A low-profile broadband non-reflective patch antenna

Abstract

The present invention discloses a low-profile broadband non-reflection patch antenna, which combines broadband edge radiation supported by coupling an inverted U-shaped metal patch and a stepped metal strip with a broadband band-stop filter supported by an embedded interdigital structure, and a second vertical microstrip line and a first horizontal microstrip line supporting matching adjustment through a grounding resistor to realize a low-profile broadband non-reflection patch antenna with broadband radiation working bandwidth and broadband non-reflection bandwidth, a simple structure, and consideration of ground integrity and small size.

Description

Technical Field

[0001] The invention relates to a microwave communication device, in particular to a non-reflective patch antenna. Background Art

[0002] A non-reflective patch antenna is a patch antenna that can be matched both inside and outside the working frequency band. It can suppress the reflection of out-of-band signals without adding isolators or circulators, and prevent out-of-band reflected signals from affecting or damaging active devices. Therefore, it can simplify the system to a certain extent, reduce the number of components in the system, and reduce losses and costs. At the same time, as the speed and capacity of wireless systems increase, the bandwidth of non-reflective patch antennas also needs to be improved. However, the bandwidth of patch antennas is usually linked to the profile height and complexity of the antenna, and non-reflective patch antennas face the same problem. Therefore, achieving broadband patch antenna radiation function and broadband non-reflection function under low profile conditions will make this type of non-reflective patch antenna more advantageous.

[0003] There are three main design methods for existing broadband non-reflective patch antennas. The first is to use a double-branch resonator and a pair of slot-loaded patches, combined with a band-stop filter composed of a U-shaped defect microstrip and a U-shaped defect ground, to realize a non-reflective patch antenna, but there are problems with narrow radiation bandwidth and non-reflective bandwidth, and the structure of multiple defect grounds increases the complexity of the structure. The second is to use a U-shaped slot-loaded patch and a pair of quarter-wavelength microstrip coupling lines below it to realize a dual-band non-reflective patch antenna in the form of a dual antenna, but the radiation bandwidth is still narrow, and the size of the dual antenna structure is large and the structure is complex. The third is to use stacked patches and a band-stop filter realized by an ear-shaped defect ground to realize a broadband non-reflective patch antenna, but the overall non-reflective bandwidth still needs to be improved, and there are problems such as high profile, incomplete ground, and complex structure. Therefore, it is necessary to propose a broadband non-reflective patch antenna under low-profile conditions, which can achieve a wide radiation band, a wide out-of-band non-reflection band and a low profile while taking into account the integrity, structural complexity and size of the ground. Summary of the invention

[0004] Purpose of the invention: In view of the above-mentioned prior art, a low-profile broadband non-reflection patch antenna is proposed to achieve a wide radiation band, a wide out-of-band non-reflection band and a low profile.

[0005] Technical solution: A low-profile broadband non-reflective patch antenna, comprising a top metal structure, an upper dielectric substrate, an intermediate metal ground, a lower dielectric substrate, and a bottom structure which are stacked in sequence;

[0006] The top metal structure includes an inverted U-shaped metal patch and a stepped metal strip; the stepped metal strip is vertically located in the center of the notch of the inverted U-shaped metal patch, and its top narrow side is adjacent to the middle narrow line segment of the inverted U-shaped metal patch, with a coupling gap between the two;

[0007] The bottom layer structure includes a first vertical metal strip, a second vertical metal strip, a first horizontal metal strip, a third vertical metal strip, a resistor and a metal disk; wherein the third vertical metal strip has two interdigitated structures embedded in the length direction; the first vertical metal strip is arranged opposite to the step-type metal strip, and the second vertical metal strip is connected in series to the top of the first vertical metal strip; the right end of the first horizontal metal strip is connected in parallel to the connection between the first vertical metal strip and the second vertical metal strip; the left side of the first horizontal metal strip is connected in series with the third vertical metal strip, the resistor and the metal disk in sequence along the vertical direction; the metal disk is connected to the middle layer metal ground through a metallized blind hole; the top of the second vertical metal strip is connected to the top of the step-type metal strip through a metallized via.

