveguide ground plane 201 and the second coplanar waveguide ground plane 202 are 17mm long and 9.8mm wide, and the gaps between them and the microstrip transmission line 3 are both 0.2mm; the first parasitic patch 4 is 2.5mm long and 2.5mm wide, and is 7.1mm away from the right edge of the dielectric substrate 1; the microstrip transmission line 3 is 33mm long and 2mm wide; the radius of the two circular parasitic patches 501 and 502 on the back is 2.5mm, and the radius of the semicircular ground plane 6 is 6mm;

[0046] The working principle is as follows: the main part of the multi-frequency broadband microstrip is an insulating dielectric layer that is much smaller than the working wavelength. One side is a coplanar waveguide structure and a microstrip transmission line, and the other side is a semicircular ground plane. The microstrip line and the coplanar waveguide are fed together, the coplanar waveguide and the semicircular surface are grounded, and parasitic patches and multiple ground planes are added to the coplanar waveguide structure to achieve a multi-frequency effect. A parasitic patch is added to the back to reduce its return loss to achieve a broadband effect. When only the main mode excitation is considered, lumped port excitation is used, and the input impedance matching is set to 50 ohms to obtain a good performance match. In this antenna, the effect obtained is very reasonable and practical, with excellent return loss and directivity. 11 <-10dB, each frequency point can achieve multi-frequency effect, that is, multi-frequency broadband effect can be achieved at the same time. 3.5GHz and 5.2GHz generally cover WLAN and WiMAX systems.

[0047] By performing HFSS simulation on the designed structure, the software is used to test the various performance indicators of the antenna, and the antenna return loss, radiation pattern and 3D gain diagram ( Figures 4 to 12 ).

[0048] like Figure 4 As shown in the figure, the return loss and voltage standing wave ratio of the antenna are one-to-one corresponding. In general, the voltage standing wave ratio is 2, and the corresponding return loss is -10dB. If the voltage standing wave ratio is less than 2, the return loss will be lower than -10dB. The antenna can be used if the return loss effect is lower than -10dB. It can be seen that the antenna has a long available bandwidth and has the characteristics of ultra-wideband. Figure 5 It is the voltage standing wave ratio diagram. The part below 2 can be used. Figure 4 Correspondingly, it is proved that the antenna is practical.

[0049] The multi-frequency broadband microstrip antenna of this embodiment uses a microstrip transmission line and a coplanar waveguide for feeding. Parasitic patches are added to the coplanar waveguide structure and at appropriate positions on the back of the insulating dielectric layer to generate multiple resonance points, thereby achieving a multi-frequency effect. 11 =-10dB, f L =2.9561GHz, f H =5.4504GHz, at f L and f H Room, S 11 <-10dB, the absolute bandwidth of the antenna is B = f H -f L =2.4943GHz, relative bandwidth Br=59%, the bandwidth is significantly increased compared with before, and the antenna effect can be achieved within the broadband. At the same time, this frequency band covers the frequency band structure of WLAN, WiMAX, etc.

[0050] like Figure 6 and 7 As shown, the return loss frequency is 3.2GHz, and when the main radiation is at 0° or 360°, the gain is maximum, which is 2.139dB; Figure 8 and 9 As shown, the return loss frequency is 3.5GHz. When the main radiation is at 0° or 360°, the gain is maximum, which is 2.37dB, and the radiation effect is good. Fig.10 and 11 As shown in the figure, when the return loss frequency is 4.8GHz, the maximum gain is 3.436dB; Fig.12 and 13 As shown in the figure, when the return loss frequency is 5.2GHz, the maximum gain is 4.078dB. From the 3D gain pattern at these frequencies, it can be seen that the radiation intensity is significantly enhanced, the radiation range can achieve omnidirectional radiation and the radiation range is large, and the main radiation area is located at the upper and lower ends, so the antenna design is very reasonable, and in S 11 <-10dB, each frequency point can achieve multi-frequency effect, with good working performance, excellent return loss and directivity, and is very practical.

Claims

1. A novel multi-frequency broadband microstrip antenna, comprising a dielectric substrate (1), characterized in that: Also includes a coplanar waveguide structure, a microstrip transmission line (3) and a ground plate (6); The coplanar waveguide structure and the microstrip transmission line (3) are placed on the upper surface of the dielectric substrate (1); the length of the coplanar waveguide structure is shorter than that of the microstrip transmission line (3); the coplanar waveguide structure comprises a first coplanar waveguide ground plane (201) and a second coplanar waveguide ground plane (202) of the same size; the first coplanar waveguide ground plane (201) and the second coplanar waveguide ground plane (202) are symmetrically placed on both sides of the microstrip transmission line (3); and gaps are left between the first coplanar waveguide ground plane (201) and the second coplanar waveguide ground plane (202) and the microstrip transmission line (3); The ground plate (6) is placed on the lower surface of the dielectric substrate (1), and the ground plate (6) is located directly below one end of the microstrip transmission line (3); A first parasitic patch (4) is also provided on the upper surface of the dielectric substrate (1), and the first parasitic patch (4) is arranged at an end of the second coplanar waveguide ground plane (202) away from the ground plane (6) and close to the microstrip transmission line (3); A second parasitic patch (501) and a third parasitic patch (502) of the same size are also provided on the lower surface of the dielectric substrate (1); the second parasitic patch (501) and the third parasitic patch (502) are symmetrically placed on both sides directly below the microstrip transmission line (3); The ground plate (6) is semicircular, with the center of the circle located directly below one end of the microstrip transmission line (3); the first parasitic patch (4) is rectangular; and the second parasitic patch (501) and the third parasitic patch (502) are circular.

2. The novel multi-frequency broadband microstrip antenna according to claim 1 is characterized in that: The dielectric substrate (1) is a cubic insulating dielectric layer, and the coplanar waveguide structure, the microstrip transmission line (3) and the first parasitic patch (4) are all rectangular.

3. The novel multi-frequency broadband microstrip antenna according to claim 1 is characterized in that: The coplanar waveguide structure, the microstrip transmission line (3) and the ground plate (6) are made of metal.

4. The novel multi-frequency broadband microstrip antenna according to claim 1, characterized in that: It also includes a wave port excitation (7), wherein the wave port excitation (7) is arranged between the microstrip transmission line (3) and the ground plate (6).

5. The novel multi-frequency broadband microstrip antenna according to claim 1 is characterized in that: The material of the dielectric substrate (1) is epoxy resin with a relative dielectric constant of 4.4.

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