[0008] Furthermore, the horizontal length of the inverted U-shaped metal patch is 0.50 l 0-0.53 l 0, the upper and lower lengths are 0.21 l 0-0.23 l 0, the horizontal length of the inner notch is 0.20 l 0-0.22 l 0; the stepped metal strip is a metal strip with a narrowed top and a total length of 0.23 l 0-0.24 l 0, the width of the bottom wide edge is 0.05 l 0-0.06 l 0.

[0009] Furthermore, two interdigital structures are embedded in the third vertical metal strip to form a broadband band-stop filter; the length of the interdigital structure is 0.06 l 0-0.08 l 0, the overall width accounts for 88%-90% of the third vertical metal strip line width, and the spacing between the two interdigital structures is 0.03 l 0-0.05 l 0.

[0010] Furthermore, the length of the second vertical metal strip is 0.11 l 0-0.12 l 0, the length of the first horizontal metal strip is 0.25 l 0-0.27 l 0.

[0011] Furthermore, the equivalent self-inductance and self-capacitance of the interdigital structure form a band-stop type self-resonance, and the coupling between the band-stop type self-resonances is adjusted by the distance between the two interdigital structures, thereby regulating the out-of-band suppression level of the band-stop response.

[0012] Furthermore, the resonant frequency of the band-stop filter is regulated by the length of the interdigital structure.

[0013] Beneficial effects: Existing non-reflective patch antennas generally cannot achieve a wide radiation band and a wide non-reflection band at the same time under low-profile conditions. At the same time, the antenna complexity is high, and some designs also have problems such as incomplete ground or large size. The key point of the present invention is that the broadband edge radiation supported by the coupling of the inverted U-shaped metal patch and the stepped metal strip and the broadband band-stop filter supported by the embedded interdigital structure are combined with the second vertical microstrip line and the first horizontal microstrip line that support matching adjustment through the grounding resistor to realize a low-profile broadband non-reflective patch antenna with broadband radiation working bandwidth and broadband non-reflection bandwidth, simple structure, and taking into account the integrity and small size of the ground.

[0014] Specifically, when working, the left and right sides of the inverted U-shaped metal patch are vertical currents in the same direction, and then extend to the middle horizontal part to form a reverse current in the horizontal part, and the whole is a full-wave current; there is a half-wave vertical current in the step-type metal strip; the two are coupled through the gap in the vertical direction to realize two resonance points polarized in the vertical direction, and obtain wide-band side-radiation.

[0015] The third vertical metal strip embedded with two interdigitated structures constitutes a broadband band-stop filter. The equivalent self-inductance and self-capacitance of the interdigitated structure form a band-stop self-resonance. The distance between the two is conducive to regulating the out-of-band suppression level. The interdigitated length can regulate the resonant frequency of the band-stop filter. Increasing the proportion of the overall width of the interdigitated structure to the line width of the third vertical metal strip is conducive to reducing the length of the band-stop filter and achieving a wider stopband bandwidth.

[0016] The second vertical microstrip line is connected to the first horizontal microstrip line, and the other ends of the two are respectively connected to a band-stop filter composed of a stepped metal strip and an interdigitated structure. The second vertical microstrip line and the first horizontal metal strip can adjust the impedance matching between the top-layer broadband radiator and the broadband band-stop filter of the bottom-layer termination resistor, thereby achieving normal broadband matching within the radiation band and a wide range of out-of-band reflection-free coverage. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic cross-sectional structure diagram of a low-profile broadband non-reflective patch antenna of the present invention;

[0018] Figure 2It is a schematic diagram of the top metal structure of the low-profile broadband non-reflection patch antenna of the present invention;

[0019] Figure 3 It is a schematic diagram of the metal ground structure of the middle layer of the low-profile broadband non-reflection patch antenna of the present invention;

[0020] Figure 4 It is a schematic diagram of the underlying structure of the low-profile broadband non-reflective patch antenna of the present invention;

[0021] Figure 5 The S parameters and gain simulation results of the embodiment of the present invention and the traditional single-layer patch antenna;

[0022] Figure 6 The simulated directional pattern of the embodiment of the present invention within the working frequency band, where (a) is 4.84 GHz E Simulated radiation pattern, (b) is at 4.84 GHz H Simulated radiation pattern, (c) is 5.14 GHz E Simulated radiation pattern, (d) is 5.14GHz H Surface simulation pattern. DETAILED DESCRIPTION

[0023] The present invention will be further explained below in conjunction with the accompanying drawings.

[0024] like Figure 1 As shown, a low-profile broadband non-reflective patch antenna is mainly composed of a top metal structure 1, an upper dielectric substrate 2, a middle metal ground 3, a lower dielectric substrate 4, a bottom structure 5, a metalized blind hole 6 and a metalized via 7.

[0025] The top metal structure 1 is located on the upper surface of the upper dielectric substrate 2. Figure 2 As shown, it includes an inverted U-shaped metal patch 101 and a stepped metal strip 102. The inverted U-shaped metal patch 101 is located in the center of the substrate, with its opening facing downward, and its horizontal (x-axis direction in the figure) length of the outline is 0.50 l 0-0.53 l 0, the upper and lower lengths of the contour (y-axis direction in the figure) are between 0.21 l 0-0.23 l 0, the horizontal length of the inner notch is 0.20 l 0-0.22 l 0, l0 is the free space wavelength corresponding to the center frequency. The stepped metal strip 102 is a metal strip with a narrowed top. The stepped metal strip 102 is vertically located in the center of the notch of the inverted U-shaped metal patch 101. Its top narrow side is adjacent to the middle narrow line segment of the inverted U-shaped metal patch, and a coupling gap is left between the two. The total length of the stepped metal strip 102 (in the y-axis direction in the figure) is 0.23 l 0-0.24 l 0, the width of the bottom wide edge is 0.05 l 0-0.06 l 0.

[0026] The middle metal ground 3 is located between the upper dielectric substrate 2 and the lower dielectric substrate 4. Figure 3 As shown, there is a circular groove 301 on the middle layer metal ground 3 for the metallized via 7 to pass through.

[0027] The bottom structure 5 is located on the lower surface of the lower dielectric substrate 4. Figure 4 As shown, the bottom structure includes a first vertical metal strip 501, a second vertical metal strip 502, a first horizontal metal strip 503, a third vertical metal strip 504, a resistor 506 and a metal plate 507. The third vertical metal strip 504 has two interdigital structures 505 embedded in the length direction. The first vertical metal strip 501 is arranged opposite to the stepped metal strip 102, and its bottom is flush with the bottom edge of the antenna. The second vertical metal strip 502 is connected in series to the top of the first vertical metal strip 501, and its length is 0.11 l 0-0.12 l 0. The right end of the first horizontal metal strip 503 is connected in parallel to the connection between the first vertical metal strip 501 and the second vertical metal strip 502. The left side of the first horizontal metal strip 503 is connected in series with the third vertical metal strip 504, the resistor 506 and the metal plate 507 in the vertical direction. In this embodiment, the length of the first horizontal metal strip 503 is 0.25 l 0-0.27 l 0; both interdigital structures 505 have five fingers, and the length of the interdigital structures 505 is between 0.06 l 0-0.08 l 0, the overall width of the interdigital structure 505 accounts for 88%-90% of the line width of the third vertical metal strip 504, and the spacing between the two interdigital structures 505 is 0.03 l 0-0.05 l 0. The metal plate 507 is connected to the middle layer metal ground 3 through the metalized blind hole 6. The top of the second vertical metal strip 502 is connected to the top of the step metal strip 102 through the metalized via 7. The distance between the metalized via 7 and the top edge of the step metal strip 102 is 0.09 l0-0.10 l 0.

[0028] The inverted U-shaped metal patch 101, the stepped metal strip 102, the upper dielectric substrate 2 and the middle metal ground 3 constitute the radiator of the antenna. The first vertical metal strip 501, the second vertical metal strip 502, the first horizontal metal strip 503, and the third vertical metal strip 504 respectively form the first vertical microstrip line, the second vertical microstrip line, the first horizontal microstrip line and the third vertical microstrip line with the lower dielectric substrate 4 and the middle metal ground 3, wherein the first vertical microstrip line is the antenna feed line.

[0029] For the proposed low-profile broadband non-reflective patch antenna, one signal is fed into the antenna's radiator through the first and second vertical microstrip lines, and the other signal flows to the resistor through the first horizontal microstrip line, the interdigital structure, and the third vertical metal strip, forming broadband non-reflective edge radiation as a whole. In this process, the inverted U-shaped metal patch and the stepped metal strip are coupled through the gap in the vertical direction between the two. The top narrow side width of the stepped metal strip can adjust the coupling amount between the two. Combined with the metallized via position, the second vertical microstrip line, and the first horizontal microstrip line, two reflection zero points within the antenna radiation band can be achieved to form broadband radiation. At the first reflection zero point, the radiator current is mainly distributed on the inverted U-shaped metal patch, with the left and right sides being the same-direction vertical current, and then extending to the middle horizontal part to form the reverse current of the horizontal part, which is a full-wave current as a whole, thus forming vertically polarized edge radiation. At the second reflection zero point, the current is mainly concentrated on the narrow line segment between the stepped metal strip and the inverted U-shaped metal patch. The stepped metal strip is a half-wave vertical current, and the narrow line segment in the middle of the inverted U-shaped metal patch is a shorter reverse current, thus also forming vertically polarized edge radiation.

[0030] The equivalent self-inductance and self-capacitance of the interdigital structure of the third vertical metal strip form a band-stop self-resonance. The distance between the two interdigital structures can control the coupling between the band-stop self-resonances, thereby regulating the out-of-band suppression level of the band-stop response. By controlling the length of the interdigital structure, the center frequency of the band-stop filter is kept consistent with the antenna radiator, and the reverse current presented by adjacent interdigital fingers can suppress back radiation leakage. Increasing the proportion of the overall width of the interdigital structure to the line width of the third vertical metal strip is conducive to reducing the length of the band-stop filter and achieving a wider stopband bandwidth.

[0031] The second vertical microstrip line and the first horizontal microstrip line are used to reduce the high reactance characteristics of the band-stop filter of the termination resistor within the working frequency band and the high resistance characteristics outside the working frequency band. They can adjust the impedance matching between the top-layer broadband radiator and the broadband band-stop filter of the bottom-layer termination resistor, and achieve normal broadband matching within the radiation band and a wide range of out-of-band reflection-free coverage.

[0032] Compared with the prior art, the non-reflective patch antenna of the present invention can simultaneously improve the working bandwidth and non-reflective bandwidth under low profile conditions, reduce the structural complexity, and take into account the integrity of the ground and the small size of the antenna. The dielectric substrate used in this embodiment is RO4003C, and the overall size is 0.54 l 0×0.27 l 0, the section height is only 0.039 l 0. Figure 5 The simulation results of the S parameters and gain of this embodiment and the traditional single-layer patch antenna are compared. Figure 5 It can be seen that the -10dB impedance matching frequency band of this embodiment covers 3.87 GHz to 6.93 GHz, with a relative bandwidth of 61.2%, and the effective working frequency band of antenna radiation covers 4.79 GHz to 5.21 GHz, with a relative bandwidth of 8.4% (center frequency is 5GHz), while the -10dB impedance matching frequency band of the traditional single-layer patch antenna is the same as the effective radiation working frequency band, covering 4.94 GHz to 5.09 GHz, with a relative bandwidth of only 3%. Figure 5 It can also be seen that the maximum gain of this embodiment is almost equal to the maximum gain value of the traditional single-layer patch antenna, which is about 6.6 dBi, and the out-of-band suppression of this embodiment is significantly higher than that of the traditional patch antenna. Figure 6 The present embodiment is shown to have good performance at two resonant frequencies. E Face to face H From the normalized simulation direction diagram, we can see that E Face to face H The radiation patterns of the two planes are symmetrical, and the cross-polarization levels are greater than 15dB.

[0033] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A low-profile broadband non-reflective patch antenna, characterized in that: It comprises a top metal structure (1), an upper dielectric substrate (2), an intermediate metal ground (3), a lower dielectric substrate (4), and a bottom structure (5) which are stacked in sequence; The top metal structure (1) comprises an inverted U-shaped metal patch (101) and a stepped metal strip (102); the stepped metal strip (102) is a metal strip narrowed at the top; the inverted U-shaped metal patch (101) is composed of a middle narrow line segment and two vertical wide line segments; the stepped metal strip (102) is vertically located in the center of the notch of the inverted U-shaped metal patch (101), and its top narrow side is adjacent to the middle narrow line segment of the inverted U-shaped metal patch, with a coupling gap left between the two; The bottom layer structure (5) comprises a first vertical metal strip (501), a second vertical metal strip (502), a first horizontal metal strip (503), a third vertical metal strip (504), a resistor (506) and a metal plate (507); wherein the third vertical metal strip (504) has two interdigitated structures (505) embedded in the length direction; the first vertical metal strip (501) is arranged along the length direction of the stepped metal strip (102); the second vertical metal strip (502) is connected in series to the top of the first vertical metal strip (501); The first horizontal metal strip (503) is connected in parallel to the connection between the first vertical metal strip (501) and the second vertical metal strip (502) at its right end; the third vertical metal strip (504), the resistor (506) and the metal plate (507) are connected in series in sequence along the vertical direction on the left side of the first horizontal metal strip (503); the metal plate (507) is connected to the middle layer metal ground (3) through a metallized blind hole (6); and the top of the second vertical metal strip (502) is connected to the stepped metal strip (102) through a metallized via (7).

2. The low-profile broadband non-reflective patch antenna according to claim 1, characterized in that: The horizontal length of the inverted U-shaped metal patch (101) is 0.50 λ 0-0.53 λ 0, the upper and lower lengths are 0.21 λ 0-0.23 λ 0, the horizontal length of the inner notch is 0.20 λ 0-0.22 λ 0; the total length of the stepped metal strip (102) is between 0.23 λ 0-0.24 λ 0, the width of the bottom wide edge is 0.05 λ 0-0.06 λ 0, λ 0 is the free space wavelength corresponding to the center frequency.

3. The low-profile broadband non-reflective patch antenna according to claim 2, characterized in that: Two interdigital structures (505) are embedded in the third vertical metal strip (504) to form a broadband band-stop filter; the length of the interdigital structure (505) is 0.06 λ 0-0.08 λ 0, the overall width accounts for 88%-90% of the line width of the third vertical metal strip (504), and the spacing between the two interdigital structures (505) is 0.03 λ 0-0.05 λ 0.

4. The low-profile broadband non-reflective patch antenna according to claim 2 or 3, characterized in that: The length of the second vertical metal strip (502) is 0.11 λ 0-0.12 λ 0, the length of the first horizontal metal strip (503) is between 0.25 λ 0-0.27 λ 0.

5. The low-profile broadband non-reflective patch antenna according to claim 3, characterized in that: The equivalent self-inductance and self-capacitance of the interdigital structure (505) form a band-stop type self-resonance, and the coupling between the band-stop type self-resonances is adjusted by the distance between the two interdigital structures (505), thereby regulating the out-of-band suppression level of the band-stop response.

6. The low-profile broadband non-reflective patch antenna according to claim 3, characterized in that: The resonant frequency of the band-stop filter is regulated by the length of the interdigital structure (505).

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